Disease-specific survival of type I and type II epithelial ovarian cancers—stage challenges categorical assignments of indolence & aggressiveness

Epithelial ovarian cancers (EOC) consist of several sub-types based on histology, clinical, molecular and epidemiological features that are termed “histo-types”, which can be categorized into less aggressive Type I and more aggressive Type II malignancies. This investigation evaluated the disease-specific survival (DSS) of women with Type I and II EOC using histo-type, grade, and stage. A total of 47,789 EOC cases were identified in the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) data. Survival analysis and log rank test were performed to identify a 2-tiered classification (grade 1 vs. grade 2 & 3) for serous EOC. DSS of early stage serous EOC for grade 2 was significantly different from grade 3 indicating that a 2-tier classification for serous EOC applied only to late stage. DSS of Type I EOC was much better than Type II. However, DSS was 33–52% lower with late stage Type I than with early stage Type I indicating that Type I ovarian cancers should not be considered indolent. Early stage Type II EOC had much better DSS than late stage Type II stressing that stage has a large role in survival of both Type I and II EOC.