News from the US, I can scarcely believe it: The New York Times reports that the American Cancer Society now accepts that screening for breast and prostate cancer is not only inefficient, but frequently inaccurate and alarmist. It has realised that such programmes – designed to detect cancer early – can do damage too, because they often detect cancers or pseudocancers that were never going to maim or kill.

That is the bit I can believe. After all, these are evidence-based observations, and none is particularly new. A recent paper in the Journal of the American Medical Association (Jama) also highlighted the weaknesses of screening. What I have difficulty with is that paper’s conclusion: “To reduce morbidity and mortality from prostate cancer and breast cancer, new approaches for screening, early detection, and prevention for both diseases should be considered.” The problem with screening and even early detection is that because these two elements sound useful, we have great difficulty in believing it when the evidence tells us they are not.

The Jama paper states that, after 25 years of screening, “conclusions are troubling: Overall cancer rates are higher, many more patients are being treated, and the absolute incidence of aggressive or later-stage disease has not been significantly decreased”. The authors also say that screening comes at significant cost, including overdiagnosis and overtreatment. The complications of therapy are likely to get worse as the population ages. Not only that, but treatments for relatively indolent disease may in themselves do harm.

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