Objective: Uterine carcinosarcoma is a rare, aggressive subtype of endometrial cancer. Treatment consists of hysterectomy, bilateral salpingo-oophorectomy, and lymphadenectomy (LND). The survival benefit of LND in relation to adjuvant radio- and/or chemotherapy is unclear. We evaluated the impact of LND on survival in relation to adjuvant therapy in uterine carcinosarcoma. Methods: Retrospective data on 1,140 cases were combined from the Netherlands Cancer Registry (NCR) and the nationwide network and registry of histo- and cytopathology in the Netherlands (PALGA). LND was defined as the removal of any nodes. Additionally, cases where 10 nodes or less (LND ≤10) or more than 10 nodes (LND > 10) were removed were analyzed separately. Adjuvant therapy was evaluated as radiotherapy, chemotherapy, or radiochemotherapy. Associations were analyzed by χ2 test, log-rank test, and Cox regression analysis. Results: Overall survival (OS) had improved after total abdominal hysterectomy with bilateral salpingo-oophorectomy with LND > 10 (HR 0.62, 95% CI 0.47–0.83). Adjuvant therapy was related to OS with an HR of 0.64 (95% CI 0.54–0.75) for radiotherapy, an HR of 0.65 (95% CI 0.48–0.88) for chemotherapy, and an HR of 0.25 (95% CI 0.13–0.46) for radiochemotherapy. Additionally, adjuvant treatment was related to OS when lymph nodes were positive (HR 0.22, 95% CI 0.11–0.42), but not when they were negative. Conclusion: LND is related to improved survival when more than 10 nodes are removed. Adjuvant therapy improves survival when LND is omitted, or when nodes are positive
