Key clinical point: All patients with breast cancer who develop a second primary cancer should undergo multigene panel testing, according to researchers.
Major finding: Mutation rates in BRCA1/2-negative breast cancer patients with multiple primary cancers were approximately 7% to 9%, compared with about 4% to 5% in BRCA1/2-negative patients with a single breast cancer.
Study details: A comparison of mutation rates in 1,000 high-risk breast cancer patients (551 with multiple primary cancers and 449 with a single breast cancer) and 1,804 familial breast cancer patients (340 with multiple primaries and 1,464 with a single breast cancer).
Disclosures: This research was supported by grants from government agencies and foundations as well as the University of Pennsylvania. Some authors disclosed relationships with a range of companies.
Maxwell KN et al. JCO Precis Oncol. 2020. doi: 10.1200/PO.19.00301.