Yearly mammography screenings for women ages 40 to 59 do not reduce breast cancer deaths, even though they make a diagnosis of illness more likely, according to a long-term study of nearly 90,000 Canadian women.
The research, published Tuesday in the British Medical Journal, is the latest in a series of studies that question the value of annual breast X-rays for pre-menopausal women and whether too many women are being "overdiagnosed" by the popular test.
"We found absolutely no benefit in terms of reduction of deaths from the use of mammography," said study leader Dr. Anthony Miller, an epidemiologist at the University of Toronto's Dalla Lana School of Public Health.
The controversial finding is unlikely to trigger an immediate change in national screening policies, although it will enliven an already heated debate over screening. Experts have been arguing the merits of breast X-rays since 2009, when a government panel recommended that most women under 50 could safely skip the test. The U.S. Preventive Services Task Force determined that the chances that a 40-year-old woman would be diagnosed with invasive breast cancer in the next 10 years was 1.44% and that her odds of dying from it were just 0.19%.