1.3 million misdiagnosed breast cancer in US

WASHINGTON - Agence France-Presse

Because of routine mammograms, more than a million US women have received unnecessary treatment. REUTERS photo

More than a million American women have received unnecessary and invasive cancer treatments over the last 30 years, thanks to routine mammograms that detected harmless tumors, scientists said Nov. 22.

The results throw new doubt over the effectiveness of an already controversial cancer screening tool that is aimed at detecting tumors before they spread. To reach the one million figure, researchers compared the number of breast cancer cases detected at early and late stages among women over 40 between 1976 and 2008.

Their analysis showed that, since mammograms became standard in the U.S., the number of early-stage breast cancers detected has doubled in recent years, doctors found tumors in 234 women out of 100,000. But in that same period, the rate of women diagnosed with late-stage breast cancer has dropped just eight percent from 102 to 94 cases out of 100,000.

“We estimated that breast cancer was overdiagnosed, i.e., tumors were detected on screening that would never have led to clinical symptoms in 1.3 million U.S. women in the past 30 years,” authors Gilbert Welch and Archie Bleyer wrote in a study.