Mammograms Only Occasionally Save Lives, Analysis Finds

By Anne Harding

TUESDAY, October 25, 2011 ( — Some doctors and public-health experts have stirred controversy in recent years by arguing that aggressive breast-cancer screening does more harm than good. Many health professionals disagree, but perhaps the most compelling critics of the less-is-more philosophy are the many breast cancer survivors who claim that a routine mammogram saved their lives.

These survivor anecdotes—which often turn up in the media—may be causing the public to overestimate the true value of mammograms, a new study suggests. In an analysis published this week in the Archives of Internal Medicine, researchers at Dartmouth estimate that only about 1 in 8 women whose breast cancer was identified during a routine mammogram actually owe their lives to the screening.

This estimate doesn’t mean that women shouldn’t bother to get mammograms, but it does suggest that overly frequent screening can result in overtreatment, the authors say. Many tumors identified during routine mammograms would have grown very slowly (if at all) and would never have threatened a woman’s life, says H. Gilbert Welch, MD, one of the coauthors of the analysis.

“A certain fraction of women are being treated for a disease that was never going to bother them,” says Dr. Welch, a professor of medicine at the Dartmouth Institute for Health Policy and Clinical Practice, in Hanover, N.H.

The U.S. Preventive Services Task Force (USPSTF), a government advisory panel that issues guidelines on cancer screening, recommends that women start having mammograms every other year when they turn 50, while women who have risk factors for breast cancer should talk with their doctor about starting screening earlier. (Prior to 2009, the panel recommended annual mammograms for all women beginning at age 40.) A large study published last week found that biennial screening resulted in fewer false alarms and unnecessary biopsies than annual screening.

The results of the new analysis should reassure women with average breast-cancer risk that it’s safe to wait until age 50—or later—to begin mammograms, Dr. Welch says. However, he adds, women who would prefer to undergo screening earlier or more frequently should do so if it will make them more comfortable. “It’s generally a really close call, and how patients feel really matters,” he says.

Next page: Women should understand “trade-offs” of screening

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