Clinical outcomes and Oncotype DX Breast Recurrence Score® in early-stage BRCA-associated hormone receptor-positive breast cancer

Background: BRCA-associated breast cancers tend to have distinctive features compared to sporadic breast cancers; further characterization can aid in optimizing treatment. Methods: The study evaluated a patient cohort with early-stage estrogen receptor positive, HER2 negative invasive breast cancer who had Oncotype DX Breast Recurrence Score® analysis and genetic testing for hereditary breast and ovarian cancer syndrome. Data on patients and their breast cancers with outcomes were collected and analyzed. Results: 745 patients were included, of whom 33 had pathogenic BRCA mutations (8 BRCA1, 25 BRCA2). Patients with BRCA mutations were younger and received more adjuvant chemotherapy, but less endocrine therapy and radiation therapy. BRCA-associated breast cancers had less progesterone receptor expression, higher nuclear grade, and higher Oncotype DX Breast Recurrence Scores® with median Recurrence Score® 29, compared to 16 in cancers without mutations (p < 0.0001). Breast cancer recurrence developed in 18% of patients with BRCA mutations and 9% of patient without mutations, although multivariate analysis of relapse-free survival was not significant, HR 1.519 (95% confidence interval [CI] 0.64–3.58; p = 0.3401). After adjusting for Recurrence Score®, overall survival by BRCA status was improved HR 0.448 (95% CI 0.06–3.34; p = 0.4333). Conclusions: BRCA-associated early-stage hormone receptor-positive breast cancers have higher Oncotype DX Breast Recurrence Score® compared to those without mutations. BRCA status did not significantly impact relapse-free survival and overall survival. Larger clinical trials are needed to further assess the findings, and if confirmed, could impact clinical management of BRCA-associated breast cancers.