Germline Pathogenic Variants and Clinical Outcomes in Asian Patients With Breast Cancer

Despite the importance of genetic testing for risk assessment and treatment in breast cancer, the prognostic impact of germline pathogenic variants (PVs), especially in Asian populations, is unclear. We assessed the impact of germline PVs in patients with early-stage breast cancer. This study included 7278 Japanese multihospital registry patients. PVs of ATM, BRCA1, BRCA2, CDH1, CHEK2, NBN, NF1, PALB2, PTEN, STK11, and TP53 were evaluated. PV and non-PV carriers were matched by age, histology, and stage. Associations between PVs and survival were assessed. The primary outcome was invasive disease-free survival (IDFS). Secondary outcomes included relapse-free survival (RFS), overall survival, and breast cancer-specific survival. We identified 320 (4.4%) patients with BRCA1/2 PVs and 79 (1.1%) with PVs other than BRCA1/2 (non-BRCA1/2). A total of 360 patients (BRCA1/2, n = 289; non-BRCA1/2, n = 71) were matched to 720 noncarriers. Patients with BRCA1/2 PVs had significantly shorter 10-year IDFS (adjusted hazard ratio (aHR) = 2.15; 95% confidence interval (CI), 1.61-2.86; p < 0.001); and RFS (aHR = 1.74; 95% CI, 1.25-2.44; p = 0.001) than noncarriers. Among patients with hormone receptor-positive HER2-negative breast cancer, BRCA1/2 PV carriers exhibited significantly shorter 10-year IDFS than noncarriers, even those with stage I/II disease (total, aHR = 2.23; 95% CI, 1.55-3.23; p < 0.001, Stage I/II, aHR = 2.22; 95% CI, 1.43-3.44; p < 0.001). There was no significant difference in 10-year IDFS between the non-BRCA1/2 PV carrier and noncarrier groups (aHR = 1.40; 95% CI, 0.67-2.93; p = 0.37). Asian patients with breast cancer carrying germline BRCA1/2 PV, even those with a low recurrence risk, have significantly shorter 10-year IDFS than noncarriers.