Abstract
BRCA1/2 genes are the most frequently germline mutated DNA-repair genes, and the survival of BRCA1/2 carriers has been extensively explored in breast cancer. However, the prevalence of germline mutations in non-BRCA1/2 DNA-repair genes and the survival of carriers are largely unknown in a large cohort of unselected breast cancer patients. Germline mutations in 16 DNA-repair genes were determined using a multigene panel in 7657 BRCA1/2-negative breast cancer patients who were unselected for family history of cancer or age at diagnosis. Among the 7657 BRCA1/2-negative breast cancer patients, 257 (3.4%) carried at least 1 pathogenic germline mutation in the 16 DNA-repair genes. The prevalence of DNA-repair gene mutations was significantly higher in familial breast cancers (5.2%, P = 0.002) and early-onset breast cancers (diagnosed at and before the age of 40) (4.5%, P = 0.003) than that of sporadic breast cancers (2.9%) (diagnosed above age of 40), respectively. The DNA-repair gene mutation carriers were significantly more likely to have a larger tumor (P = 0.04) and axillary lymph node metastasis (P = 0.03). Moreover, DNA-repair gene mutation was an independent unfavorable factor for recurrence-free survival (adjusted hazard ratio [HR] = 1.38, 95% CI: 1.00-1.91, P = 0.05) and disease-specific survival (adjusted HR=1.63, 95% CI: 1.04-2.57, P = 0.03) in this cohort. Overall, 3.4% of BRCA1/2-negative breast cancer patients carried germline mutations in the 16 DNA-repair genes, and the DNA-repair gene mutation carriers exhibited an aggressive phenotype and had poor survival compared with noncarriers.