Background The optimal treatment of patients with FIGO stage IB grade 3 endometrial endometrioid adenocarcinoma remains unknown.

Objective To compare overall survival following treatment with a hysterectomy and adjuvant radiotherapy with or without chemotherapy in this group of patients.

Methods Patients diagnosed between January 2004 and January 2016 with FIGO stage IB grade 3 endometrial endometrioid adenocarcinoma treated with hysterectomy and postoperative radiotherapy with or without adjuvant concurrent chemotherapy were identified in the National Cancer Database. Overall survival was assessed with Kaplan-Meier curves. A Cox model was constructed to evaluate survival after controlling for confounding variables. A logistic regression model was used to reveal predictors of chemotherapy use.

Results A total of 2173 patients were included. The receipt of chemotherapy was associated with an increased 5-year overall survival from 67.6% to 75.6% (p=0.0313). This association trended toward statistical significance on multivariate analysis (adjusted HR (aHR) 0.80; 95% CI 0.63 to 1.01; p=0.0653). Other factors associated with improved survival were undergoing a lymphadenectomy, absence of lymphovascular space invasion, younger age, smaller tumor size, non-black race, and absence of comorbidities. Patients who underwent brachytherapy, had lymphovascular space invasion, were younger, were diagnosed in the more recent years, and were treated in higher volume centers were more likely to receive adjuvant chemotherapy.

Conclusion Adjuvant chemotherapy and radiation therapy were associated with an increase in survival in patients with FIGO stage IB grade 3 endometrial endometrioid adenocarcinoma compared with those treated with adjuvant radiotherapy alone.