Physicians should no longer routinely teach women aged 40-69 breast self examination as a screening technique for cancer because it can do more harm than good, the Canadian Task Force on Preventive Health Care has announced. The task force counsels healthcare providers on effective screening methods.
In a systematic analysis of 34 years of published studies of breast self examination, the Canadian task force concluded that there was evidence that the technique had no benefits and good evidence that harm is done (Canadian Medical Association Journal 2001;164:1837-46).
Dr Nancy Baxter, the lead author, who at the time of writing was a resident in general surgery at the University of Toronto, said that despite the fact that the technique had been promoted for 30 years, only about a third of women practised it monthly, while even fewer did it properly. Harm could be caused by anxiety and by unnecessary biopsies.
The Canadian task force's recommendations have produced confusion and anger among Canadian women and some disagreement among doctors.
Dr Cornelia Baines, professor of public health sciences at the University of Toronto, claimed that the task force was selective in its evidence and that “they have interpreted it in a misleading and incomplete way.” She said both mammography and breast self examination were necessary.
Karen DeKoning, president of the Canadian Breast Cancer Network (a network of organisations and individuals affected by breast cancer) said that it was wrong to tell women that self examination could harm them, and she urged them to continue the practice.
But Dr Steven Narod, director of preventive oncology at the University of Toronto, said it might be time to admit that the evidence for the usefulness of self examination was just not there.
The task force searched the electronic databases Medline, PreMedline, CINAHL, Health STAR, Current Contents, and the Cochrane Library for abstracts and full reports of studies published from 1966 to October 2000, which evaluated the effectiveness of breast self examination in reducing mortality from breast cancer.
The analysis was based on two randomised controlled trials in China and Russia; a non-randomised controlled trial in the United Kingdom; three case-control studies, one of which was part of the Canadian national breast screening study; and two cohort studies.
For women younger than 40, there was little evidence for effectiveness of breast self examination, the task force said. And because cancer incidence in this group was low, “the risk of net harm” from its use was even more likely. For women aged over 70, although the incidence of breast cancer was high, there was insufficient evidence to make a recommendation.
The article is accessible at www.cma.ca/cmaj
FRANçOISE SAUZE/SPL