It’s nice to have clear-cut rules, especially about when to undergo anxiety-provoking tests like mammograms. So it’s understandable that women and doctors were upset by new recommendations from the U.S. Preventive Services Task Force. The guidelines went from something definite, mammography every year or two starting at age 40, to something more vague, that women in their 40s and those 75 and older should discuss the issue with their doctor.

The change seems like a setback for women, and it is disturbing to learn that mammography isn’t very effective for women in their 40s and may even do them more harm than good. It’s also discouraging that research has found that more testing does not necessarily benefit, and may even harm, consumers.

We can expect more discomforting recommendations in the future, as many medical practices come under stricter scientific examination. The aim of "evidence-based medicine" is to ensure that more of what doctors do for patients actually helps, and that our health-care decisions are based on fact rather than advertising, profit, or tradition.