Mammograms' benefits may not outweigh risks for all women

New research on mammography suggests for women of certain ages, the benefits of this routine test don't actually outweigh the risks. The comprehensive analysis of 50 years of breast cancer research was published on April 1 in the Journal of the American Medical Association by researchers at Harvard Medical School's Department of Health Care Policy and Brigham and Women's Hospital in Boston.

Dr. Nancy Keating, co-author of the report, who is an associate professor of Health Care Policy at Harvard Medical School, says their analysis indicates mammography guidelines should be based on each individual patient's complete health profile, such as family and medical history, genetic risk factors and overall life expectancy.

"Mammography does have some benefit in the likelihood of dying from breast cancer, but these benefits are relatively modest," Keating told CBS News. "Particularly for women who are at very low risk of breast cancer -- the benefits are quite small."

In their analysis the authors found mammography reduces breast cancer mortality rates overall by about 19 percent. For women in their 40s, regular screening with mammography only lowered breast cancer-related deaths by around 15 percent. Post-menopausal women were found to benefit the most from annual mammography; the screening test lowered death rates of women in their 60s by 32 percent.

Overall American women have a 12.3 percent lifetime risk for developing the breast cancer. Approximately 40,000 women will die from the disease this year, according to the American Cancer Society.

Mammography is currently the most commonly-used screening test for breast cancer but it's not always accurate. Statistically, mammography misses about 20 percent of breast cancer malignancies, according to the National Cancer Institute. On the other hand, the test can also lead to false positive results, over-diagnosis and even unnecessary treatment.

By the authors' calculations, more than half of the women who have routine mammography over a period of 10 years can expect a false positive diagnosis, and 20 percent of these false positives will lead to unnecessary biopsies.

This paper comes out on the heels of another controversial study published in February by the British Medical Journal, which tracked 90,000 women who had routine mammograms over a period of 25 years. That study also found regular mammograms didn't necessarily lower risk for breast cancer death, even for women in their 50s, when the risk for developing the disease typically starts to increase.

In recent years, mammography screening guidelines have come under fire, due in part to the U.S. Preventive Services Task Force's decision in 2009 to revise their mammography screening guidelines and recommend women seek out the test starting at age 50 rather than 40. The USPSTF's recommendations run contrary to the American Cancer Society, which suggests women begin routine screening at age 40.

The USPSTF -- an independent panel of national preventive medical experts that advises government health agencies -- updates their screening guidelines every five years. This year the panel expects to revisit their current mammography guidelines and determine if any new research indicates a need for revisions.