Clinical characteristics and survival outcomes in ovarian carcinosarcoma compared to serous carcinoma: A population-based analysis.

e17605 Background: Serous ovarian carcinoma (SOC) is the most common form of ovarian cancer, whereas ovarian carcinosarcoma (OCS) is a much rarer subtype. This study compares clinical outcomes and survival predictors for ovarian carcinosarcoma versus (vs) ovarian serous carcinoma. Methods: Data for ovarian serous carcinoma and carcinosarcoma cases diagnosed between 2000 and 2021 were extracted from the Surveillance, Epidemiology, and End Results (SEER) database. Demographic and treatment characteristics were summarized. Kaplan-Meier survival analysis was used to evaluate survival outcomes and its predictors were assessed using multivariable Cox proportional hazards models. Results: The study included 31,977 patients, 731 (2%) were diagnosed with OCS and 31,246 (98%) with SOC. The SOC cohort predominantly comprised patients aged 50–74 years (67%), with 86% identifying as white race and 89% as non-Hispanic/ non-Latino. Most SOC patients presented with distant disease (78%) and Grade 3 or undifferentiated tumors (81%). Surgery was performed in 96% of cases, and 81% received chemotherapy. Additionally, 57% of SOC patients had a median household income under $75,000, and 61% lived in metropolitan areas with populations exceeding 1 million. The OCS cohort consisted primarily of patients aged 55–79 years (71%), with 86% identifying as white and 89% as non-Hispanic/ non-Latino. Advanced disease was common, with 72% presenting at late stage and almost all having Grade 3 or undifferentiated tumors (99%). Surgery was performed in 98% of OCS cases, and 76% received chemotherapy. Most OCS patients lived in metropolitan areas with populations over 1 million (59%), and 61% reported a median household income under $75,000. Median survival for OCS was significantly shorter at 16 months compared to 49 months for SOC. The 5-year survival was also lower in OCS (25% vs. 43%) as was overall survival (21% vs. 28%). OCS histology was associated with a higher mortality risk compared to SOC (HR = 1.795, 95% CI: 1.652–1.950, p < 0.0005). Younger age, lower stage at diagnosis, and receipt of surgery or chemotherapy were significant predictors of survival in both cohorts. Conclusions: OCS is a rare aggressive subtype of ovarian cancer with markedly worse survival outcomes compared to SOC, even after adjusting for demographic and clinical factors. These findings highlight the need for further research to enhance therapeutic strategies for OCS.