Celebrities have taken to “live” mammograms on television, undergoing this usually very private procedure in a rather public way. This includes Today show co-host Lisa Wilkinson, and news presenter, Georgie Gardner.
In the United States, Good Morning America host, Amy Robach, had a television mammogram, which led to a diagnosis of breast cancer and a double mastectomy.
These women have a simple message that’s easy to embrace – mammography screening saves lives. Sadly, it’s not that simple.
Imagine 1,000 average-risk women aged 50, with no breast symptoms, who choose to have a mammogram every two years until age 69. Approximately eight of these women will die from breast cancer.
Now imagine another 1,000 identical women who don’t get screened. Approximately 12 of these women will die due to breast cancer.
This means if 1,000 average-risk women are screened every two years from the age of 50 to 69, four of them will avoid a breast cancer death. Put another way, screening every two years for 20 years reduces the average woman’s risk of dying from breast cancer by a third, from 1.2% to 0.8%.
Saving four women in every 1,000 from breast cancer death is of enormous value, but what happens to the other 996 who don’t receive any benefit from screening?
The vast majority of women might feel incredibly relieved if they receive a negative test result after a mammogram. But we know that women often overestimate their risk of getting breast cancer, a perception that may be enhanced by screening program promotions and the publicity generated by celebrities.
If they were made aware of the figures above, they could rest assured that the threat of death is relatively small – 1.2% of women aged 50 will die from breast cancer over the next 20 years even without screening, and 0.8% with screening.
Most women don’t realise they’re more likely to die from lung cancer or heart disease because breast screening promotions have been very good at highlighting the benefits of early detection while inadequately addressing the risks.
It’s also the case that the figures above might be an optimistic interpretation of 20- to 50-year-old data from the other side of the world. It’s possible that now, with much better treatment available and much more breast cancer awareness, screening saves far fewer lives than this estimate suggests.
And the harms?
In general, people are enthusiastic about cancer screening because they’re unprepared for what happens if an abnormality is detected. The paradox of screening is this: an abnormal result could save us, but also harm us.
The most common problem experienced by screened women is a false positive result; when a test raises suspicion of cancer but no cancer is found with further testing. Lisa Wilkinson experienced this after her on-air mammogram.
If a woman has a mammogram every two years for 20 years, there’s a 41% chance she will experience at least one false positive result. That’s almost one in two women. These healthy women then undergo further investigations to determine that they do not, in fact, have cancer.
They can suffer from psychological harm long after the initial scare of the false positive result. This harm includes anxiety and a state of mind somewhere between women with a normal mammogram and those with a breast cancer diagnosis.
The danger of overdiagnosis
The most challenging issue for anyone grappling with breast screening is overdiagnosis.
Women who are diagnosed with breast cancer through screening (such as Amy Robach) believe the mammogram saved their life. Sometimes this is true. Unfortunately, it’s more likely to be untrue and these women may have actually been overdiagnosed.
Overdiagnosis is when mammography detects small cancers that, if left alone, would not cause any symptoms or death. Women who undergo screening every two years for 20 years are three times more likely to be overdiagnosed than have their life saved.
This concept is counterintuitive because it’s at odds with our general understanding of cancer as a dread disease. That is, we’re used to thinking of breast cancer as uniformly lethal if left untreated.
But studies increasingly show that finding tiny cancers doesn’t necessarily translate into saving lives.
While the estimate of overdiagnosis is uncertain, the pattern is clear. Research from the United States, the United Kingdom, and Australia shows it’s more common for women to be overdiagnosed than have their life saved by screening.
This wouldn’t be such a problem if breast cancer treatment was easy, say a tablet or injection with few side effects. But the treatment is complex and difficult; surgery, radiotherapy, chemotherapy, and cancer drugs are physically and psychologically damaging.
So these overdiagnosed women are harmed due to over-treatment – they receive treatment for cancers that don’t need to be fixed.
With great power…
This information usually comes as a surprise to most people. Indeed, some women mistakenly believe that mammograms actually prevent breast cancer; Georgie Gardner, for instance, said screening is a vital tool for preventing breast cancer on television during her on-air mammogram.
Mammograms and their benefits have been heavily promoted by screening programs, charities and celebrities while the science behind the harms has been largely ignored.
Efforts may go beyond persuasion and make women feel irresponsible and guilty to convince them to have a mammogram.
In a recent article about Wilkinson’s on-air mammogram in the Herald Sun, journalist Tory Maguire said refusing a free mammogram was “stupid” and “selfish”. She quotes National Breast Cancer Foundation CEO Carole Renouf suggesting that women who decline the offer “endanger” their life.
But independent recommendations about breast screening acknowledge the harms and support the need for better, more balanced information so women know what they are signing up for.
When celebrities have a mammogram on television, the world watches. We have no doubt that Lisa Wilkinson, Georgie Gardner and Amy Robach had the very best intentions. But rather than using their fame and influence to persuade, they could start a healthy discussion about screening.
This would help women understand that there are harms, as well as benefits, from breast screening. And the trade-offs for both.