1 in 5 women who have mammograms every 2 years will have to undergo follow up evaluation for a false positive finding

A new long-term study finds over 20 years, only one in five women who have mammograms every two years will have to undergo follow up evaluation for a false positive finding. Only one in 16 will have an unnecessary invasive procedure over two decades.

The study, published August 23, 2004 in the online edition of CANCER, a peer-reviewed journal of the American Cancer Society, should reassure physicians and patients that the risks of breast cancer screening are minimal given the notable benefit of breast cancer screening. The abstract of this article will be freely accessible via the CANCER Newsroom.

Breast cancer screening by regular screening mammography has a proven benefit to saving lives. However, false positives and subsequent recall for follow up evaluation create significant psychosocial distress.

The extent of false positive recall is unclear. Previous studies have claimed the cumulative risk of a high false positive recall over the years was significant. However, the estimates and conclusions made to date are weakened by flawed study designs.

Solveig Hofvind, M.Sc., and her colleagues from the Cancer Registry of Norway reviewed data of 83,416 women from the Norwegian Breast Cancer Screening program, a uniform national program providing biennial screening mammography for women who are 50 to 69 years of age.

The authors found that women who begin biennial screening mammography at age 50 or 51 and participate in screening for 20 years had a cumulative 20-year risk for false positive recall of 20.8 percent. The risk for undergoing invasive procedures with benign findings was considerably lower at 6.2 percent. Most of those were for fine needle aspiration (3.9 percent). Only about one in 66 women had a core biopsy with benign findings (1.5 percent). Fewer than one in a hundred women had open biopsy with benign findings (0.9 percent).

Given this low 20-year risk level, conclude the authors, "all the estimates seem to be quite acceptable and ought to be communicated to the target group."