BREAST cancer screening in Britain may be causing more harm than good, according to research.
Experts found that women may be likely to be harmed by the programme and undergo unnecessary surgery, especially in the first decade of being screened.
James Raftery, professor of health technology assessment at the University of Southampton, led the new study which examined data from the 1986 Forrest Report.
The Forrest Report, which led to the introduction of breast cancer screening in the UK, determined the benefits of screening in terms of quality adjusted life years or QALYs (a measure of quantity and quality of life).
It found about 3,000 QALYs in terms of lives saved over a 20-year period for every 100,000 women who were invited for screening.
But at the 10-year mark, the number of QALYs stood at only about 1,000.
In the new analysis, Prof Raftery and his colleague Maria Chorozoglou included estimates of the risk of women being harmed, which were not included in the Forrest Report.
Harms include false positives (abnormal results that turn out to be normal) and over-treatment (treatment or surgery on harmless cancers that would never have caused symptoms or death during a patient’s lifetime).
They found that once harms were included, the QALY benefits in terms of lives saved was only 1,500 QALYs after 20 years – half the figures quoted in Forrest. And, in the first few years of screening, women were, on average, more likely to be harmed than benefit.
Prof Raftery said: “At up to eight years, the harms generally outweigh the benefits but at 20 years there are greater positive benefits.
“Nevertheless, either way, the benefit to patients is less than was stated in Forrest.”
Prof Raftery said the vast majority of women undergoing surgery to remove a suspected cancer did not actually need the treatment.
“There are lots of women who have had surgery who believe their lives were saved when in fact only around one in 10 have had their life saved,” Prof Raftery said.
He continued: “It’s very tricky because if you are a woman invited for screening, the harms are up-front in the first few years while the benefits take a lot longer to kick in. It takes at least five years of screening before a life is saved.”
The latest study, published in the British Medical Journal (BMJ), follows previous research which found women undergoing NHS breast cancer screening are being “misinformed” and not told about the harms of over-diagnosis.
Writing in the Journal of the Royal Society of Medicine (JRSM) in August, researchers from the Nordic Cochrane Centre in Denmark said the risks of over-diagnosis had been downplayed.
They accused the heads of the NHS programme of sticking to beliefs from 25 years ago about the benefit of mammograms and supplying women with “astonishingly misleading” statistics on death rates. In 2009, experts from the same institution said one in three breast cancers detected by screening may be harmless.
Prof Raftery said: “Being screened for breast cancer can be an understandably difficult time for women and can cause anxiety and stress, not only for the patient, but for the family too.
“If we can ensure that women have a better understanding of the risks of unnecessary treatment before they are screened, it will be better for the patient.”