tag:theconversation.com,2011:/us/topics/breast-screening-3765/articlesBreast screening – The Conversation2019-09-18T20:37:08Ztag:theconversation.com,2011:article/1221262019-09-18T20:37:08Z2019-09-18T20:37:08ZFor routine breast screening, you may not need a 3D mammogram<figure><img src="https://images.theconversation.com/files/292746/original/file-20190917-19083-1kzbsly.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4992%2C3318&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">3D mammograms may be useful in investigating abnormalities, but as a means of routine screening, they may do more harm than good.</span> <span class="attribution"><span class="source">From shutterstock.com</span></span></figcaption></figure><p>Victorian Minister for Health Jenny Mikakos recently announced <a href="https://www.jennymikakos.com.au/media-releases/cutting-edge-3d-breast-cancer-imaging-to-save-lives/">six new 3D breast screening machines</a> would be rolled out across the state. </p>
<p>These will be used to assess women recalled for further investigation when a standard 2D screening mammogram picks up something that wasn’t anticipated. </p>
<p>Offering this sophisticated technology within the public system is designed to help women with breast cancer receive an accurate diagnosis in a timely manner, in turn ensuring they can start appropriate treatment as early as possible. </p>
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<a href="https://theconversation.com/what-causes-breast-cancer-in-women-what-we-know-dont-know-and-suspect-86314">What causes breast cancer in women? What we know, don't know and suspect</a>
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<p>But there’s a distinction to be made here. While this funding will provide 3D mammography machines to be used for further assessment when there may be a problem, many 3D mammography machines are already operating throughout the private system, offered to women as a means for routine screening. </p>
<p>Newer medical technology is often assumed to be better than traditional technology. But when we’re talking about mammography for routine breast screening, this may not be the case.</p>
<p>While <a href="https://jamanetwork.com/journals/jamaoncology/article-abstract/2726028">evidence shows</a> 3D mammograms detect more cases of breast cancer than the 2D version, many of the additional cancers detected may not go on to cause harm. In these cases, their detection will only lead to anxiety and unnecessary treatment. </p>
<h2>What is a mammogram?</h2>
<p>A mammogram is an x-ray of the breasts that can be used to investigate breast symptoms such as lumps and pain. It can also be used for screening, to pick up early breast cancer in healthy women who have no symptoms.</p>
<p>In Australia, the <a href="http://www.cancerscreening.gov.au/internet/screening/publishing.nsf/Content/breast-screening-1">BreastScreen program</a> invites women aged 50 to 74 for a free screening mammogram every two years. All women over 40 are welcome to attend if they choose to.</p>
<p>The BreastScreen program offers conventional 2D digital mammograms. During this standard mammogram, compression is applied to the breast, and two images are taken of each breast using a small dose of radiation. </p>
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Read more:
<a href="https://theconversation.com/women-should-be-told-about-their-breast-density-when-they-have-a-mammogram-66125">Women should be told about their breast density when they have a mammogram</a>
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<h2>What does a 3D mammogram do differently?</h2>
<p>3D mammography, also called <a href="https://www.insideradiology.com.au/breast-tomosynthesis/">breast tomosynthesis</a>, has been introduced over the last decade. </p>
<p>It’s not currently used for screening as part of the BreastScreen program, but it is available in many private radiology practices around the country.</p>
<p>A 3D mammogram applies the same compression to the breast as a 2D test, but takes multiple images, like thin “slices”. </p>
<p>The radiologist can scroll through the collection of images on a computer screen to get a 3D picture of the breast, which can be examined layer by layer, one millimetre at a time. This aims to see through layers of normal breast tissue to find hidden cancer.</p>
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<figcaption><span class="caption">Source: Breast Imaging Victoria.</span></figcaption>
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<p><a href="https://jamanetwork.com/journals/jamaoncology/article-abstract/2726028">Research</a> has shown 3D mammograms are able to pick up some cancers not seen on conventional 2D mammograms. The cancer detection rate of 3D mammography was around 1.4 times higher than for 2D mammography. </p>
<p>The additional cancers detected by 3D mammograms were small and had not spread to the lymph glands; these are early cancers expected to have better survival rates.</p>
<p>Cancer can be difficult to see in lumpy or dense glandular breast tissue, which is typically seen in women before menopause. 3D mammography appears to be <a href="https://academic.oup.com/jnci/article/110/9/942/5068658">particularly good</a> at detecting cancer in women with dense breast tissue, which may partially account for the increase in detection. </p>
<h2>The possibility of overdiagnosis and overtreatment</h2>
<p>Some cancers are indolent or slow growing and will never cause clinical symptoms. These cancers can be difficult to distinguish from aggressive cancers detected early. So when they’re found by a screening mammogram, they may be treated with surgery and radiotherapy, causing harm without improving survival.</p>
<p>When we’re talking about breast screening, we’ll often mention the recall rate. That’s the number of women asked to return for further testing, and possibly treatment, when an initial screening shows up something abnormal. </p>
<p>The recall rate is important because, we know for 2D mammography, <a href="https://www.aihw.gov.au/getmedia/c28cd408-de89-454f-9dd0-ee99e9163567/aihw-can-116.pdf.aspx?inline=true">around 80-90% of women recalled</a> for assessment do not have cancer. </p>
<p>In these cases, being recalled can lead to anxiety, risks and pain associated with biopsy and surgery, and costs for unnecessary procedures.</p>
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<span class="caption">While a 3D mammogram might pick up more cancers, it could necessitate treatment for cancers not destined to cause harm.</span>
<span class="attribution"><span class="source">From shutterstock.com</span></span>
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<p>Earlier <a href="https://jamanetwork.com/journals/jamaoncology/article-abstract/2726028">research</a> found the recall rate was lower for 3D mammography than 2D mammography, so there were fewer false positive studies or false alarms that added extra tests, biopsies and anxiety. </p>
<p>But new <a href="https://onlinelibrary.wiley.com/doi/abs/10.5694/mja2.50320">Australian research</a>, published in the Medical Journal of Australia, has drawn this into question. This study included more than 10,000 women attending a BreastScreen centre in Victoria for routine screening. Some were invited to have a 3D mammogram, while others had a conventional 2D mammogram.</p>
<p>Again, the cancer detection rate was around 1.5 times higher for 3D mammography. However, the recall rate was actually higher for 3D mammography compared to 2D – so more women were asked to return for further work-up (mammogram, ultrasound and/or a biopsy).</p>
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Read more:
<a href="https://theconversation.com/three-questions-to-ask-about-calls-to-widen-breast-cancer-screening-82894">Three questions to ask about calls to widen breast cancer screening</a>
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<h2>Should I have a 3D mammogram?</h2>
<p>Public health experts are currently debating the issue of <a href="https://www.nejm.org/doi/10.1056/NEJMoa1600249?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%3dwww.ncbi.nlm.nih.gov">overdiagnosis in breast screening</a>. The extent of overdiagnosis in screening is not agreed upon, but it is accepted that it exists to some extent. </p>
<p>In the 3D mammography studies, including the latest Australian study, a higher proportion of cancers in the 3D groups were very small invasive or “in situ” malignancies less likely to cause harm than more aggressive cancers. This means many of the additional cancers detected by 3D mammograms could be “over-diagnosed” cancers that cause women to undergo gruelling cancer treatments without real benefit.</p>
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Read more:
<a href="https://theconversation.com/treating-stage-0-breast-cancer-doesnt-always-save-womens-lives-so-should-we-screen-for-it-46624">Treating 'stage 0' breast cancer doesn't always save women's lives so should we screen for it?</a>
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<p>It’s unlikely BreastScreen will introduce routine 3D mammography screening in the short term based on the current evidence.</p>
<p>But should you have a 3D mammogram through a private radiology practice? Perhaps, if you have dense breast tissue or you are starting screening in your 30s or 40s due to a family history of breast cancer. </p>
