Recently, you probably saw the newspaper articles about “new fears” raised by tamoxifen, the drug used to prevent and treat breast cancer. The stories concerned a Dutch case control study published in The Lancet (19 February 1994), which showed that
This rather grim finding, which might seem straightforwardly damning to you or me, didn’t seem to worry either medical correspondents or the original researchers. The latter simply massaged the statistics and somehow concluded that the benefits of tamoxifen outweighed the risk of developing endometrial cancer. “Endometrial cancer has a more favourable prognosis than breast cancer, so no patient should be denied tamoxifen treatment of her breast tumour because of anticipated adverse effects on the endometrium,” concluded Dr Flora van Leeuwen, the Dutch epidemiologist in charge of the study.
The fuss mainly centred around the ethics of the new research programme, which is administering this drug to healthy women supposedly “at risk” of developing breast cancer. The Lancet study itself, in light of these new findings, believed this risk wasn’t justifiable; not surprisingly, Dr Jack Cuzick, chairman of the international trialists’ group, strenuously disagreed.
Once again, it seems, medical science is playing statistical sleight of hand, the same sort being played with hormone replacement therapy. Buried in the Letters page of the American Medical Association’s journal (8 December 1993) was the astonishing conclusion of a study by Brigham and Women’s Hospital which demonstrated that one quarter of women on HRT had an increased density of breast tissue ordinarily only seen via mammogram in young women, evidence of rapidly dividing cells. An accompanying letter by the US Centres for Disease Control and Prevention conceded that, yes, HRT probably promotes tumour growth among this 25 per cent of users. Nevertheless, the CDC did their arithmetic and concluded that since, statistically speaking, even women with breast cancer taking HRT have a survival advantage over those who don’t, most women would benefit from HRT. Their biggest concern seemed to be that HRT might complicate interpretation of a user’s mammogram.
These episodes provide a snapshot of everything that is wrong with modern medicine today. With all the considerable resources being poured into the so called war on breast cancer, medicine seems to overlook every obvious signpost about cause (the known role of hormones and dietary fat, the suspected role of pesticides see p 4) in favour of ever more arcane and dangerous means of detecting it and interfering with the biological processes that help it to thrive.
Someday, doctors may recover their ability to make the simple connection between giving people a drug that causes cancer and causing cancer cases to go up. For the moment, however, they are blinded by their own clever statistics