Patient characteristics, treatment patterns, and clinical outcomes in HER2-negative early breast cancer by germline BRCA status.

Introduction: This study evaluated treatment patterns and survival among patients receiving systemic therapy for HER2- early breast cancer (eBC).

Methods: A retrospective observational cohort study was used to evaluate gBRCA testing rates; treatment patterns and survival between patients tested positive for gBRCA (gBRCAm) and randomly selected patients with wildtype BRCA (gBRCAwt).

Results: gBRCA testing rate was 8.2%, and gBRCA mutated rate was 9.8%. Most hormone receptor-positive [HR+]/HER2- patients received adjuvant only treatment, while triple negative breast cancer [TNBC] patients commonly received neoadjuvant only treatment. Among HR+/HER2- patients, 60-month survival was numerically greater for gBRCAwt than gBRCAm. In TNBC patients, gBRCAm ware associated with numerically better invasive disease-free survival (IDFS) and distant disease-free survival (DDFS) compared to gBRCAwt.

Conclusions: The study survival outcomes among HER2- patients are not significantly different based on gBRCA mutation status, although gBRCAm status is associated with slightly poorer survival. Among patients with structured electronic health record data, the gBRCA testing rate was 8.2%, with a mutation rate of 9.8% among those tested. While these rates reflect under-documentation in electronic health records, they highlight the need for improved capture of genetic testing in real-world settings.