Adjuvant Treatment of Stage I-II Serous Endometrial Cancer: A Single Institution 20-Year Experience.

Background: Serous endometrial carcinoma (SEC) is a high-risk subtype of endometrial cancer. The effectiveness of multiple adjuvant therapies, namely chemotherapy (CT), radiotherapy (RT), and sequential/concurrent chemotherapy with radiotherapy (CRT), have previously been investigated. However, optimal management of early-stage SEC remains unclarified. Methods: All cases of early-stage SEC (FIGO 2009 stages I-II) treated in our institution from 2002 to 2019 were identified. Patient data were documented until September 2023. Overall survival (OS) and disease-free survival (DFS) were computed using Kaplan-Meier estimates and Cox's proportional hazard model; descriptive statistical analysis was performed. Results: A total of 50 patients underwent total hysterectomy-bilateral salpingo-oophorectomy and omentectomy, displaying stage IA (60%), IB (24%), and II (16%) disease. The median follow-up was 90.9 months. Patients underwent adjuvant CRT (n = 36, 72%), CT (n = 6, 12%), or RT (n = 6, 12%). Two patients were observed and excluded from analyses. The 42 patients who received radiotherapy had pelvic external beam radiotherapy (n = 10), vaginal brachytherapy (n = 21), or both (n = 11). CRT had better OS (HR 0.14, 95%CI 0.04-0.52, p < 0.005) and DFS (HR 0.25, 95%CI 0.07-0.97, p = 0.05) than CT alone. RT displayed no OS or DFS benefits compared to CT/CRT. Recurrences were mostly distant. Acute and late G3-4 toxicities were primarily hematologic. Conclusions: Our data underline the challenge of treating SEC. CRT appears to be superior to CT alone but not to RT. Most recurrences were distant, highlighting the need for optimized systemic treatment options.