Odds of False-Positive Mammograms During 10 Years of Screenings
The cumulative probabilities of false-positive mammography results were 60% and 40% for annual and biennial screening, respectively.
The U.S. Preventive Services Task Force recommends biennial screening mammography starting at age 50 unless a woman is at high risk for breast cancer (JW Womens Health Nov 16 2009). Despite this recommendation, many patients request, and many providers and societies continue to recommend, earlier and more frequent screening. In this study, researchers used data from a breast cancer surveillance consortium to model the cumulative probability of a false-positive screening mammogram under differing screening approaches. More than 160,000 women were included in the registry.
During 10 years, the adjusted cumulative probabilities of a false-positive mammography result were 61% for annual screening and 42% for biennial screening, regardless of whether a woman started screening at age 40 or 50. Although most false-positives resulted in additional imaging without biopsy, the cumulative probability of a false-positive biopsy recommendation was 7% for annual screening and 5% for biennial screening beginning at age 40 (and was slightly higher if screening started at age 50).
Comment: During 10 years, a majority of women who undergo annual screening mammograms will receive at least one false-positive mammography result. For women who undergo biennial screening, this rate is lower but remains relatively high at 40%. Because rates for both annual and biennial screening are high, that false-positive concerns would be a decisive factor for most women’s choice of annual versus biennial screening seems unlikely.
Jamaluddin Moloo, MD, MPH
Published in Journal Watch General Medicine November 10, 2011