The impact of false positive breast cancer screening mammograms on screening retention: A retrospective population cohort study in Alberta, Canada.

Abstract

The impact of false positives on breast cancer screening retention is inconsistent across international studies. We investigate factors associated with screening retention, including false positive screening results, invasiveness of diagnostic procedures, and geographic variation in Alberta, Canada. A total of 213 867 women aged 50-67 years who had an index screen mammogram between July 2006 and June 2008 were evaluated at 30 months post index screen to determine the screening retention rate. The association of screening retention with invasiveness of the diagnostic procedure, time to diagnostic resolution, and region of residence were investigated using multivariable log binomial regression, adjusting for women's age. Women with false positive screening results were less likely to return for their next recommended screening than those with a true negative result (62.0% vs. 68.7%). Compared to women with normal screening results, the adjusted risk ratios of fail-to-rescreen for women with imaging-only follow-up, needle sampling, and open biopsy were 1.08 (95% CI: 1.05-1.12), 1.72 (95% CI: 1.44-2.07) and 2.29 (95% CI: 2.09-2.50) respectively. Screening retention rates were slightly higher for rural residents than urban residents. Time to diagnostic resolution was not associated with screening retention. Screening retention peaked at one year from the index date of the previous screening. Higher awareness of the strong negative impact that biopsies in the case of a false positive screening have on screening retention is needed. Such awareness can inform intervention strategies to mitigate the impact and improve screening retention rate.