To evaluate the use of adjuvant therapy after primary surgery for stage I-III uterine carcinosarcoma (CS).

A multi-institutional retrospective study of women with stage I-III CS was conducted. Analyses were stratified by stage (I/II and III). Patients were categorized according to adjuvant therapy: observation (OBS), radiation (RT), chemotherapy (CT) or multimodal therapy (CT+RT). Overall survival (OS) and progression-free survival (PFS) were analyzed using log-rank tests and Cox proportional hazards models.

303 patients were identified across four institutions: 195 with stage I/II and 108 with stage III disease. In stage I/II disease, 75 (39.9%) received OBS, 33 (17.6%) CT, 37 (19.7%) RT, and 43 (22.9%) CT+RT. OBS was associated with a fourfold increased risk of death compared to CT (adjusted hazard ratio (aHR)=4.48, p=0.003). Patients receiving CT+RT had significantly improved PFS compared to those receiving CT alone (aHR=0.43, p=0.04), but no difference in OS. In the stage III cohort, 16 (15.0%) received OBS, 34 (31.8%) CT, 20 (18.7%) RT, and 37 (34.6%) CT+RT. OBS was associated with worse OS and PFS compared to CT (OS: aHR=2.46, p=0.04; PFS: aHR=2.39, p=0.03, respectively). A potential improvement in PFS was seen for those treated with CT+RT compared to CT alone, however it was not statistically significant (aHR=0.53, p=0.09).

Observation after surgery was associated with poor outcomes in uterine CS compared to CT and RT alone. Multimodality therapy for women with stage I/II disease was associated with improved PFS compared to chemotherapy alone. Novel treatment options are needed to improve outcomes in this aggressive disease.