Breast cross-examination

A few weeks ago we published a report by Nancy Baxter and the Canadian Task Force on Preventive Health Care on the effectiveness of breast self-examination (BSE) and BSE instruction in reducing breast cancer mortality.1 The report showed that BSE can be credited with an increase in breast biopsies, but not with an increase in breast cancer survival, or even with the detection of tumours at an earlier stage. And so the Task Force has downgraded the routine teaching of BSE to a “D” recommendation: that is, there is “fair evidence” that we shouldn't bother.

To many women, and to many health professionals, this seemed a perverse and wasteful assault on common sense. One of the most potent beliefs about cancer is that a stitch in time saves nine. Early detection has been promoted with such zeal by the medical profession and by advocacy groups that it has become a notional proxy for “prevention” and even “cure.” The benefits of mammography screening programs are taken to be real, but some researchers, taking a harder look, have pronounced them a mirage.2 Now the available evidence is telling us that the benefits of BSE are, perhaps, the illusory product of wishful thinking.

Our conceptions of illness and illness management carry a heavy ideological payload. In the case of breast cancer, that ideology concerns empowerment: the empowerment of women to set the research agenda, to motivate prevention and influence care, to take control of their health. When Baxter's article was published, women insisted in the lay media that they, not their doctors, are finding breast cancers. “It's in your hands,” read the headline of one such testimony.3 But was the poor prognosis of this woman's metastatic cancer also in her hands? One could argue that the rhetoric of cancer puts an intolerable burden of responsibility and self- determination on the patient. Among the predictors of the outcome of breast cancer are such occult factors as gene mutations, cell-mediated immune responses, mitotic activity, rapidity of onset, growth rate, histology, anatomic stage, and so forth. The finding that 29% of women with stage 1A breast cancer already have micrometastases in their bone marrow4 should give pause to the champions of screening. The more we learn, the less we seem to know. The complexity of cancer is hardly a fair match for anyone, no matter how vigilant and well-informed she may be. We need to follow Baxter's example in being honest about the harms, and not merely the benefits, of cancer screening and management.

Cancer screening is not a field of dreams, but a minefield of surprises and broken promises. We have a long way to go. Let's proceed with less rhetoric and more candour. — CMAJ