What Doctors Don’t Tell You. Lynne McTaggart

is ‘intellectually dishonest’.³⁴

      After the publication of a Swedish meta-analysis some years ago, which pooled results from five studies conducted over five to 13 years on some 300,000 women, most members of the medical establishment have adopted as gospel its results: that for women 50 and over, regular screening can reduce breast cancer mortality by 30 per cent.³⁵ It is also generally agreed that no studies have shown a benefit for women younger than 50.³⁶ In the UK, the government offers mammography to women aged 50–64, and invites them to participate every three years.

      This ‘30-per-cent risk reduction’ has been adopted as a mantra by the medical profession. It has provided a justification of sorts to screen many groups, such as women under 50, where benefits of screening have never been shown. Despite all medical evidence to the contrary, the American Cancer Society and the American College of Radiology have carried on urging all women over 40 – which of course includes this limbo group between the ages of 40 and 49 – to have annual mammograms.³⁷

      But even among the over-fifties, there is no conclusive evidence that mammographic screening is doing any good. In the much-quoted Swedish study, the researchers came up with their figure by pooling all the results of three bands of age groups – the 40–49-year-olds, 50–69-year-olds and 70–74-year-olds – into an overview. The study showed a positive benefit (29 per cent reduction in mortality) among the women in their fifties, but none among the women in their forties or those in their seventies.

      However, when you actually examine the science behind these statistics, this is the only study to show clear benefit, even among the 50-year-olds. The 30 per cent improved survival figure being bandied about derives from several articles which examined all the studies of screening and attempted to pool the results. Although most studies didn’t show a clear benefit, the article concluded that those that were most scientific, or ‘randomized’ (that is, women assigned randomly to either screening groups or controls) all proved to be of benefit.³⁸

      However, Dublin’s Dr McCormick and his late colleague Petr Skrabanek, both scourges of unproven medical practice, have pointed out that three of the four of those trials considered most scientific ‘failed to reach statistically significant benefit for women aged 50 and over’.³⁹ These included two studies of an aggregate of 80,000 women, which were dismissed as ‘too small’ by one set of screening proponents.⁴⁰ In other words, to reach their favourable statistics, academics have combined entirely different types of scientific studies – those that set out with several groups of women to see what happens to them over time, versus analysing what has already happened to several groups of women – in an attempt to make the insignificant advantages of screening appear significant. In fact, two of the best breast cancer centres in the UK failed to lower deaths significantly using annual clinical exams and every-other-year mammograms.⁴¹

      It’s also wise to keep in mind what this 30 per cent supposed reduction in mortality actually translates into. At best, it may prevent or postpone one cancer death for between 7,000 and 63,000 women invited for screening every year.⁴²

      More recently, researchers from the University of British Columbia in Vancouver studied all the trials since the early ones that claimed a 30 per cent reduction in deaths from breast cancer in women over 50. There has been far less publicity, the Canadian researchers point out, about all the studies that have been done since those early days, showing that mammography does no good for anyone in any age group, but does great harm through false-positives and get-in-there-early intervention. They attacked mammography and indeed recommended that they be junked altogether after discovering that only one in 14 women with a positive mammogram result indicating breast cancer will actually have the condition.

      ‘Since the benefit achieved is marginal, the harm caused is substantial, and the costs incurred are enormous, we suggest that public funding for breast cancer screening in any age group is not justifiable,’ these epidemiologists concluded.⁴³

      In another Canadian study, when six trials of breast cancer screening were analysed, only one in 14 women with a positive mammography result indicating breast cancer actually had the condition. As with cervical cancer, this means that many women are going through needless worry and treatment on the basis of an inaccurate test.⁴⁴

      The latest evidence concurs that regular mammograms offers no survival advantage among any age group under 60.⁴⁵ In 2002, after studying all the most recent science, a committee of US cancer experts called the The Physician Data Query board (PDQ) concluded there is insufficient evidence to show that mammograms actually prevent deaths.⁴⁶ More than one-third of mammograms give false readings overall, two-thirds false-positives,⁴⁷ and the test is accurate less than half the time and only in the second half of a woman’s menstrual cycle.⁴⁸

      The rationale for screening has always been that the earlier you catch it, the smaller the tumour will be, and hence the greater your chances of beating the disease. However, this rationale doesn’t take into account that cancer doesn’t always metastasize at the same rate. Breast cancer isn’t a tidy disease that progresses in the same way for every woman; sometimes it spreads throughout the body, other times it advances in the breast alone. Much of our treatment doesn’t influence the outcome in any case.⁴⁹

      One reason may be that mammograms actually increase mortality rates. Among the under-fifties, more women die from breast cancer among screened groups than among those not given mammograms. The Canadian National Breast Cancer Screening Trial (NBSS), published in 1993, which screened 50,000 women between the ages of 40 and 49, showed that more tumours were detected in the screened group, but not only were no lives saved, but a third more women died from breast cancer in the group first offered screening.⁵⁰ Similar results occurred in three Swedish studies⁵¹ and also in those conducted in New York.⁵² One of the Swedish studies, conducted in Malmo, showed nearly a third more cases of breast cancer in women under 55 given mammograms over 10 years.⁵³ Even when you adjust results and allow that cancers among women aged 51–69 – the so-called ‘high-risk group’ – have been detected, screened women have nearly a 2 per cent higher incidence of breast cancer than controls.⁵⁴

      That more younger screened women die may reflect the fact that mammography is indiscriminant, picking up many cancers which would do no harm if left alone. The scattergun nature of the technology has several implications. This ability to pick up any sort of tumour falsely increases the incidence of breast cancer by a quarter to a half.⁵⁵ Adding all these benign tumours, which of course don’t lead to death, into the cancer data also has the effect of making it look like more people in the screened population survive because of early detection.

      By picking up all and several tumours of every variety, mammograms also could be falsely inflating the incidence of breast cancer by as much as one half.⁵⁶

      The third effect of regular mammograms is that