A new study in the British Medical Journal supports the claim that the introduction of breast cancer screening in the UK may have caused more harm than good.
Researchers say the harms included false positives and overtreatment (treatment of harmless - or slow growing - cancers that would never have caused symptoms or death during the woman's lifetime). The study shows that the harms of screening largely offset the benefits up to 10 years, after which the benefits do begin to accumulate, but by much less than predicted when screening was first started.
Breast cancer screening began in the UK in 1986, with experts predicting it would reduce the death rate from breast cancer by almost one third with few harms and at low cost.
Since then, the harms of breast cancer screening have been acknowledged. So, researchers at the University of Southampton (UK) set out to update the report's survival estimates by combining the benefits and harms of screening in one single measure. The results are based on 100,000 women aged 50 and over surviving by year up to 20 years after entry to the screening programme.
Inclusion of false positives and unnecessary surgery reduced the benefits of screening by about half. The best estimates generated negative net quality-of-life-scores (QALYs) 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.
The authors say more research is needed on the extent of unnecessary treatment and its impact on quality of life. They also call for improved ways of identifying those most likely to benefit from surgery and for measuring the levels and duration of the harms from surgery.
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Source: British Medical Journal