Breast cancer 1 (BRCA1) protein expression as a prognostic marker in sporadic epithelial ovarian carcinoma: an NCIC CTG OV.16 correlative study

Background: Breast cancer 1 (BRCA1) protein inactivation in sporadic ovarian carcinoma (OC) is common and low BRCA1 expression is linked with platinum sensitivity. The clinical validation of BRCA1 as a prognostic marker in OC remains unresolved. Patients and methods: In 251 patient samples from the NCIC CTG clinical trial, OV.16, BRCA1 protein expression was determined by immunohistochemistry. Results: For all patients, when BRCA1 score was analyzed as a continuous variable, there was no significant correlation between BRCA1 protein expression and progression-free survival (PFS) [adjusted hazard ratio (HR) = 1.15 (0.96-1.37), P = 0.12] or response rate [HR = 0.89 (0.70-1.12), P = 0.32]. In the 116 patients with minimal residual disease (RD), higher BRCA1 expression correlated significantly with worse PFS [HR = 1.40 (1.04-1.89), P = 0.03]. Subgroup analysis divided patients with minimal RD into low (BRCA1 <= 2.5) and high (BRCA1 >2.5) expression groups. Patients with low BRCA1 expression had a more favorable outcome [median PFS was 24.7 and 16.6 months in patients with low and high BRCA1, respectively; HR = 0.56 (0.35-0.89), P = 0.01]. Conclusions: This study suggests that BRCA1 protein is a prognostic marker in sporadic OC patients with minimal RD. Further research is needed to evaluate BRCA1 as a predictive biomarker and to target BRCA1 expression to enhance chemotherapeutic sensitivity.