Clinical Course of Hormone-Positive Her2/Neu-Negative Breast Cancer in Carriers of Mutations in the BRCA2 Gene Compared with BRCA1

Research objective: comparative analysis of the clinical course of hormone-positive Her2/neu-negative breast cancer associated with mutations in the BRCA1 and BRCA2 genes. Materials and methods. Data from 474 patients with germline mutations in the BRCA1/2 genes were analyzed, covering all molecular-biological subtypes of breast cancer. The study cohort included 100 patients with stage I–IIB hormone-positive, HER2/neu-negative breast cancer, who were divided into two groups: the main group of 50 patients with a mutation in the BRCA2 gene and the control group of 50 patients with a mutation in the BRCA1 gene. The frequency of distant, local, and regional recurrences, breast cancer mortality, and the composite rate of any adverse event were evaluated. Results. The BRCA2 group had higher rates of adverse events compared with BRCA1: distant recurrence: 8% vs. 2% (RR 4.00; 95% CI 0.46–34.7; p=0.36); local recurrence: 10% vs. 6% (RR 1.67; 95% CI 0.42–6.63; p=0.72); regional recurrence: 8% vs. 0% (RR 9.00; 95% CI 0.50–162; p=0.12); death from breast cancer: 6% vs. 2% (RR 3.00; 95% CI 0.32–28.1; p=0.62). Adverse events were reported in 32% of patients in the BRCA2 group compared with 10% in the BRCA1 group (RR 3.20; 95% CI 1.27–8.06; p=0.015). Conclusion. Despite a favorable hormone-positive profile, patients with a BRCA2 mutation have higher risks of progression, recurrence, and mortality compared to patients with a BRCA1 mutation.