<p>For older women, there may not be additional benefits of 3D mammography over 2D. All women should consider the balance of potential benefits (early detection) and potential harms (overdiagnosis, overtreatment and anxiety) before deciding on a 3D versus a 2D screening mammogram.</p><img src="https://counter.theconversation.com/content/122126/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Meagan Brennan does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>3D mammography is becoming more widely available, but is it superior to the traditional 2D technology for breast cancer detection? The answer isn’t clear-cut.Meagan Brennan, Clinical A/Prof Breast Physician, Westmead Breast Cancer Institute, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/442572015-07-08T15:02:53Z2015-07-08T15:02:53ZCelebrity campaigns are a distraction from the real risks of cancer screening<figure><img src="https://images.theconversation.com/files/87596/original/image-20150707-1297-36xxpi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Unnecessary worry?</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>You may have read stories about people who believe their <a href="http://www.telegraph.co.uk/finance/personalfinance/insurance/privatemedical/8813595/When-it-pays-to-go-private-500-test-saved-my-life.html">lives were saved</a> because of a routine screening for a disease such as cancer. Or you may have heard of people who feel they were let down because they <a href="http://www.mirror.co.uk/news/uk-news/sophie-jones-petition-cervical-screening-3253376">didn’t receive such screening</a>. While they make compelling media stories, this kind of media coverage of screening is often incomplete and misleading.</p>
<p>It has helped to create unrealistic expectations of what screening programmes are and what they can deliver. On the one hand, there is a <a href="http://jnci.oxfordjournals.org/content/101/17/1216">mistaken belief</a> that screening only offers benefits. On the other, there is the myth that screening is only offered to certain age groups due to <a href="http://www.thescottishsun.co.uk/scotsol/homepage/2153672/NHS-screening-cuts-betrayed-women-like-Jade-says-Sun-Columnist-Jane-Moore.html">financial restrictions</a>.</p>
<p>This superficial view has real and lasting implications for citizens, patients and health care professionals, leaving many people confused about screening. It needs to change.</p>
<p>Screening involves testing apparently healthy people to see if they have a higher risk of a disease. This means you can offer treatment or advice at an earlier stage, giving a greater chance of successfully dealing with or preventing the condition. Screening programmes are based on careful calculation, including who will benefit, what treatments are available and the level of accuracy of the tests.</p>
<p>Each screening programme is targeted to a specific subset of the population. For example, screening for diabetic eye disease only involves people with diabetes. Other effective screening <a href="http://www.nhs.uk/Livewell/Screening/Pages/screening.aspx">programmes in the UK</a> include looking for cystic fibrosis in newborn babies, or Hepatitis B and HIV in pregnant women.</p>
<p>But despite what you might read or hear, there are real risks of screening programmes, even in well-established programmes such as mammography. Sometimes screening produces false negative results, where people are mistakenly told they don’t have the disease. More common are the false positives, where people are mistakenly told they have the risk marker when they don’t, or when the condition that is identified would not have progressed, or was harmless. This means that any treatments they were then offered and underwent were unnecessary, with all of the emotional and health consequences that this brings.</p>
<h2>Risk versus benefit</h2>
<p>There is <a href="http://www.dailymail.co.uk/health/article-2958333/Would-mammogram-number-women-screened-breast-cancer-falls-year-new-study-reignites-debate-benefits-risks-test.html">heated debate</a> about the harm this causes. <a href="http://bit.ly/1TirDPu">For example</a>, in the case of UK women aged 50 screened for breast cancer for the next 20 years, <a href="https://www.harding-center.mpg.de/de/system/files/media/pdf/cee0305337891f79c011e70d3879c2e1/mammography_en_11-2014.pdf">one death</a> is prevented for about every three over-diagnosed cases identified and treated. And there is <a href="http://archinte.jamanetwork.com/article.aspx?articleid=2363025">no impact</a> on death overall from all causes.</p>
<p>I am saddened when I hear people discuss their distress about their own or their family member’s “cancer” diagnosis via screening when, for example, the breast cancer cells discovered haven’t developed the ability to spread. These “DCIS” cells look like cancer down a microscope but they don’t behave like cancer and might never have led to a problem.</p>
<p>Women are then put into a terrible dilemma. Do they live with uncertainty, or do they live with life-changing treatments? Would they have ever have started this journey had they realised the uncertainty? How do they get off the conveyor belt now they are on it? In many cases, they <a href="http://archinte.jamanetwork.com/article.aspx?articleid=1754987&resultClick=3#Discussion">do not even realise</a> that the life-changing mastectomy (or double mastectomy) was an adverse consequence of being screened. It seems counter-intuitive, but <a href="http://www.bmj.com/content/343/bmj.d4692">there is evidence</a> a mastectomy is less likely if you wait for symptoms instead of being screened </p>
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<span class="caption">Unbearable decision.</span>
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<p>Some men may have a prostate blood test that leads to a biopsy and then an operation that produces impotence. Were these operations necessary? How unbearable to wonder. Many of the screeners these men and women will meet on their journeys are also <a href="http://archinte.jamanetwork.com/article.aspx?articleid=1754987&resultClick=3#Discussion">not fully informed</a> about the limitations. Before starting on any screening journey, everyone should be told about the real risks and benefits in order to make their own, informed decisions.</p>
<p>The question of who should be invited for screening generates some of the most emotive and often misinformed discussion. <a href="http://www.itv.com/news/wales/2015-05-27/teenage-cancer-survivor-campaigns-to-lower-age-for-cervical-cancer-screening/">Campaigners and</a> <a href="http://www.reuters.com/article/2015/04/09/us-people-taylorswift-idUSKBN0N025U20150409">celebrities call for screening</a> in more people, more diseases and for longer with no mention of the impact and potential harms of doing so. It is vanishingly rare that they have any expertise in biology, medicine, science or uncertainty and yet their opinions that “more should be done” or “more could have been done” are given a great deal of airtime.</p>
<p>The conversations surrounding cervical screening are no exception. Currently cervical screening in the UK is only offered from the age of 25, but <a href="http://www.bbc.co.uk/news/uk-northern-ireland-foyle-west-29814206">media coverage</a> <a href="http://www.mirror.co.uk/news/uk-news/sophie-jones-petition-cervical-screening-3253376">and petitions</a> have demanded the cervical screening age be lowered to 20. But research has shown that screening this younger age group is ineffective. It <a href="http://www.bmj.com/content/339/bmj.b2968">does not prevent deaths</a> from cervical cancer and results in many false positives and overdiagnosis. </p>
<h2>No short cut</h2>
<p>Treatment of more and more women with minor cellular abnormalities in the cervix will lead to <a href="http://www.bmj.com/content/349/bmj.g6223">surgical damage</a> and to some cases of premature and damaged babies being born. The cervical screening programme on offer, as with all others, should be based solely on the balance of benefit and harm. It should not be unduly influenced by public discussion that only promotes a one-sided story of benefits. </p>
<p>Screening is not a short cut to health. It should not be for everyone. It should not be for all diseases. It should not be about screening more people for longer. It should only be offered when there are more benefits than risks. </p>
<p>The charity <a href="http://www.senseaboutscience.org">Sense About Science</a> has launched a new edition of <a href="http://www.senseaboutscience.org/pages/making-sense-of-screening.html">Making Sense of Screening</a> to tackle the widespread myths about screening programmes. I hope it will be shared among clinicians, health professionals and anyone interested or concerned about screening so that more people understand that simplistic calls for more screening are wrong. Harms always need to be weighed against benefits when making decisions about screening, whether at national programme or individual level.</p><img src="https://counter.theconversation.com/content/44257/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Susan Bewley is a trustee of HealthWatch, a charity 'for science and integrity in medicine' and contributed to Sense About Science's 'Making Sense of Screening' guide.</span></em></p>Screening may save lives but it comes with a cost - and sometimes unbearable decisions - that shouldn’t be underestimated.Susan Bewley, Professor of complex obstetrics, King's College LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/400362015-04-20T05:04:49Z2015-04-20T05:04:49ZThe mystery of breast cancer<p>For most of the common cancers, a major cause has been identified: smoking causes <a href="http://med.stanford.edu/biostatistics/abstract/RobertProctor_paper1.pdf">90% of lung cancer worldwide</a>, hepatitis viruses cause most liver cancer, <em>H pylori</em> bacteria <a href="http://www.ncbi.nlm.nih.gov/pubmed/24889903">causes stomach cancer</a>, Human papillomavirus causes almost all cases of <a href="http://www.cdc.gov/cancer/hpv/statistics/cases.htm">cervical cancer</a>, colon cancer is <a href="http://www.ncbi.nlm.nih.gov/pubmed/22158327">largely explained</a> by physical activity, diet and family history. </p>
<p>But for breast cancer, there is no smoking gun. It is almost unique among the common cancers of the world in that there is not a known major cause; there is no consensus among experts that proof of a major cause has been identified. </p>
<p>Yet, breast cancer is the most common form of cancer in <a href="http://www.who.int/mediacentre/factsheets/fs297/en/">women worldwide</a>. The risk <a href="http://globocan.iarc.fr/Pages/fact_sheets_cancer.aspx">is not equally distributed</a> around the globe, though. Women in North America and Northern Europe have long had five times the risk of women in Africa and Asia, though recently risk has been increasing fast in Africa and Asia for unknown reasons. </p>
