Breast cancer screening implications of risk modeling among female relatives of ATM and CHEK2 carriers

Abstract

Background: With the increasing use of multigene panel tests, pathogenic and likely pathogenic (P/LP) variants are identified more frequently in the moderate-penetrance breast cancer genes ATM and CHEK2. Lifetime breast cancer risk among women with P/LP variants in these genes generally exceeds 20%, meeting the threshold at which high-risk breast cancer screening through breast magnetic resonance imaging (MRI) is recommended. Methods: Among a registry-based sample of 56 ATM and 69 CHEK2 carriers, the authors sought to determine the percentage of relatives in whom a P/LP variant would impact breast cancer surveillance. Lifetime breast cancer risks for unaffected, female first-degree and second-degree relatives were estimated using the Breast and Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm (BOADICEA). Results: Among first-degree relatives of ATM and CHEK2 carriers, only 22.6% and 14.9%, respectively, were found to have lifetime breast cancer risks of ≥20% based on family cancer history alone; however, when including the proband's P/LP variant in the model, these percentages increased significantly to 56.6% and 55.3%, respectively (P