Adjuvant Therapy Use and Survival in Stage II Endometrial Cancer

Radiotherapy (RT) is an established adjuvant treatment for stage II endometrioid endometrial carcinoma (EEC). The role of chemotherapy (CT) in stage II EEC is less proven. We used the National Cancer Data Base to identify factors associated with adjuvant CT in stage II EEC and to explore whether receipt of CT was associated with improved overall survival (OS).

Women diagnosed in 2010 to 2013 with International Federation of Obstetrics and Gynecology stage II EEC (grades 1-3) after hysterectomy and bilateral salpingo-oophorectomy were identified in the National Cancer Data Base. Multivariable logistic regression was used to identify covariates associated with receipt of CT. Overall survival among patients receiving RT, CT, or chemoradiotherapy (CRT) after surgery was compared using Kaplan-Meier estimates, the log-rank test, Cox proportional hazards regression, and propensity score matching.

We identified 6102 stage II EEC patients. There were 358 patients (6%) who received adjuvant CT alone and 525 (9%) who received CRT; the remainder received RT alone (n = 1906; 31%) or no adjuvant treatment (n = 3313; 54%). The presence of lymphovascular invasion (odds ratio, 3.58; P < 0.001) and grade 3 disease (odds ratio, 3.40; P < 0.001) was strongly associated with receipt of CT or CRT. The OS at 3 years for the entire cohort was 89%. On multivariable analysis, CT versus RT was associated with worse OS (hazard ratio [HR], 2.12 [95% confidence interval, 1.46-3.06]; P < 0.001), whereas CRT versus RT was not associated with improved OS (HR, 1.07 [95% confidence interval, 0.71-1.62]; P = 0.781). After propensity score matching, there remained no difference in OS between RT and CRT (HR, 1.14; P = 0.614).

Patients with stage II EEC have an excellent prognosis, and most undergo observation or receive adjuvant RT in the United States. Receipt of CT (alone or with RT) was not associated with an OS advantage compared with RT alone in this observational cohort. Randomized trials will help clarify the role of CT in stage II patients.