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<span class="caption">Was it something I ate?</span>
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<h2>Is diet to blame?</h2>
<p>Up until about 20 years ago, we thought it was all about diet. As people abandon their local food sources and begin to eat highly processed foods with lots of fats, the hypothesis went, breast cancer was thought to be more likely to develop. </p>
<p>This hypothesis was logical because when researchers analyzed countries’ per capita fat consumption and breast cancer mortality rates, they found a <a href="http://cancerres.aacrjournals.org/content/35/11_Part_2/3374">strong correlation</a>. In addition, rats fed a high-fat diet are more prone to breast tumors. </p>
<p>By studying Japanese migrants to California, researchers found that the first generation had low risk like their parents in Japan, but then by the second and third generation, <a href="http://www.ncbi.nlm.nih.gov/pubmed/7742407">risk was as high</a> as white American women. So, the genetics of race did not account for the stark differences in the breast cancer risk between Asia and America. This was also consistent with the idea that the change in food from the lean Asian diet to the high-fat American diet causes cancer. So it all made sense.</p>
<p>Until it didn’t. </p>
<h2>Diet studies find that fat is not the answer</h2>
<p>Starting in the mid-1980s, large, well-done prospective studies of diet and breast cancer began to be reported, and they were uniformly negative. Fat in the diet of adult women <a href="http://www.ncbi.nlm.nih.gov/pubmed/3785347">had no impact</a> on breast cancer risk at all. </p>
<p>This was very surprising – and very disappointing. The evidence for other aspects of diet, like fruits and vegetables, has been <a href="http://www.ncbi.nlm.nih.gov/pubmed/24330083">mixed</a>, though alcohol consumption does increase risk modestly. It is also clear that heavier women are at higher risk after menopause which might implicate the total amount of calories consumed if not the composition of the diet. </p>
<p>There is a chance that early life dietary fat exposure, even in utero, <a href="http://www.ncbi.nlm.nih.gov/pubmed/9823005">may be important</a>, but it’s difficult to study in humans, so we don’t know much about how it might relate to breast cancer risk later in life. </p>
<p>If diet is not the major cause of breast cancer, then what else about modernization might be the culprit? </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/78094/original/image-20150415-31660-xtlhen.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/78094/original/image-20150415-31660-xtlhen.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/78094/original/image-20150415-31660-xtlhen.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/78094/original/image-20150415-31660-xtlhen.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/78094/original/image-20150415-31660-xtlhen.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/78094/original/image-20150415-31660-xtlhen.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/78094/original/image-20150415-31660-xtlhen.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Some risk factors, like exercise, can be modified.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-175183394/stock-photo-fit-sports-woman-jogging-at-park.html?src=h_0DMjDoxgREWJUukUoIEQ-1-0">Runner via www.shutterstock.com.</a></span>
</figcaption>
</figure>
<h2>Two kinds of risk factors: what we can modify, and what we can’t</h2>
<p>The factors shown to affect a woman’s risk for developing breast cancer fall into <a href="http://www.cancer.org/cancer/breastcancer/detailedguide/breast-cancer-risk-factors">two categories</a>. First, those that cannot be easily modified: age at menarche, age at birth of first child, family history, genes like BRCA1. And second, those that are modifiable: exercise, body weight, alcohol intake, night-work jobs. </p>
<p>The role of environmental pollution is controversial and also <a href="http://www.ncbi.nlm.nih.gov/pubmed/24818537">difficult to study</a>. The concern about chemicals, particularly endocrine disruptors, started after the realization that such chemicals could affect cancer risk in <a href="http://www.niehs.nih.gov/health/topics/agents/endocrine/">rodent models</a>. But in human studies the evidence is mixed.</p>
<p>Because child bearing at a young age and breast feeding reduce risk, the incidence throughout Africa, where birth rates tend to be higher, and where women start their families at younger ages, <a href="http://www.who.int/bulletin/volumes/91/9/13-020913/en/">has been lower</a>. </p>
<p>Death rates, however, from breast cancer in sub-Saharan Africa are now almost as high as in the developed world <a href="http://www.ncbi.nlm.nih.gov/pubmed/24604092">despite the incidence still being much lower</a>. This is because in Africa, women are diagnosed at a later stage of disease and also because there are far fewer treatment options.</p>
<p>The question is whether the known risk factors differ enough between the high-risk modern societies and the low-risk developing societies to account for the large differences in risk. The answer: probably not. Experts think that less than half the high risk in America is explained by the <a href="http://www.ncbi.nlm.nih.gov/pubmed/7473816">known risk factors</a>, and that these factors explain <a href="http://www.ncbi.nlm.nih.gov/pubmed/2228308">very little of the difference</a> in risk with Asia. </p>
<p>A related question is whether the high risk in America and Northern Europe is due to a combination of many known exposures, each of which affects risk a little bit, or mostly due to a major cause that has so far eluded detection. And maybe some of the known risk factors have a common cause which we don’t yet understand. </p>
<h2>Are we just finding more cancer?</h2>
<p>Since the 1980s, screening by mammography has accounted for some of the increase in incidence in the modern world compared to the developing world, but not nearly enough to explain the entire difference. About 20% of the cancers found by mammography are now believed to be of a type that would never have progressed beyond the very small early stage that mammography can detect. But the problem is that we can’t tell which are the benign <a href="http://jama.jamanetwork.com/article.aspx?articleid=1853165">ones and which are not</a>. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/78095/original/image-20150415-19648-cw521g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/78095/original/image-20150415-19648-cw521g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/78095/original/image-20150415-19648-cw521g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/78095/original/image-20150415-19648-cw521g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/78095/original/image-20150415-19648-cw521g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/78095/original/image-20150415-19648-cw521g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/78095/original/image-20150415-19648-cw521g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Electric light and shift work may be factors.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-146043281/stock-photo-side-view-of-a-young-woman-working-on-computer-in-dark-office.html?src=R6VnowHB7Nqr7vQwuzgxsg-1-19">Office worker via www.shutterstock.com.</a></span>
</figcaption>
</figure>
<h2>What about electric light?</h2>
<p>Electric light is a hallmark of modern life. So, maybe the introduction and increasing use of electricity to light the night accounts for a portion of the worldwide breast cancer burden.</p>
<p>This might be because our circadian rhythm is disrupted, which affects hormones that <a href="http://onlinelibrary.wiley.com/doi/10.3322/caac.21218/abstract">influence breast cancer development</a>. For example, electric light at night can trick the body into daytime physiology in which the hormone melatonin is suppressed; and melatonin has been <a href="http://www.ncbi.nlm.nih.gov/pubmed/16322268">shown</a> to have a strong inhibitory effect on human breast tumors growing in rats.</p>
<p>The theory is easy to state but difficult to test in a rigorous manner. Studies have shown that night-working women are at <a href="http://www.thelancet.com/journals/lanonc/article/PIIS1470-2045%2807%2970373-X/abstract">higher risk than day-working women</a>, which was the first prediction of the theory. </p>
<p>Other predictions are that blind women would be at lower risk, short sleepers would be at higher risk, and more highly lighted communities at night would have higher breast cancer incidence. Each of these has some modest support though <a href="http://www.ncbi.nlm.nih.gov/pubmed/19380369">none are conclusive</a>. What we do know is that electric light in the evening or at night can <a href="https://theconversation.com/a-dark-night-is-good-for-your-health-39161">disrupt our circadian rhythms</a>, and whether this harms our long term health, including risk of breast cancer, is not yet clear.</p>
<p>Whatever is going on, it’s important to find answers because breast cancer has become a scourge that now afflicts women all over the world in very large numbers, at almost two million new cases this year alone.</p><img src="https://counter.theconversation.com/content/40036/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Richard Stevens has received funding from the National Institute for Environmental Health Sciences.</span></em></p>Major causes have been identified for most common cancers, like liver and lung. But we still haven’t identified one for breast cancer.Richard G. "Bugs" Stevens, Professor, School of Medicine, University of ConnecticutLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/347002014-12-09T07:23:45Z2014-12-09T07:23:45ZHow does breast density impact on cancer screening?<figure><img src="https://images.theconversation.com/files/66693/original/image-20141209-6712-1evm4b1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">We're yet to find an alternative way to better detect breast cancer in women with dense breasts.</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-231227074/stock-photo-mammography-examination-hospital-background-with-technology-health-machine.html?src=I7c8Kyu33z1Lv4w5zQVYOA-1-55">CristinaMuraca/Shutterstock</a></span></figcaption></figure><p>We’ve known for some time that women with dense breasts are at higher risk of breast cancers that are difficult to detect by mammography. To address this problem, 19 US states have <a href="http://breastscreeningaustralia.com/2014/07/17/breast-density-inform-inconsistency-delivers-confusion/">introduced laws</a> requiring health providers to notify women whose mammograms show they have “dense breasts”.</p>
