False-positive mammograms in women aged 40-59 years cost an estimated $2.8 billion per year in the United States in 2012-2013, according to a report published April 6 in Health Affairs.

The cost of screen-detected invasive breast cancer overdiagnoses was $1.2 billion a year for that time period and age group. Invasive breast cancers represent about $1 billion of that, with the rest coming from overdiagnoses of ductal carcinoma in situ (DCIS), Mei-Sing Ong, Ph.D., and Dr. Kenneth D. Mandl, both of Boston Children’s Hospital, estimated.

Using expenditure data for 702,154 women from a major U.S. health care insurance plan, the investigators calculated that the average cost of a false-positive mammogram – the mammography plus all related costs over the next 12 months – was $852. The average 12-month costs for invasive breast cancer and DCIS were $51,837 and $12,369, they reported (Health Aff. 2015 Apr. 6 [doi:10.1377/hlthaff.2014.1087]).

Dr. Ong and Dr. Mandl used a false-positive rate of 11% for the mammogram estimate, although they also calculated costs based on a range of rates from 5% to 20%. Based on recent studies in the New England Journal of Medicine and the BMJ, they used an overdiagnosis rate of 22% for the breast cancer estimate; the overdiagnosis rate of 86% for DCIS came from a 2004 study.

“The disutility of overdiagnosis,” together with the high diagnostic and treatment costs of mammography, “may tilt the balance to the point where screening [based on age] appears relatively cost ineffective,” Dr. Ong and Dr. Mandl wrote. It may be time to “shape a more individualized approach to determining who should receive screening, focusing on women who are most likely to benefit.”

Dr. Ong is supported by a fellowship from the National Health and Medical Research Council in Australia, which played no role in the study. Dr. Mandl did not report any conflicts.