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New study supports claim that breast screening is harmful

12 December, 2011

A new study published recently on supports the claim that the introduction of breast cancer screening in the UK may have caused more harm than good.

Harms included false positives (abnormal results that turn out to be normal) and overtreatment (treatment of harmless cancers that would never have caused symptoms or death during a patient’s lifetime). This may be because the cancer grows so slowly that the patient dies of other causes before it produces symptoms, or the cancer remains dormant or regresses.

It shows that the harms 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.

The Forrest report in 1986, which led to the introduction of breast cancer screening in the UK, estimated the number of screened and unscreened women surviving each year over a 15-year period.  Costs and benefits were measured in quality adjusted life years or QALYs (a combined measure of quantity and quality of life) but it omitted harms.

It suggested that screening would reduce the death rate from breast cancer by almost one third with few harms and at low cost.

Since the Forrest report, the harms of breast cancer screening have been acknowledged. So, researchers at the University of Southampton 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 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 by the Forrest report.

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. From a public perspective, the meaning and implications of overdiagnosis and overtreatment need to be much better explained and communicated to any woman considering screening, they add.

However, the continuing uncertainty surrounding the extent of overtreatment is apparent in a study of French women published on last month, which put overdiagnosis of invasive breast cancer due to screening at around 1%.

Source: BMJ

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Elizabeth | Sunday, May 27, 2012, 11:01 PM
The Nordic Cochrane Institute have changed their conclusion on breast screening, no to little benefit, with significant over-diagnosis...with 50% of screen detected cancers amounting to over-diagnosis. I disregard everything coming from Papscreen and Breast Screen and go straight to the NCI and other overseas sources. I'll never understand how it is acceptable to mislead and harm women to maximize coverage with no regard for the legal right of informed consent. In my opinion, it is paternalistic and unethical and perhaps, even more... The most concerning thing, we spend millions on breast screening and vested and political interests may keep this program in place for many years to come...women should be given the NCI summary on the Risks and Benefits of Mammograms and the program should be scaled back to accommodate those women who still choose to screen. Our cervical screening program is a disgrace and should be the subject of an independent enquiry, women are being seriously over-screened and over-treated and some are left with issues as a result...there was never a need to harm so many, to help so there is absolutely no excuse, we can now identify the roughly 5% of women who are HPV positive at age 30 and only those women should be offered a 5 yearly pap test. Those negative can test another 4 times at ages 35,40,50 and 60. This greatly reduces pap testing, false positives, over-treatment and is more likely to prevent these rare cancers. This is the new Dutch program, 5 hrHPV primary triage tests - their women are also using the Delphi Screener, the reliable self-test HPV device. Our program IMO, serves vested interests who make a fortune from over-screening and over-treatment, our program is not in the interests of women, it's harmful.