<p>These women are encouraged to discuss this finding with their doctor and, if necessary, have follow-up ultrasounds or magnetic resonance imaging scans to look for possible breast cancers. </p>
<p>But <a href="http://www.nzherald.co.nz/world/news/article.cfm?c_id=2&objectid=11371312">new US modelling</a> testing the impact of routine follow-up ultrasounds for women with dense breasts found the process would be costly, lead to unnecessary anxiety and deliver little benefit. </p>
<p>While we’re yet to find a better way to detect breast cancers in women with dense breasts, directing all women with dense breasts to have follow-up imaging might be an unwarranted and costly public health strategy.</p>
<h2>Why does density matter?</h2>
<p>“Breast density” does not refer to how hard a woman’s breasts feel. It refers to the white or bright areas of a mammogram and is more appropriately referred to as “mammographic density”.</p>
<p>Mammographic density is important for two reasons. First, and in the context of the US laws, the brighter areas on the mammogram can cover up existing breast tumours. This is referred to as “masking”. </p>
<p>Australian researchers have been studying the masking phenomenon for many years and <a href="http://www.abc.net.au/science/articles/2001/01/12/232048.htm?site=science/Askanexpert&topic=latest">have found</a> the use of hormone therapy could increase the problem for some women. Therefore an “all clear” from a mammogram can be a “false negative”. </p>
<p>Second, for women of the same age and body mass index, those with higher mammographic density are at greater risk of a future breast cancer. The one-quarter of women in the highest-density category are almost three times <a href="http://www.ncbi.nlm.nih.gov/pubmed/12239257">more likely</a> to develop breast cancer than the one-quarter of women in the lowest-density category.</p>
<p>The predictive power is not dramatic on a personal level, as it is for having a mutation in a breast cancer susceptibility gene such as BRCA1 or BRCA2. But because women vary so much in their mammographic density, on a population basis it is among the strongest risk factors for breast cancer. </p>
<h2>Genetic link</h2>
<p>In collaboration with BreastScreen services across Australia and colleagues in Canada, my research team undertook a large twin study and <a href="http://www.nejm.org/doi/full/10.1056/NEJMoa013390">found</a> genetic factors play an important role in breast density variation. </p>
<p>From this, we predicted that mammographic density explains about 10% of why breast cancer runs in families. New genetic studies are confirming this prediction.</p>
<p>We also <a href="https://minerva-access.unimelb.edu.au/handle/11343/35311">identified</a> the first gene that influences both mammographic density and breast cancer, called LSP1. A large international collaboration led by Associate Professor Jennifer Stone at the University of Western Australia has found at least ten more such genes. This research will soon be published.</p>
<p>We have also found that mammographic density measures that predict breast cancer risk “track” through life. This means mammographic density in early adulthood predicts mammographic density in mid-life, and hence breast cancer risk.</p>
<h2>Towards better detection</h2>
<p>We’re yet to find an alternative way to better detect breast cancer in women with dense breasts. But international researchers are working to:</p>
<ul>
<li><p>develop automated measures using digital mammograms that best predict breast cancer risk</p></li>
<li><p>develop optimal screening protocols (ages and times between mammograms) for women, depending on their mammographic density</p></li>
<li><p>determine the most cost-effective alternative screening strategies for women with mammographically dense breasts</p></li>
<li><p>implement these strategies in breast screening services, including those in developing countries in which breast cancer is becoming an increasingly important disease. </p></li>
</ul>
<p>While we’re making substantial progress in the first two areas, there is a long way to go for the last two.</p>
<p>Another area of research is to find out what can be done to lower a woman’s mammographic density and hence, it is hoped, her risk of breast cancer. </p>
<p>We know, for instance, that child birth gives a small but long-term reduction in breast cancer risk. During pregnancy, the breasts becomes mammographically dense, but after lactation the <a href="http://cebp.aacrjournals.org/content/early/2013/10/15/1055-9965.EPI-13-0481.full.pdf+html">density reduces</a> by an average of 7% when compared with the pre-pregnancy density. </p>
<p>There is also <a href="http://www.ncbi.nlm.nih.gov/pubmed/21483019">some evidence</a> that tamoxifen, a drug given to reduce breast cancer risk, especially for women who have had a breast cancer, might also reduce mammographic density. </p>
<p>Mammographic density also appears to explain why having a high body mass index in late adolescence is associated with being at lower risk of breast cancer.</p>
<p>So dense breasts are not a new phenomenon. Australian researchers and BreastScreen have been working hard for nearly two decades to understand and, most importantly, work out how to use this concept to reduce deaths from breast cancer. </p>
<p>With the increasing availability of digital mammography, breast density is more easily measured, and researchers continue to search for better ways to detect breast cancer in women with dense breasts. </p>
<p>The challenge now is to use mammographic density to help make breast screening more effective in preventing deaths from breast cancer, at lower financial cost and with fewer of the negative impacts inherent in all population-wide screening programs.</p><img src="https://counter.theconversation.com/content/34700/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>John Hopper receives funding from the National Breast Cancer Foundation, Cancer Council Australia, Cancer Australia, National Institutes of Health in the US, VicHealth.</span></em></p>We’ve known for some time that women with dense breasts are at higher risk of breast cancers that are difficult to detect by mammography. To address this problem, 19 US states have introduced laws requiring…John Hopper, NHMRC Australia Fellow, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/195242013-10-25T01:11:52Z2013-10-25T01:11:52Z#mamming meme opens young women up to screening harms<figure><img src="https://images.theconversation.com/files/33727/original/v8f2xhr6-1382659880.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Mamming involves resting breasts on a flat surface and taking a photo. </span> <span class="attribution"><span class="source">Ondra Anderle</span></span></figcaption></figure><p>Social media can help raise awareness of health issues, engaging people in discussion and encouraging them to take action. But thoughtless adherence to such trends has the potential to cause harm.</p>
<p>New ideas (or <a href="https://en.wikipedia.org/wiki/Meme">memes</a>) can spread quickly on platforms such as Twitter and Facebook. Mamming is such a new meme.</p>
<p>Mamming is the brain child of Michelle Lamont and Michele Jaret, two young women in the advertising industry. It involves resting (clothed) female (or even male) breasts on a flat surface. Then a photo is taken and sent off to Twitter and Instagram. </p>
<p>If you find this description not clear enough, this <a href="https://www.youtube.com/watch?v=zbP4h8Jud4A&feature=youtu.be">video clip</a> will show you how it’s done. Also, the <a href="http://www.thisismamming.com/#about-what">thisismamming website</a> provides further examples.</p>
<p>Mamming photos are tweeted to raise awareness of breast cancer, to reduce the awkwardness of mammograms, and to encourage women to participate in breast cancer screening. </p>
<p>Lamont and Jaret <a href="http://www.thisismamming.com/#about-what">propose</a> that “#Mamming is a chance for all* of us to show solidarity with the millions of women getting mammograms this Breast Cancer Awareness Month. Because when a woman reaches a certain age, doctors recommend that she get a mammogram to screen for the disease, and the procedure involves laying her boobs on the machine’s flat surface.”</p>
<p>It appears many young women, and some young men, have taken up the challenge and posted photos of their breasts on Twitter and Instagram. Several men on Twitter have greeted the new meme as a welcome distraction, while others have expressed their support for breast cancer awareness and screening.</p>
<p>So far, so good. But we should be careful about following this trend uncritically. Many people may not realise that breast cancer screening involves benefits as well as harms.</p>
<p>The Cochrane Collaboration did a <a href="http://summaries.cochrane.org/CD001877/screening-for-breast-cancer-with-mammography">systematic review of research evidence</a>, and found that for every 2,000 women invited for screening over ten years, one will avoid dying of breast cancer. But ten healthy women, who would not have been diagnosed if there had not been screened, would be treated unnecessarily. </p>
<p>And more than 200 women will experience psychological distress, including anxiety and uncertainty for years because of false positive findings.</p>
<p>The reason why this is of particular concern is that the women who have so far embraced the mamming meme are, for the most part, young. </p>
