Do yearly mammograms reduce the number of breast cancer deaths? A new study casts doubt on their effectiveness

The debate over the necessity of annual mammograms continues as a recent study suggests that the screenings for breast cancer do not reduce the number of deaths from breast cancer.

Twenty-two percent of the women tested over a 25-year period who were diagnosed with invasive breast cancers were over-diagnosed, according to the British Medical Journal report released in February. The study followed almost 90,000 women from the ages of 40 to 59 who lived in Canada-half received annual mammograms and the others received a single physical exam.

The death rates from breast cancer were similar in both groups. Of the women who did not receive mammograms, 3,133 were diagnosed with breast cancer and 505 died of breast cancer. Of the women who had mammograms, 3,250 were diagnosed with breast cancer and 500 died of the disease. The study concluded that both groups had similar death rates, and 1 in 424 women who received mammograms also received unnecessary treatment including surgery, chemotherapy, and radiation.

“Our data shows that annual mammography does not result in a reduction in breast cancer specific mortality for women aged 40-59 beyond that of physical examination alone or usual care in the community. The data suggests that the value of mammography screening should be reassessed,” the authors of the study said.

The controversy over mammograms started in 2009, when the U.S. Preventive Services Task Force lowered its breast cancer screening recommendations to women ages 40 to 49 and suggested that women have a conversation with their doctors to see if a mammogram is necessary. The task force also suggested that women ages 50 to 74 receive mammograms every two years. The American Cancer Society and the American College of Radiology continue to recommend annual screenings for women over the age of 40.

According to The New York Times, 37 million mammograms are performed every year at the average cost of $100 each.