A paper published in the current issue of the British Medical Journal is yet another inconvenient truth that demands a complete and unbiased re-evaluation of our national breast screening programme (NHSBSP). The paper, based on the World Health Organisation (WHO) database, set out to demonstrate that the introduction of screening by mammography in some countries in Europe was associated with a steeper fall in mortality from breast cancer than in neighbouring countries that had delayed offering this service.
To their surprise they discovered that paired neighbouring countries had experienced the same and very welcome fall in breast cancer mortality whether or not screening had been introduced. Furthermore the steepest fall in mortality observed was among the women under 50 who had not been invited for screening in all of the countries taking part in their study. They concluded that the recent downward trend in breast cancer mortality was nothing to do with screening but all thanks to improvements in treatment and service provision.
In 1987 Margaret Thatcher’s government published the Forrest report that advocated the establishment of a screening programme for breast cancer. Although the report had languished on the prime minister’s in-tray for six months, it was unveiled two weeks before a general election. Sir Patrick Forrest’s report was in good faith and based on the best evidence then available. At that time, as professor of surgery at Kings College Hospital, I was tasked with implementing the programme for the south-east of England and was invited to join the NHSBSP governing committee; I resigned about 10 years later.
U-turns do not embarrass clinical scientists, unlike politicians: if the evidence changes then our minds must change. As the national programme began to run its course, two disturbing observations made me begin to question my original support. First, about 10 years after the initiation of the service, updated analyses of the original data set by independent groups in Europe and the US found that the initial estimate of benefit in the reduction of breast cancer mortality was grossly exaggerated.