I do enjoy this excellent science that looks at all aspects and recommends against fear-mongering that pushes people into unnecessary medical treatment.

The standards of evidence for screening, and for drugs and medical procedures are very high and represent a lot of intelligent work by many people over a long period.

I'd like to see the same standard of evidence based medicine applied to another public health issue, that of bicycle helmet laws, which compares the harm done by discouraging health-giving exercise to the benefit of avoided head injuries. There is a growing body of evidence that the overall effect of Australia's laws is harmful, see for example Prof de Jong's paper:
http://papers.ssrn.com/sol3/papers.cfm?abstract_id=1368064
Elsewhere the Prof has estimated the break-even point for health outcomes in Australia would be a drop of as little as 2% in cycling rates, beyond which the law is harmful to health overall.

Surveys show around 1in 5 Australians cite helmet law as detering them from riding a bicycle. That's roughly equal to the number of people riding once a week or more. The effect on public health expenditure has conservatively been estimated (again by Prof de Jong) at around $0.5Bn per annum.

Governments are unwilling to review the evidence in any meaningful way. The impetus to change this harmful law needs to come from public health professionals who are concerned about rising rates of disease and mortality due to lack of exercise - 16,000 premature deaths each year in Australia according to the Heart Foundation.

I find the begining of this article unclear, I quote from it.."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 – " if this is so then how can we be having this conversation? It doesn't make sense! Also the recent British exposure of a doctor making his money from unnecessary lump excisions by telling women they had cancer that could kill them, and the experts in the field reviewing hundreds of cases have said to many they know it wouldn't have been life threatening. So can't 'experts' tell whether a cancer is potentially lethal, why does this article state they cannot? I myself am concerned about the level of radiation used to do this screening, as opposed to ultrasound, which a friend of mine had after an x-ray found something anyway. Obviously X-rays are cheaper, however extremely painful by what friends have said especially the small breasted.

Forgive me, but I don't understand this: "all breast cancer identified by screening is treated – with surgery and various combinations of radiotherapy, chemotherapy, endocrine and biologic therapies."

Do you mean post biopsy or other confirmatory diagnostic procedures after screening mammography? I'm assuming anything previous cannot be designated 'breast cancer' but correct me if I'm wrong. And . . .

"An over-diagnosed case is one where screening has identified a breast cancer that will never cause harm."

If so, do you mean that there are many false positives after biopsy or other diagnostic follow-ups to screening mammograms, or do you mean there are many false positives after mammogram screens?

There is no mention here of thermography as an alternative to mammography. Mammography pumps x-rays into the tissue, thermography finds possible cancer hot-spots earlier, and does no harm. Of course, in the UK we have to pay for it, as only the x-rays come free on our health system.

I think the article is an excellent summary of the present situation except for one point: I think the benefits of screening are overstated.

In fact I believe there is no proof that screening saves any lives.

The UK Review Panel noted that none of the 11 randomised controlled trials evaluating screening had sufficient power to provide an outcome on whether or not there was any reduction in “deaths from all causes” following mammography screening. They therefore ignored the data on all-cause mortality.

The rules for interpreting the results of randomised controlled clinical trials (RCTs) stipulate that for determining efficacy of intervention, comparisons of deaths must only be made between the entire group offered screening and the entire control group not offered screening. That is, reduction of deaths due to one cause should not be considered separately because this might ignore increased deaths due to other causes resulting from treatment. If the deaths from one cause goes down in the screened group compared to the control group, this is only a valid measure of efficacy if the deaths from all causes goes down by the same amount. That is, deaths from other causes have not gone up by the same amount as a result of harmful treatment following screening. (This requirement was highlighted by Black et al in “All-cause Mortality in Randomized Trials of Cancer Screening”. J Natl Cancer Inst, 6 Feb 2002; 94(3):167-73 and shown to be a methodological flaw in most screening trials).

The panel’s admission that they were ignoring all-cause mortality yet comparing the deaths of a part of the screened group (those with breast cancer) with the same unmatched part of the control group shows that they do not understand the rules for interpreting randomised controlled trials. This suggests that their other conclusions are likely to be invalid.

Despite this serious shortcoming, as I claimed in my Medical Hypotheses paper in 1996, the deaths from all causes were reported in most of the RCTs evaluating mammography screening. Overall deaths were not reduced by screening because the reduction in breast cancer deaths was accompanied by a comparable increase in deaths from other causes, including other cancers, in the screened group. This was presumably due to the harm from post-screening treatment such as radiotherapy that was used more among women in the screened group. This typically appeared as an increase in heart failure and, to a lesser extent, an increase in deaths from other cancers.

A second rule for running RCTs is that no other treatments can be used differently between the screened and control groups that could confound the results. This potential harm from radiotherapy was known at the time but ignored by all trial leaders. I notified one of the trial leaders at the time of this potential confounding factor and his response was that radiotherapy was not harmful. Much of the claimed benefit from screening is derived from the data from his Two Counties trial. Most trials did not even report on the use of chemotherapy in the two arms of the trial.

This lack of reduction in deaths from all causes was confirmed in 2009 by the Nordic Cochrane Group. They separated the seven RCTs into two groups: those with adequate randomisation and satisfactory operation, and those with inadequate randomisation or other methodological flaws. They found that in the 3 better designed and run trials there was no reduction in all-cause mortality after 13 years.

They also found that a significant reduction in breast cancer mortality (25%) was only observed in the 4 inadequately designed trials. In the 3 better quality trials the reduction in breast cancer deaths (10%) was not significant after 13 years and there was no reduction in all cancer deaths after 10 years. (One of the harms from radiotherapy is a weakened immune system that can increase the number of deaths from other cancers.)

They concluded that breast cancer mortality was not a reliable outcome because the misclassification of cause of death in these 4 poorer quality trials biased the results in favour of screening, confirming my original claim in 1996.

A third rule for running RCTs is that deaths caused by the post-screening treatment must be added to the number of deaths for the cancer the treatment was being given for. That is, added to deaths from breast cancer rather than deaths from other causes as was done in most trials. This is what the Nordic Cochrane Group referred to as “misclassifications of cause of death that was biased in favour of screening” because it appeared to reduce the number of breast cancer deaths in the screened group.

So unless the proponents of mammography screening can answer this issue, there is no evidence that screening saves any lives.