<p>In Australia, <a href="http://www.cancerscreening.gov.au/internet/screening/publishing.nsf/Content/breastscreen-about">breast cancer screening</a> until recently was recommended for women aged between 50 and 69 years. But <a href="http://www.aihw.gov.au/media-release-detail/?id=60129544955">data released today</a> shows that just over half (55%) of women in the target age group had a mammogram in 2010-2011. This age range has now been extended to 74 years. </p>
<p>In the United States, the <a href="http://www.cancer.org/cancer/breastcancer/moreinformation/breastcancerearlydetection/breast-cancer-early-detection-acs-recs">American Cancer Society</a> recommends that women start earlier, at 40, and continue to have mammograms every year.</p>
<p>In the <a href="http://www.patient.co.uk/health/breast-screening">United Kingdom</a>, women aged between 50 and 70 years (soon to be between 47 and 73) are routinely invited to breast cancer screening every three years. </p>
<p>Lamont and Jaret told <a href="http://www.huffingtonpost.co.uk/2013/10/23/mamming-internet-craze-breast-cancer-awareness_n_4147352.html">Huffington Post</a> that they hope “mamming reminds women to get screened, and maybe makes them feel a little less awkward about putting their boobs in the mammogram machine.” </p>
<p>And that’s what doesn’t fit: regular breast screening is not recommended for young women, yet mamming’s purpose is to remind women to get screened. The vast majority of women portrayed on the <a href="http://www.thisismamming.com/#about-what">thisismamming website</a> look younger than 35 years of age. </p>
<p>What’s more, the women who keep reminding each other by sharing their mamming photos on social media appear to be young women. </p>
<p>Will the trend make young women feel they should have a mammogram and risk unnecessary psychological distress and interventions, such as surgery? It’s unlikely that they blindly follow every craze but, at first sight, mamming appears to be in support of a worthwhile cause.</p>
<p>When Kylie Minogue’s diagnosis of breast cancer became public knowledge, there was a surge of young women participating in breast cancer screening.</p>
<p>We can only hope this craze dies down as quickly as it emerged. In the meantime, I’ll keep tweeting with the hash tag #mamming, pointing young women to the Nordic Cochrane Centre’s <a href="http://www.cochrane.dk/">mammography screening leaflet</a>. </p>
<p>If you’re on Twitter, why don’t you join me in setting the picture straight.</p><img src="https://counter.theconversation.com/content/19524/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Monika Merkes does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Social media can help raise awareness of health issues, engaging people in discussion and encouraging them to take action. But thoughtless adherence to such trends has the potential to cause harm. New…Monika Merkes, Honorary Associate, Australian Institute for Primary Care & Ageing, La Trobe UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/141592013-05-13T20:07:12Z2013-05-13T20:07:12ZA rational expansion of breast cancer screening<figure><img src="https://images.theconversation.com/files/23649/original/mzydq554-1368422575.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Based on current evidence, expanding these services is the right thing to do.</span> <span class="attribution"><span class="source">Image from shutterstock.com</span></span></figcaption></figure><p><em>In the ninth part of our series <a href="https://theconversation.com/topics/health-rationing">Health Rationing</a>, Stephen Duckett examines the government’s decision to extend the breast cancer screening program.</em></p>
<hr>
<p>As one of many pre-budget teasers, Health Minister Plibersek <a href="http://www.health.gov.au/internet/ministers/publishing.nsf/Content/mr-yr13-tp-tp039.htm">announced on Mother’s Day</a> that Australia’s breast screening program will be extended to target women aged 50 to 74 instead of the current age range of 50 to 69.</p>
<p>There may be political benefits from this A$55 million spend, but is it a good deal?</p>
<p>From an economic rationality point of view, the short answer is yes. But there may be a better way to achieve greater gains. </p>
<h2>Is breast screening worth it?</h2>
<p>Australia’s breast screening program was announced by then-prime minister Bob Hawke in the midst of the 1990 election campaign. </p>
<p>But the benefits of the program haven’t been entirely political. A <a href="http://www.cancerscreening.gov.au/internet/screening/publishing.nsf/Content/E158C94C6D5FA028CA25762A00029B8A/$File/Econ%20Eval.pdf">2009 cost effectiveness analysis</a> showed that the program cost A$38,302 for each year of life gained. That is a good deal compared to <a href="http://www.sph.uq.edu.au/docs/BODCE/ACE-P/ACE-Prevention_final_report.pdf">other health investments</a>. Dietary counselling from a GP
for people at greater than 5% risk of heart disease, for instance, costs about A$35,000 for every <a href="https://theconversation.com/comparing-apples-pears-and-hips-health-rationing-at-work-13785">disability adjusted life year</a> gained.</p>
<p>Although assumptions in cost effectiveness analysis of breast screening have been challenged because it doesn’t account for the the anxiety <a href="http://www.hta.ac.uk/project/2510.asp">created by screening programs</a>, this report is the best evidence we’ve got.</p>
<p>The government’s decision to extend the age range of women eligible can be seen as economically reasonable because of the reduced cost per year of life gained. Economic rationality and rationing is not a euphemism for budget cutting. Based on current evidence, expanding these services is the right thing to do.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/23639/original/xq982zhy-1368421319.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/23639/original/xq982zhy-1368421319.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/23639/original/xq982zhy-1368421319.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=206&fit=crop&dpr=1 600w, https://images.theconversation.com/files/23639/original/xq982zhy-1368421319.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=206&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/23639/original/xq982zhy-1368421319.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=206&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/23639/original/xq982zhy-1368421319.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=259&fit=crop&dpr=1 754w, https://images.theconversation.com/files/23639/original/xq982zhy-1368421319.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=259&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/23639/original/xq982zhy-1368421319.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=259&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Comparative cost per year of life gained of different policy designs.</span>
<span class="attribution"><span class="source">2009 Cost effectiveness report</span></span>
</figcaption>
</figure>
<p>But here’s the rub. Extending the age range down to 45 and up to 74 is even better on cost-effectiveness criteria. With that policy, the cost per year of life gained from screening would be A$37,612 compared to the current A$38,302 – a 2% improvement. Small, yes, but important in the overall scheme of things.</p>
<p>Cost effectiveness isn’t the only relevant criterion, though, even for the econocrat. Extending the age range both upward and downward would cost much more money than just an upward change. In tight budgetary times the larger extension, although economically worthwhile, may have been a budget step too far.</p>
<h2>Roads not taken</h2>
<p>Yet, if increasing the age range were combined with efforts to cut the cost of screening, we might be able afford the best of both worlds: even more breast cancer screening without hurting the budget bottom line. Cost-effective expansions and budget integrity might both have been feasible.</p>
<p>The 2009 cost effectiveness report also examined changes to current practice and identified several ways to save money, while still saving lives. Increasing the screening interval from two to three years is certainly cost effective and would save significantly on budget outlays. The government could easily afford an age range expansion in both directions if that change were implemented.</p>
<p>Changes in who can conduct and read mammograms are also cost effective. Currently, every mammogram is examined independently by two radiologists. One cheaper and more cost-effective option assessed was to have the second reading done by a specially trained reader. Changes in who takes the mammograms – a radiographer assistant rather than a radiographer – would also lower costs.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/23640/original/8ccdrt56-1368421319.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/23640/original/8ccdrt56-1368421319.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/23640/original/8ccdrt56-1368421319.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=361&fit=crop&dpr=1 600w, https://images.theconversation.com/files/23640/original/8ccdrt56-1368421319.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=361&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/23640/original/8ccdrt56-1368421319.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=361&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/23640/original/8ccdrt56-1368421319.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=454&fit=crop&dpr=1 754w, https://images.theconversation.com/files/23640/original/8ccdrt56-1368421319.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=454&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/23640/original/8ccdrt56-1368421319.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=454&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">Grattan Institute</span></span>
</figcaption>
</figure>
<p>There is still some controversy about breast screening and new evidence is becoming available every day. The 2009 cost-effectiveness study was a “modelling” study, not an assessment in the real world.
