Screening mammography every other year reduced false-positive recalls by about one-third compared to annual screening, but was associated with a small increase in the probability of late-stage cancer diagnosis, according to a study funded by the NCI and published in Annals of Internal Medicine. To compare the cumulative probability of false-positive results and stage of cancer diagnosis after 10 years of screening with either an annual or a biennial schedule, researchers analyzed data from 169,456 women who underwent first screening mammography at ages 40 to 59 and 4,492 women diagnosed with incident invasive breast.
“Cumulative probability of false-positive biopsy recommendation was 7.0% (CI, 6.1% to 7.8%) with annual and 4.8% (CI, 4.4% to 5.2%) with biennial screening,” the researchers reported. “A non–statistically significant increase in the proportion of late-stage cancers was observed with biennial compared with annual screening (absolute increases, 3.3 percentage points [CI, −1.1 to 7.8 percentage points] for women age 40 to 49 years and 2.3 percentage points [CI, −1.0 to 5.7 percentage points] for women age 50 to 59 years) among women with incident breast cancer.”
The researchers concluded that after 10 years of annual screening, more than half of women will have at least one false-positive recall, and 7% to 9% will have a false-positive biopsy recommendation. “Biennial screening appears to reduce the cumulative probability of false-positive results after 10 years but may be associated with a small absolute increase in the probability of late-stage cancer diagnosis,” they added. ■
Hubbard RA, et al: Ann Intern Med 155:481-492, 2011.