NCPA - National Center for Policy Analysis

Experts Do Not Agree On Efficacy Of Mammograms

September 5, 2002

The debate over the efficacy of breast cancer screening compared to the risks is far from settled. For example, two recent studies in Annals of Internal Medicine come to different conclusions on the benefits and risks of mammography.

A study by the United States Preventive Services Task Force makes recommendations that are generally followed by the nation's primary care doctors. It supports mammography every one to two years for women ages 40 to 74. However, a second study appearing in the same issue is more controversial:

  • A second study determined that women in their 40s reap no benefit from mammography and have real risks of harm from unnecessary treatment.
  • Earlier findings from the second study after seven years also found no benefit, but some medical experts predicted that benefits would emerge with time.
  • The new findings show that even 11 to 16 years after the women were enrolled, mammography had not saved any lives and had led to excess treatment.

The current dispute on the value of routine mammograms began last year when two researchers who examined the major clinical trials concluded that nearly all were so flawed as to be invalid. Women who had the test were just as likely to die from breast cancer as those not screened, they reported in The Lancet.

While cancer researchers recognize that not every cancer will grow and become deadly, they cannot predict which ones are dangerous and which are not, so they treat them all.

According to Harold Sox, editor of Annals of Internal Medicine, the big picture message is that the effect of screening in any age group is limited at best.

Sources: Gina Kolata, "New Mammogram Studies Divided on Benefits," New York Times, September 3, 2002; Anthony B. Miller, et al., "The Canadian National Breast Screening Study-1: Breast Cancer Mortality after 11 to 16 Years of Follow-up," Annals of Internal Medicine, September 3, 2002; and Linda L. Humphrey et al., "Breast Cancer Screening: A Summary of the Evidence for the U.S. Preventive Services Task," Annals of Internal Medicine, September 3, 2002.


Browse more articles on Health Issues