LAUSR

Objectives: Evaluate if the addition of adjuvant chemotherapy to radiation therapy improves survival of patients with high-intermediate stage I endometrioid endometrial carcinoma with lympho-vascular invasion (LVSI). Methods: Patients without a history of another tumor, diagnosed between 2010 and 2015 with pathological stage I endometrioid endometrial adenocarcinoma with LVSI who underwent hysterectomy with at least 10 lymph nodes removed, and met the GOG-99 criteria for high-intermediate risk were identified in the National Cancer Database. Those who received adjuvant radiation therapy with or without adjuvant chemotherapy (defined as treatment received within 6 months from surgery) and had at least one month of follow-up were selected for further analysis. Overall survival (OS) was compared with the log-rank test following generation of Kaplan-Meier curves. A Cox multivariate model was constructed to control for confounders. Results: A total of 2342 patients who met the inclusion criteria were identified; 1938 (82.7%) patients received radiation therapy only (RT) while 404 (17.3%) received chemoradiation (CRT). The majority (74.9%) of patients received brachytherapy (VBT) while 16.8% received external beam radiation therapy (EBRT), and 8.3% received combination of both VBT and EBRT. Rate of adjuvant chemotherapy administration did not differ based on the type of radiation therapy administered; 17.9%, 17% and 17.9% for patients who received EBRT, VBT or combination of both respectively, p=0.88. Patients who received CRT were younger (median age 62 vs 65 years, p 0.05. Median follow-up in the RT and CRT groups was 41.0 and 45.2 months respectively. There was no difference in OS between patients who received RT and CRT, p=0.53; 4-year OS rates were 85.8% and 82.6% respectively. CRT did not confer a survival benefit for grade 2 (p=0.98) or grade 3 (p=0.34) tumors. After controlling for patient age, race, insurance status, presence of comorbidities, tumor grade, size, and depth of myometrial invasion, CRT was not associated with better survival (HR: 0.95, 95% CI: 0.71, 1.28). Conclusions: In a large cohort of patients with high-intermediate risk FIGO stage I endometrioid endometrial adenocarcinoma with lymph-vascular invasion, the addition of chemotherapy to radiation therapy was not associated with a survival benefit.