After undergoing 10 years of annual mammography screening, more than half of women will receive at least one false-positive recall and 7% to 9% will receive a false-positive biopsy recommendation, results of a recent analysis indicate (Ann Intern Med. 2011;155:481-492).

The study looked at data from 169,456 U.S. women who had their first screening mammograms at age 40 to 59 years, between 1994 and 2006; and 4,492 women diagnosed with invasive breast cancer between 1996 and 2006. Over 10 years, 61.3% of women who started annual screening mammography at age 40 years could expect to be called back for additional normal imaging, compared with 41.6% of women who began biennial screening at age 40 years. In addition, 7% of women in the annual-screening group could expect to be advised to get a breast biopsy that would not ultimately lead to a diagnosis of breast cancer, compared with 4.8% of women screened biennially. Estimates were similar when screening began at age 50 years.

Although these results support the recommendation that biennial mammography will reduce a woman’s probability of obtaining a false-positive reading, the two-year screening interval appeared to be associated with a small absolute increase in the probability of late-stage cancer diagnosis.

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Adding to the screening-mammography controversy is another recent finding indicating that the probability a woman with screen-detected breast cancer has avoided a breast cancer death because of screening mammography is now likely to be well below 10%.

“Most women with screen-detected breast cancer have not had their life saved by screening,” concluded H. Gilbert Welch, MD, MPH, and Brittney A. Frankel in Archives of Internal Medicine. “They are instead either diagnosed early (with no effect on their mortality) or overdiagnosed.”