Ovarian carcinosarcoma is a distinct form of ovarian cancer with poorer survival compared to tubo-ovarian high grade serous carcinoma

Abstract

BACKGROUND: Ovarian carcinosarcoma (OCS) is an uncommon, biphasic and highly aggressive ovarian cancer type, which has received relatively little research attention. METHODS: We curated the largest pathologically-confirmed OCS cohort to date, performing detailed histopathological characterisation, analysis of features associated with survival, and comparison against high grade serous ovarian carcinoma (HGSOC). RESULTS: 82 OCS patients were identified; overall survival was poor (median 12.7 months). 79% demonstrated epithelial components of high grade serous (HGS) type, while 21% were endometrioid. Heterologous elements were common (chondrosarcoma in 32%, rhabdomyosarcoma in 21%, liposarcoma in 2%); chondrosarcoma was more frequent in OCS with carcinomatous components of endometrioid type. Earlier stage, complete surgical resection, and treatment with platinum-containing chemotherapy were associated with prolonged survival; however, risk of relapse and mortality was high across all patient groups. Histological subclassification did not identify subgroups with distinct survival. Compared to HGSOC, OCS patients were older at diagnosis (P<0.0001), more likely to be FIGO stage I (P=0.025), demonstrated lower chemotherapy response rate (P=0.001) and had significantly poorer survival (P<0.0001). CONCLUSION: OCS represents a distinct, highly lethal form of ovarian cancer for which new treatment strategies are urgently needed. Aggressive adjuvant chemotherapy should be considered for all patients, including those with early stage disease.