Impact of germline BRCA1/2 mutations on response to neoadjuvant systemic therapy and prognosis in breast cancer: a propensity score matched cohort study.

Background: We investigated whether germline BRCA1/2 pathogenic variants (PVs) influence treatment response and survival outcomes in breast cancer patients treated with neoadjuvant chemotherapy (NCT). Using propensity score matching (PSM) to control for variations in treatment and clinicopathological characteristics, this study aimed to evaluate the influence of BRCA1/2 mutations on prognosis and treatment efficacy, providing insights for optimizing therapeutic strategies and improving patient outcomes.

Methods: We conducted a retrospective cohort study using data from two institutions. The study analyzed breast cancer patients who underwent germline BRCA1/2 testing and received NCT followed by curative resection and standard adjuvant therapy from January 2001 to January 2019. PSM was used to balance confounding variables.

Results: Among 411 patients included, 86 have BRCA1/2 mutations. After matching, BRCA1/2 PV carriers had a higher pCR rate (40.0%) compared to wild-type patients (26.5%, OR = 1.85, 95% CI: 1.07-3.22, P = 0.029). They also exhibited a significantly lower 5-year DM rate (4.7% vs. 18.2%, OR = 0.22, 95% CI: 0.08-0.65, P = 0.006). Among pCR patients, outcomes were excellent regardless of BRCA1/2 status. For non-pCR patients, BRCA1/2 PV carriers had better DMFS (hazard ratio (HR) = 0.27, 95% confidence interval (CI) = 0.09-0.81, P = 0.02), though overall survival differences were not significant (HR = 0.47, 95% CI = 0.15-1.47, P = 0.197).

Conclusions and relevance: Germline BRCA1/2 mutations are associated with higher pCR rates and improved DMFS in breast cancer patients treated with NCT. These findings emphasize the enhanced chemosensitivity of BRCA-associated tumors and the importance of genetic testing in treatment planning. Further research is needed to validate these findings and optimize treatment strategies.