In contrast to the Australian approach of simply announcing an expansion of breast screening, a similar expansion in the English National Health Service was accompanied by a <a href="http://www.controlled-trials.com/ISRCTN33292440">randomised controlled trial</a> to allow a full evaluation of the new policy. </p>
<p>It’s puzzling why a similar strategy was not followed here, especially in the light of <a href="http://www.mckeonreview.org.au/">recent calls</a> for more health services research in Australia to contribute to policy development.</p>
<h2>Burgeoning health outlays</h2>
<p>Health expenditure is <a href="https://theconversation.com/tough-choices-how-to-rein-in-australias-rising-health-bill-13658">rising rapidly</a>. Budget setting is about priority setting (the soft way to say “rationing”). But the rationing discussion should follow, not replace or precede, the efficiency discussion. The extra money to expand screening to wider age groups could have been offset completely by improved efficiency.</p>
<p>Current policy settings in breast screening “ration” the public program to women aged 50-69. The government has just announced a new “rationing” regime, to target women 50-74, and this indeed is a rational expansion, as far as it goes.</p>
<p>But the real rationing question is: in hard economic times, why aren’t we pursuing other breast-screening initiatives – such as changing the screening interval and using a different mix of health professionals – that are more economically rational and save more money?</p>
<p><strong><em>This is the ninth part of our series <a href="https://theconversation.com/topics/health-rationing">Health Rationing</a>. Click on the links below to read the other instalments:</em></strong></p>
<p><strong>Part one:</strong> <a href="https://theconversation.com/tough-choices-how-to-rein-in-australias-rising-health-bill-13658">Tough choices: how to rein in Australia’s rising health bill</a><br> <strong>Part two:</strong> <a href="https://theconversation.com/explainer-what-is-health-rationing-13667">Explainer: what is health rationing?</a><br>
<strong>Part three:</strong> <a href="https://theconversation.com/a-conversation-that-promises-savings-worth-dying-for-13710">A conversation that promises savings worth dying for</a><br>
<strong>Part four:</strong> <a href="https://theconversation.com/phase-out-gp-consultation-fees-for-a-better-medicare-13690">Phase out GP consultation fees for a better Medicare</a><br>
<strong>Part five:</strong> <a href="https://theconversation.com/focus-on-prevention-to-control-the-growing-health-budget-13665">Focus on prevention to control the growing health budget</a><br>
<strong>Part six:</strong> <a href="https://theconversation.com/health-funding-under-the-microscope-but-what-should-we-pay-for-13788">Health funding under the microscope – but what should we pay for?</a><br>
<strong>Part seven:</strong> <a href="https://theconversation.com/comparing-apples-pears-and-hips-health-rationing-at-work-13785">Comparing apples, pears and hips: health rationing at work</a><br>
<strong>Part eight:</strong> <a href="https://theconversation.com/who-gets-a-piece-of-the-pie-spending-the-health-budget-fairly-13997">Who gets a piece of the pie? Spending the health budget fairly</a></p><img src="https://counter.theconversation.com/content/14159/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Stephen Duckett does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>In the ninth part of our series Health Rationing, Stephen Duckett examines the government’s decision to extend the breast cancer screening program. As one of many pre-budget teasers, Health Minister Plibersek…Stephen Duckett, Director, Health Program, Grattan InstituteLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/105312012-11-18T19:10:22Z2012-11-18T19:10:22ZIs routine breast cancer screening doing more harm than good?<figure><img src="https://images.theconversation.com/files/17594/original/sd6ypdhw-1352854005.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Even without routine mammographs, women with a family history of the disease should be screened.</span> <span class="attribution"><span class="source">Zanthia</span></span></figcaption></figure><p>Public discussion about the risks of over-diagnosis of breast cancer have left some women wondering whether they should take part in the government’s breast screening program.</p>
<p>Let’s take a look at what the evidence says and how women might be enabled to make their own decisions about whether to participate.</p>
<p>Last year Sir Michael Marmot, Professor of Epidemiology and Public Health at University College London, was asked to chair an independent panel to review the benefits and harms of screening mammography in the United Kingdom. The panel focused on the findings from randomised trials, even though most of these trials were carried out a long time ago, in the 1970s and 1980s. </p>
<p>A <a href="http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(12)61611-0/abstract">report on the findings</a> of the review and an <a href="http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(12)61775-9/fulltext?elsca1=ETOC-LANCET&elsca2=email&elsca3=E24A35F">accompanying editorial</a> were published in the Lancet late last month. In summary, the report said that screening resulted in an estimated ratio of cases over-diagnosed, to deaths from breast cancer prevented, of 3:1. An <a href="http://jnci.oxfordjournals.org/content/102/9/605.abstract">over-diagnosed case</a> is one where screening has identified a breast cancer that will never cause harm. </p>
<p>As it is not currently possible to distinguish breast cancer identified through screening which will never cause harm from cancer that will, all breast cancer identified by screening is treated - with surgery and various combinations of radiotherapy, chemotherapy, endocrine and biologic therapies. </p>
<p>A woman treated needlessly will have no way of knowing that her cancer was harmless and that her well-being has been sacrificed, without her knowledge or consent, for the sake of others who may have benefited from screening.</p>
<h2>Assessing the benefits of screening</h2>
<p>The benefits of screening appear to have been over-estimated. </p>
<p>Advances in treatment have changed the outlook for women with breast cancer so profoundly over the past two decades that the potential for screening to further reduce deaths from breast cancer has been <a href="http://www.ncbi.nlm.nih.gov/pubmed/21956213">considerably reduced</a> since the original randomised trials were performed. </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/17597/original/38hshd4y-1352856418.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/17597/original/38hshd4y-1352856418.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/17597/original/38hshd4y-1352856418.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/17597/original/38hshd4y-1352856418.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/17597/original/38hshd4y-1352856418.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/17597/original/38hshd4y-1352856418.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/17597/original/38hshd4y-1352856418.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Women need to understand the risk of over-diagnosis.</span>
<span class="attribution"><span class="source">MBK Marjie</span></span>
</figcaption>
</figure>
<p>Furthermore, limiting the estimated benefit to reduced deaths from breast cancer is <a href="http://www.ncbi.nlm.nih.gov/pubmed/16360786">misleading</a> because radiotherapy after surgery for breast cancer materially increases the risk of dying from heart disease. </p>
<p>The magnitude of overdiagnosis has also been underestimated. An estimate of overdiagnosis from Australia – adjusted for confounders and lead time and assuming 60% of invited women attend – found an over-diagnosis rate of 30% to 40% depending on the expected incidence without screening, rather than the 19% in the <a href="http://www.ncbi.nlm.nih.gov/pubmed/19894130">Lancet report</a>. </p>
<p>The Nordic Cochrane Center <a href="http://www.cochrane.org/news/blog/mammography-screening-ten-years-reflections-decade-2001-review">review of screening mammography</a> has estimated the ratio of cases over-diagnosed to deaths from breast cancer prevented at 10:1. Our estimate of the ratio in Australia, using a lower estimate of deaths prevented due to the <a href="http://www.ncbi.nlm.nih.gov/pubmed/21956213">impact of improved treatment</a> and the higher rate of over-diagnosis, is closer to 15:1. </p>
<p>The clear message is that over-diagnosis exists, it happens regularly as part of the screening process and women need to understand this.</p>
<h2>An informed decision</h2>
