Multi-gene panel analysis in BRCA1/2-negative patients suspected of hereditary breast and ovarian cancer syndrome: Real-world data from a single institution

Aim Although BRCA1/2 is most frequently associated with hereditary breast and ovarian cancer (HBOC), many other related genes have been implicated. Therefore, we investigated the prevalence of non-BRCA1/2 genes associated with hereditary cancer predisposition in BRCA1/2-negative patients from the Department of Genetic Medicine and Services with breast and ovarian cancer using a multi-gene panel (MGP) analysis. Methods We conducted a retrospective MGP analysis (National Cancer Center Onco-Panel for Familial Cancer; NOP_FC) in BRCA1/2-negative patients with breast, ovarian, and overlapping breast/ovarian cancers who visited our genetic counseling between April 2004 and October 2022. Results NOP_FC was performed in 128 of the 390 BRCA test-negative cases (117 breast cancer, 9 ovarian cancer, and 2 overlapping breast/ovarian cancer cases). Among the BRCA1/2-negative patients, nine (7.7%) with breast cancer and one (11%) with ovarian cancer had pathogenic variants (PVs) in non-BRCA1/2 genes associated with breast and ovarian cancers, respectively. Five patients had PVs in RAD51D, two in PALB2, one in BARD1, one in ATM, and one in RAD51C. Conclusions Additional MGP testing of germline genes associated with hereditary cancer predisposition syndrome in BRCA1/2-negative breast and ovarian cancer patients revealed PVs in non-BRCA1/2 breast cancer- and ovarian cancer-related genes in 7.7% of breast cancer and 11% of ovarian cancer. Therefore, additional testing may provide useful information for subsequent risk-reducing surgery and surveillance in BRCA1/2-negative patients.