Most patients with epithelial ovarian cancers (EOC) present with advanced-stage disease because of non-specific symptoms and lack of reliable strategies for early diagnosis. Cancer antigen 125 (CA-125) is suggested as a useful prognostic biomarker, its serum level is raised in over 80.0% of patients with EOC. Primary debulking surgery (PDS) followed by chemotherapy is the conventional treatment, but neoadjuvant chemotherapy followed by interval debulking surgery (NACT-IDS) is offered to patients with unresectable disease. There are inconsistencies regarding the role of preoperative CA-125 serum levels to adopt in stratifying patients for treatment choice that offers the most benefit. This review aimed to determine the role of preoperative CA-125 levels in predicting optimal cytoreduction and the association between optimal cytoreduction and survival outcome in patients with EOC. Three electronic databases CINAHL, Cochrane library and PubMed were searched for potentially relevant articles from 2016 to 2021 on the role of preoperative CA-125 levels in predicting optimal cytoreduction and survival in patients with epithelial ovarian carcinomas. In patients who underwent NACT-IDS, a lower preoperative CA-125 value is a predictor of optimal cytoreduction and an increase in preoperative CA-125 value is consistently associated with a decrease in optimal cytoreduction. There was insufficient data to assess overall survival. However, a raised preoperative CA-125 level is poor predictor of chance of achieving optimal cytoreduction and the rate of optimal cytoreduction was a weak predictor of overall survival in women who had primary debulking surgery.