Epithelial ovarian cancer (EOC) accounts for 140,000 deaths annually worldwide and is the leading cause of gynecologic cancer-related mortality in the United States. Approximately, 70% of EOC patients present with advanced disease, and although the majority will respond to surgery and first-line chemotherapy, most of these responses are not durable: more than 90% of suboptimal surgically debulked patients and 70% of optimally debulked patients will relapse in 18 to 24 months. The major subtypes of ovarian carcinomas include high-grade serous carcinoma (HGSC), endometrioid carcinoma (EC), clear cell carcinoma (CCC), low grade serous carcinoma (LGSC), and mucinous carcinoma (MC). More recently, four molecular subtypes (C1/mesenchymal, C2/immune, C4/differentiated, and C5/proliferative) have been identified in HGSC and validated by gene expression profiling, and these are associated with differential clinical outcomes.