By ecancer reporter Janet Fricker

Women who experience a false-positive mammography screening result have a two-fold increased risk of breast cancer in later life, finds a study in British Journal of Cancer.

The investigators, led by Marta Román from Hospital del Mar Medical Research Institute, Barcelona, found that after a second false-positive screening result risk increased to four-fold.

For the study, a joint analysis was undertaken using data from three population-based screening programs targeting women aged 50 to 69 years run according to the European Guidelines for Quality Assurance in Breast Cancer Screening.

Data for the study, which included 1,149, 467 women undergoing 3,510,450 screening examinations, was obtained from the Copenhagen Mammography Register in Denmark, Breast Screen Norway and the Spanish Breast Cancer Screening Program.

A false-positive screening result was defined as a recall for further assessment without confirmation of cancer diagnosis regardless of the procedures involved; and a screen-detected cancer as a breast cancer diagnosed at further assessment due to abnormal findings of screening mammography interpretation.

An interval breast cancer was defined as a breast cancer diagnosed after negative screening or after false-positive screening either before the next screening (2 years) or within 2 years after the final screening for women who have reached the upper age group.

Results found compared to women with negative tests, those with false-positive results had a two-fold risk of screen detected (HR=2.04, 95% CI: 1.93-2.16) and interval cancer (HR=2.18; 95% CI: 2.02-2.34).

Furthermore, women with a second false-positive result had over a four-fold risk of screen-detected and interval cancer (HR=4.71, 95% CI: 3.81-5.83 and HR=4.22, 95% CI: 3.27-5.46 respectively).

Interestingly, the investigators found between 40 and 45% of breast cancer cases in the contralateral breast to the prior benign breast lesion.

Such findings, write the authors, suggest lesions are markers of future breast cancer risk rather than pre-malignant lesions that will develop into breast cancer.

“Based on our findings it might be advisable to inform women with false-positive results about their specific increased risk for screen-detected and interval breast cancer.

“The highly increased risk reveals a sub-group of women that may be eligible for more intensive screening strategies,” write the authors.

Since false-positive results affect a large number of screened women, they add, the outcome of previous screening results should be incorporated into risk prediction models.

Reference: Román M, Hofvind S, vonEuler-Chelpin M, et al. Long-term risk of screen-detected and interval breast cancer after false-positive results at mammography screening: joint analysis of three national cohorts. BJC : https://doi.org/10.1038/s41416-018-0358-5 (Published 19 December)