<p>When an asymptomatic woman requests screening mammography through her doctor or when a doctor recommends that an asymptomatic woman be screened, the doctor has a responsibility to inform her about the potential harms and benefits so she can decide whether she will have the mammogram in the context of her situation and preferences. </p>
<p>But when a woman receives an invitation for screening from a government body that makes little or no reference to screening-related harm, she may reasonably expect that that there is no real likelihood of harm. It could be argued that the weight of responsibility for full and frank disclosure of risks and benefits is even greater when the invitation comes from a trusted government agency that has been historically responsible for promoting screening. </p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/17596/original/ghmndvwy-1352856418.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/17596/original/ghmndvwy-1352856418.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=815&fit=crop&dpr=1 600w, https://images.theconversation.com/files/17596/original/ghmndvwy-1352856418.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=815&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/17596/original/ghmndvwy-1352856418.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=815&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/17596/original/ghmndvwy-1352856418.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1025&fit=crop&dpr=1 754w, https://images.theconversation.com/files/17596/original/ghmndvwy-1352856418.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1025&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/17596/original/ghmndvwy-1352856418.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1025&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Women can still be screened for breast cancer without routine invitations.</span>
<span class="attribution"><span class="source">Topeka Shawnee County Public Library</span></span>
</figcaption>
</figure>
<p>It’s time to review the routine invitation for screening to all women aged 50 to 69 years. </p>
<p>The <a href="http://www.aihw.gov.au/publication-detail/?id=6442468276">proportion of women</a> in the invited age group who currently attend for screening in Australia is between 50% and 60% so not all women currently respond to the invitation by attending. </p>
<p>Stopping the routine invitation for screening would not prevent women being screened. Women with a high risk of cancer - those with a family or personal history of breast cancer – should still be screened. There may be others who should consider screening because they have a combination of <a href="http://www.cancer.org/cancer/breastcancer/detailedguide/breast-cancer-risk-factors">less powerful risk factors</a> which might put them at above average risk. </p>
<p>Other women, not at above-average risk, could request screening if this is what they want. </p>
<p>If women elect <em>not</em> to be screened and only enter the medical system when a clinical problem presents itself, they can be reassured that they will have the benefit of the recent improvements in breast cancer treatment.</p>
<h2>Next steps</h2>
<p>Government should undertake a review of the invitation for screening. But this will take time.</p>
<p>For the time being, it is imperative that all women be provided with comprehensive information about the disadvantages as well as the advantages of mammographic screening. The <a href="http://www.cochrane.dk/screening/mammography-leaflet.pdf">pamphlet</a> produced by the Nordic Cochrane Center, which presents the information in terms of the impact of screening on absolute risks and benefits, would make an excellent model. </p>
<p>But a pamphlet alone is insufficient. Given the risks, each woman must be given the opportunity to discuss her options and decide what is best for her, with those who are in a position to provide accurate and helpful advice.</p><img src="https://counter.theconversation.com/content/10531/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robin Bell receives funding from the Victorian Cancer Agency, the BUPA Health Foundation and the National Health and Medical Research Council of Australia.</span></em></p><p class="fine-print"><em><span>Michael Baum's department is funded by HTA, with an additional educational grant from Carl Zeiss.</span></em></p><p class="fine-print"><em><span>Bebe Loff and Robert Burton do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Public discussion about the risks of over-diagnosis of breast cancer have left some women wondering whether they should take part in the government’s breast screening program. Let’s take a look at what…Robin Bell, Professor & Deputy Director, Women's Health Program, School of Public Health and Preventive Medicine, Monash UniversityBebe Loff, Associate Professor and Head of Human Rights & Bioethics, Monash UniversityMichael Baum, Emeritus Professor of Surgery, UCLRobert Burton, Professor School of Public Health and Preventive Medicine, Monash UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/73962012-09-10T20:25:03Z2012-09-10T20:25:03ZOver-diagnosis and breast cancer screening: a case study<figure><img src="https://images.theconversation.com/files/15291/original/89ysp677-1347258264.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Women need to be made aware of over-diagnosis and given enough information to make up their own minds about screening.</span> <span class="attribution"><span class="source">Johan/Flickr</span></span></figcaption></figure><p><em>OVER-DIAGNOSIS EPIDEMIC – Today Robin Bell and Robert Burton examine breast cancer to evaluate the role of population-wide screening in over-diagnosis.</em></p>
<p>Since the national <a href="http://www.aihw.gov.au/WorkArea/DownloadAsset.aspx?id=6442454634">screening mammography program</a> (Breastscreen) began in Australia in 1991, <a href="http://www.aihw.gov.au/data">mortality from breast cancer</a> has declined by 28%. We wanted to know how much of this improvement was due to Breastscreen and how much was due to advances in breast cancer treatment.</p>
<p>This is an important question to ask in light of the recent passionate debate about the benefits and harms of mammographic screening in <a href="http://www.bmj.com/content/340/bmj.c3106?tab=responses">medical literature</a> as well as in the lay <a href="http://www.theage.com.au/national/behind-the-screen-20111103-1mxrh.html">press</a>. We published an <a href="http://www.ncbi.nlm.nih.gov/pubmed/21956213">analysis</a> that addressed this issue using three different approaches.</p>
<h2>Who avoids breast cancer death?</h2>
<p>We started by comparing the relative reductions in breast cancer-specific mortality between 1991 and 2007 (the latest data year available) in women across different age groups. We know women aged 50 to 69 years were invited to screen, so their uptake of mammographic screening should have been higher than other age groups. So if screening was important, this is where we would expect to see the most impact.</p>
<p>But what we found was that the greatest relative reduction in breast cancer mortality (44%) occurred in the youngest age group. These women (aged 40 to 49 years) are not invited for screening. In contrast, women aged 60 to 69 years, who <em>are</em> invited to screen, had the smallest relative reduction in mortality (19%). </p>
<p>Given that three times as many women aged 60 to 69 (about 60%) participated in Breastscreen (compared to 20% of women aged 40 to 49 years), our finding <em>is not consistent</em> with screening having a major impact on the reduction in breast cancer mortality since 1991.</p>
<h2>When was mortality reduced?</h2>
<p>We then considered <em>when</em> Breastscreen could have had an impact on breast cancer mortality between 1991 and 2007. </p>
<p>The proportion of invited women who attended for screening didn’t exceed 50% until 1996. And we know from randomised trials of screening that the impact of screening on mortality was not seen for four to six years after the commencement of the trials (they had an even higher level of <a href="http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(02)08020-0/fulltext">participation of 70% and more</a>). </p>
<p>So <a href="http://www.ncbi.nlm.nih.gov/pubmed/21956213">we compared the reductions</a> in mortality that occurred in two time periods – (1) between 1991 and 1999 when we wouldn’t have expected Breastscreen to have an impact and (2) between 2000 and 2007 when the impact of Breastscreen would’ve been expected. </p>
<p>For women invited for screening (50 to 69 years), most of the reduction in mortality that occurred between 1991 and 2007 took place prior 2000. The reduction was <em>before</em> the impact of screening could be expected. </p>
