Adjuvant treatment and outcomes for patients with stage IIIA grade 1 endometrioid endometrial cancer

The role and type of adjuvant therapy for patients with International Federation of Gynecology and Obstetrics (FIGO) stage IIIA grade 1 endometrioid endometrial adenocarcinoma are controversial. This retrospective cohort study aimed to determine associations between adjuvant therapy use and survival among patients with stage IIIA grade 1 endometrial cancer.Patients who underwent primary surgery for stage IIIA (FIGO 2009 staging) grade 1 endometrial cancer between January 2004 and December 2016 were identified in the National Cancer Database. Demographics and receipt of adjuvant therapy were compared. Overall survival was analyzed using Kaplan-Meier curves, log-rank test, and multivariable Cox proportional hazard models.Of 1120 patients, 248 (22.1%) received no adjuvant treatment, 286 (25.5%) received chemotherapy alone, 201 (18.0%) radiation alone, and 385 (34.4%) chemotherapy and radiation. Five-year overall survival rate was 83.0% (95% CI 80.1% to 85.6%). Older age, increasing comorbidity count, and lymphovascular space invasion status were significant negative predictors of survival. Over time, there was an increasing rate of chemotherapy (45.4% in 2004-2009 vs 69.2% in 2010-2016; p<0.001). In the multivariable analysis, chemotherapy was associated with significantly improved overall survival compared with no adjuvant therapy (HR 0.49 (95% CI 0.31 to 0.79); p=0.003). There was no survival association when comparing radiation alone with no treatment, and none when adding radiation to chemotherapy compared with chemotherapy alone. Those with lymphovascular space invasion (n=124/507) had improved overall survival with chemotherapy and radiation (5-year overall survival 91.2% vs 76.7% for chemotherapy alone and 27.3% for radiation alone, log-rank p<0.001), but there was no survival difference after adjusting for age and comorbidity (HR 0.25 (95% CI 0.05 to 1.41); p=0.12).The use of adjuvant chemotherapy for the treatment of stage IIIA grade 1 endometrial cancer increased over time and was associated with improved overall survival compared with radiation alone or chemoradiation. Patients with lymphovascular space invasion may benefit from combination therapy.