The cumulative risk of a false-positive recall in the Norwegian Breast Cancer Screening Program

Biennial breast cancer screening for women ages 50-69 years is recommended by the World Health Organization. It has been claimed that the cumulative risk of a false-positive recall is a significant disadvantage in breast cancer screening programs. The primary objective of this study was to estimate the cumulative risk of a false-positive recall during a screening period of 20 years in women ages 50-51 years who are screened biennially in a population-based screening program. A secondary objective was to estimate the cumulative risk of undergoing fine-needle aspiration cytology, core needle biopsy, and open biopsy with benign morphology in the same group of women.

The Norwegian Breast Cancer Screening Program invites all women ages 50-69 years who reside in the country to a 2-view mammography biennially. A nationwide data base that covers all of the invited women includes individual information about all screening activity. Results from three screening rounds in four counties were the basis for this study. False-positive recalls due to abnormal mammograms among 83,416 women who participated all the 3 screening rounds were the basis for the estimations.

It was calculated that women ages 50-51 years who participate in biennial screening run a cumulative risk of 20.8% for a false-positive recall during a screening period of 2 decades. The cumulative risk of undergoing fine-needle aspiration cytology was estimated at 3.9%, and the risk of undergoing core needle biopsy or open biopsy with benign morphology was 1.5% and 0.9%, respectively.

False-positive recalls are a disadvantage in a breast cancer screening programs, but the cumulative risk seemed to be acceptable in the Norwegian Breast Cancer Screening Program. It is important to communicate the existence and extent of this risk to the target group.