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

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. 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. 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. 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.