BRCA1 expression and its combined low expression with PARP1 and ERCC1 predict chemotherapeutic response in ovarian cancer

Abstract

Objective: This study aimed to evaluate the associations of immunohistochemical expressions of various deoxyribonucleic acid repair proteins, either individually or combined, with the response to platinum-based chemotherapy and overall survival in epithelial ovarian cancer.Material and Methods: This retrospective cohort study included patients with epithelial ovarian cancer who were treated by primary cytoreductive surgery with adjuvant platinum-based chemotherapy at Songklanagarind Hospital between January 2008 and December 2019. Immunohistochemistry analysis of breast cancer type 1 (BRCA1), poly (ADP-ribose) polymerase 1 (PARP1), X-ray repair cross-complementing 1 (XRCC1), and excision repair cross-complementation group 1 (ERCC1) expression was performed. Logistic regression was used to evaluate factors associated with chemotherapeutic response and Cox regression was applied for survival analysis.Results: Chemotherapeutic response was achieved in 205 of 249 patients (82.3%). Low BRCA1 expression was associated with good response (odds ratio [OR] 5.01, 95% confidence interval [CI] 1.78–14.1) and favorable overall survival (hazard ratio 0.61, 95% CI 0.38–0.98). PARP1, XRCC1, and ERCC1 showed no significant predictive or prognostic roles; however, combined low expression of PARP1/BRCA1 (OR 7.62, 95% CI 1.69–34.31) and ERCC1/BRCA1 (OR 6.98, 95% CI 1.5–32.52) additively enhanced response compared to high/high expressions.Conclusion: This study provides evidence that epithelial ovarian cancer (EOC) with low BRCA1 expression is more likely to be responsive to platinum-based therapy and is associated with favorable overall survival compared to tumors with high BRCA1 expression. The study supports a potential therapeutic strategy involving co-depletion of PARP1/BRCA and ERCC1/BRCA1 expression, although additional studies are needed.