Correlation Between Histopathology and Chemotherapy Response in Epithelial Ovarian Tumors

BACKGROUND: Epithelial ovarian carcinoma comprises biologically distinct histological subtypes with differing chemosensitivity; however, neoadjuvant carboplatin-paclitaxel is commonly administered using uniform treatment protocols. AIM: This study aimed to determine whether histopathological subtype predicts multimodal response to neoadjuvant carboplatin-paclitaxel in advanced epithelial ovarian carcinoma. METHODS: In this prospective-retrospective observational study, 126 women with advanced epithelial ovarian carcinoma received platinum-taxane neoadjuvant chemotherapy followed by interval debulking surgery. Histological subtype, radiological response based on Response Evaluation Criteria in Solid Tumors (RECIST), serum cancer antigen 125 (CA-125) kinetics, omental and adnexal Chemotherapy Response Score (CRS 1-3), and extent of cytoreduction were recorded. Associations with histological subtype were analyzed using chi-square tests and analysis of variance (ANOVA). RESULTS: High-grade serous carcinoma (107/126, 84.9%) was the most common subtype, followed by low-grade serous carcinoma (12/126, 9.5%); mucinous, endometrioid, and clear cell tumors were infrequent. High-grade serous carcinomas demonstrated significant tumor shrinkage, marked decline in CA-125 levels, and predominantly CRS 2-3 responses. Low-grade serous and mucinous tumors showed minimal radiological regression, little change in CA-125, and uniformly CRS 1 responses. Endometrioid and clear cell tumors also showed CRS 1 responses but achieved favorable cytoreduction, although case numbers were very small. Optimal cytoreduction was achieved in 77/107 (72.0%) high-grade serous, 9/12 (75.0%) low-grade serous, 1/3 (33.3%) mucinous, and all endometrioid (3/3, 100.0%) and clear cell tumors (1/1, 100.0%). Neoadjuvant chemotherapy and surgery were well tolerated, with no treatment-related or perioperative mortality. CONCLUSION: Histopathological subtype is a major determinant of response to neoadjuvant carboplatin-paclitaxel in epithelial ovarian carcinoma. Integrating RECIST response, CA-125 kinetics, CRS, and residual disease provides a pragmatic, histology-informed framework for treatment planning, particularly in settings where molecular profiling is limited.