<p>Only about a third of the total 28% reduction in breast cancer mortality seen in this age-group over the full time period occurred after 1999 (9%). This finding is also inconsistent with mammographic screening having a major impact on the observed reduction in breast cancer mortality since 1991.</p>
<h2>Improved treatment</h2>
<p>Finally, we used a number of different data sources to estimate the likely impact on breast cancer mortality of changes in the use of <a href="http://www.cancer.gov/cancertopics/factsheet/Therapy/adjuvant-breast">adjuvant chemo</a> - and <a href="http://breastcancer.about.com/lw/Health-Medicine/Conditions-and-diseases/Endocrine-Treatments-for-Breast-Cancer.htm">endocrine therapy</a> over the same time period. We obtained published data from the Early Breast Cancer Trialists’ Collaborative Group (<a href="http://www.ncbi.nlm.nih.gov/pubmed/15894097">EBCTCG</a>) to provide the <a href="http://www.ncbi.nlm.nih.gov/pubmed/21802721">estimated impact</a> of regimens of chemo and endocrine therapy on women in different age groups with early breast cancer. </p>
<p>We used this data, together with data from a population-based <a href="http://onlinelibrary.wiley.com/doi/10.1002/cncr.20401/abstract">survey</a> of women treated for early breast cancer in Victoria in 1999, to calculate the impact the use of adjuvant chemo- and endocrine therapy could have had on breast cancer mortality in these women. We found that the adjuvant therapy Victorian women received in 1999 could have produced a mortality reduction of about 26% in women in the age group invited to screen. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/15283/original/38jdcdv4-1347257115.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/15283/original/38jdcdv4-1347257115.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/15283/original/38jdcdv4-1347257115.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/15283/original/38jdcdv4-1347257115.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/15283/original/38jdcdv4-1347257115.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/15283/original/38jdcdv4-1347257115.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/15283/original/38jdcdv4-1347257115.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Diagnosis comes with its own worries and stresses.</span>
<span class="attribution"><span class="source">Ronny-André Bendiksen</span></span>
</figcaption>
</figure>
<p>Indeed, improvements in the treatment of breast cancer could explain almost all of the reduction in breast cancer mortality that has occurred in women invited to screen since 1991.</p>
<p>We estimate mammographic screening is responsible for a minority of the reduction in breast cancer-specific mortality seen in Australia since 1991 and that advances in adjuvant therapies adequately explain the majority of the observed mortality reduction.</p>
<h2>Breast cancer and over-diagnosis</h2>
<p>A modest reduction in mortality as a result of mammographic screening would seem acceptable if it were not for the issue of over-diagnosis. Over-diagnosis is the diagnosis and treatment of breast cancer that would have never have made a woman ill in her lifetime – she would never have known about it if she had not been screened. </p>
<p>The extent of the problem of breast cancer over-diagnosis has been estimated in the <a href="http://www.ncbi.nlm.nih.gov/pubmed/21249649">Cochrane review of screening mammography</a> at 30%, based on the randomised trials. In Australia, based on increases in new case rates, over-diagnosis was estimated at 30% to 40% in the women aged 50 to 69 years invited to screen in New South Wales in <a href="https://www.mja.com.au/journal/2012/196/1/do-benefits-screening-mammography-outweigh-harms-overdiagnosis-and-unnecessary-0">2001 and 2002</a>. </p>
<p>Putting their estimates of the relative mortality reduction in breast cancer (15%) and over-diagnosis (30%) together to calculate the balance of benefits versus harms, <a href="http://www.ncbi.nlm.nih.gov/pubmed/21249649">the Cochrane review summarised</a>:</p>
<blockquote>
<p>“… for every 2000 women invited for screening throughout 10 years, one will have her life prolonged. In addition, 10 healthy women, who would not have been diagnosed if there had not been screening, will be diagnosed as breast cancer patients and will be treated unnecessarily.”</p>
</blockquote>
<p>Our estimate of the likely breast cancer-specific <a href="http://www.ncbi.nlm.nih.gov/pubmed/21956213">mortality reduction from screening</a> in women aged 50 to 69 years (9%) and the New South Wales estimates of 30% to 40% over-diagnosis <a href="http://www.ncbi.nlm.nih.gov/pubmed/19894130">in this age group are similar</a> to the Cochrane estimates. </p>
<p>Based on these Australian estimates and the incidence and mortality of breast cancer in women aged 50 to 69 years in 2007, we know that for every death from breast cancer prevented, 15 healthy women, who wouldn’t have been diagnosed if they hadn’t been screened, will be diagnosed as having invasive breast cancer and will be treated unnecessarily.</p>
<p>Although there’s considerable argument about the exact extent of over-diagnosis, most estimates find the balance of lives saved to cases over-diagnosed and treated unnecessarily unfavourable, with more women over-diagnosed than saved.</p>
<p>We believe that the decision to invite women for screening should be reviewed with the aim of ceasing the standard invitation for screening. As women aged 50 to 69 years have been invited for screening for 20 years now, a change in policy may take some time to work through. </p>
<p>In the meantime, women need to be made aware of the issue of over-diagnosis and the information provided to those invited for mammographic screening needs to be better balanced between benefits and harms so they can make up their own minds about whether to be screened.</p>
<p><em>Have you or someone you know been over-diagnosed? Share your story below or <a href="mailto:reema.rattan@theconversation.edu.au">email</a> the series editor.</em></p>
<p><em>This is part two of our series on over-diagnosis, click on the links below to read other articles:</em></p>
<p><em><strong>Part one:</strong> <a href="https://theconversation.com/preventing-over-diagnosis-how-to-stop-harming-the-healthy-8569">Preventing over-diagnosis: how to stop harming the healthy</a></em></p>
<p><em><strong>Part three:</strong> <a href="https://theconversation.com/the-perils-of-pre-diseases-forgetfulness-mild-cognitive-impairment-and-pre-dementia-8702">The perils of pre-diseases: forgetfulness, mild cognitive impairment and pre-dementia</a></em></p>
<p><em><strong>Part four:</strong> <a href="https://theconversation.com/how-genetic-testing-is-swelling-the-ranks-of-the-worried-well-9080">How genetic testing is swelling the ranks of the ‘worried well’</a></em></p>
<p><em><strong>Part five:</strong> <a href="https://theconversation.com/psa-screening-and-prostate-cancer-over-diagnosis-8568">PSA screening and prostate cancer over-diagnosis</a></em></p>
<p><em><strong>Part six:</strong> <a href="https://theconversation.com/over-diagnosis-the-view-from-inside-primary-care-8889">Over-diagnosis: the view from inside primary care</a></em></p>
<p><em><strong>Part seven:</strong> <a href="https://theconversation.com/moving-the-diagnostic-goalposts-medicalising-adhd-8675">Moving the diagnostic goalposts: medicalising ADHD</a></em></p>
<p><em><strong>Part eight:</strong> <a href="https://theconversation.com/the-ethics-of-over-diagnosis-risk-and-responsibility-in-medicine-9054">The ethics of over-diagnosis: risk and responsibility in medicine</a></em></p>
<p><em><strong>Part nine:</strong> <a href="https://theconversation.com/ending-over-diagnosis-how-to-help-without-harming-9633">Ending over-diagnosis: how to help without harming</a></em></p><img src="https://counter.theconversation.com/content/7396/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robin Bell receives funding from the Victorian Cancer Agency, the BUPA Health Foundation and the National Health and Medical Research Council of Australia.</span></em></p><p class="fine-print"><em><span>Robert Burton does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>OVER-DIAGNOSIS EPIDEMIC – Today Robin Bell and Robert Burton examine breast cancer to evaluate the role of population-wide screening in over-diagnosis. Since the national screening mammography program…Robin Bell, Professor & Deputy Director, Women's Health Program, School of Public Health and Preventive Medicine, Monash UniversityRobert Burton, Professor School of Public Health and Preventive Medicine, Monash UniversityLicensed as Creative Commons – attribution, no derivatives.