Breast screening benefits overstated - claim
Friday December 9th, 2011
Researchers today called for a rethink of how breast screening is done - claiming it can do more harm than good in its present form.
Analysts claim the stress undergone by women who are screened combined with the risk of wrongly being led to think they have cancer may outweigh the programme's success in detecting the disease.
Researchers at the University of Southampton, UK, found that the harm of screening largely offset the benefits up to 10 years, after which the benefits accumulate, but by much less than predicted when screening was first started.
Their findings, published in The British Medical Journal, updated the 1986 Forrest report, which led to the introduction of breast cancer screening in the UK.
The original report estimated the number of screened and unscreened women surviving each year over a 15-year period and suggested that screening would reduce the death rate from breast cancer by almost one third with little harm and at low cost.
But researchers re-examined the original report’s survival estimates by combining the benefits and harms of screening in one single measure and found that the inclusion of false positives and unnecessary surgery reduced the benefits of screening by about half.
The latest results are based on 100,000 women aged 50 and over surviving by year up to 20 years after entry to the screening programme.
The best estimates generated negative net QALYs – a combined measure of quantity and quality of life – for up to eight years after screening and minimal gains after 10 years.
After 20 years, net QALYs accumulate, but by much less than predicted by the Forrest report.
The authors call for improvements in the way that patients most likely to benefit from surgery are identified.
More research is also needed on the extent of unnecessary treatment and its impact on quality of life, while the meaning and implications of over-diagnosis and overtreatment need to be better, they add.
Uncertainty surrounding the extent of overtreatment came to the fore last month when a study of French women put over-diagnosis of invasive breast cancer due to screening at about one per cent.
But Catherine Priestley, a nurse specialist at Breast Cancer Care, said women should wait for the findings of an independent review of screening announced in October.
She warned of "confusion and anxiety" caused by a range of claims about screening.
Ms Priestley said: "We know that prompt detection of breast cancer can lead to more effective outcomes, so until it is possible to accurately determine the progression of cancers found through mammograms, screening remains an effective option for detecting breast cancer as soon as possible."
British Medical Journal December 9 2011
Tags: Cancer | Europe | UK News | Women’s Health & Gynaecology
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