Implication and Influence of Multigene Panel Testing with Genetic Counseling in Korean Patients with BRCA1/2 Mutation–Negative Breast Cancer

PURPOSE: The aim of the study was to evaluate the clinical implication of multigene panel testing of beyond BRCA genes in Korean patients with BRCA1/2 mutation-negative breast cancer. MATERIALS AND METHODS: Between 2016 and 2019, a total of 700 BRCA1/2 mutation-negative breast cancer patients received comprehensive multigene panel testing and genetic counseling. Among them, 347 patients completed a questionnaire about cancer worry, genetic knowledge, and preference for the method of genetic tests during pre- and post-genetic test counseling. The frequency of pathogenic and likely pathogenic variants (PV/LPV) were analyzed. RESULTS: At least one PV/LPV of 26 genes was found in 76 out of 700 patients (10.9 %). The rate for PV/LPV was 3.4% for high-risk genes (17 PALB2, 6 TP53, and 1 PTEN). PV/LPVs of clinical actionable genes for breast cancer management, high-risk genes and other moderate-risk genes such as ATM, BARD1, BRIP, CHEK2, NF1, and RAD51D, were observed in 7.4%. Patients who completed the questionnaire showed decreased concerns about the risk of additional cancer development (average score, 4.21 to 3.94; p < 0.001), influence on mood (3.27 to 3.13; p < 0.001), influence on daily functioning (3.03 to 2.94; p=0.006); and increased knowledge about hereditary cancer syndrome (66.9 to 68.8; p=0.025) in post-test genetic counseling. High cancer worry scales (CWSs) were associated with age ≤ 40 years and the identification of PV/LPV. Low CWSs were related to the satisfaction of the counselee. CONCLUSION: Comprehensive multigene panel test with genetic counseling is clinically applicable. It should be based on interpretable genetic information, consideration of potential psychological consequences, and proper preventive strategies.