Patterns of adjuvant radiation usage and survival outcomes for stage I endometrial carcinoma in a large hospital-based cohort

Abstract

Objective: Two randomized trials have demonstrated a local control advantage in the absence of a survival advantage for the addition of adjuvant radiation therapy (RT) to surgery in patients with stage I endometrial adenocarcinoma (EC). This study analyzed the National Cancer Data Base (NCDB) to evaluate the impact of adjuvant RT on overall survival (OS) for patients with stage I EC.

Methods: Patients with EC who underwent total hysterectomy/bilateral salpingo-oophorectomy between 2004 and 2011 were queried. Only those with AJCC stage pT1N0M0 were included. Patients surviving <4months excluded. Adjuvant RT included external beam RT (EBRT), brachytherapy, or external RT+brachytherapy. OS was analyzed using the Kaplan-Meier method. Multivariate Cox regression analysis and propensity matched analysis were performed to assess the impact of covariates on OS.

Results: There were 61,697 patients included. Most women (83.9%) did not receive adjuvant RT. Adjuvant RT usage increased with increasing stage/grade. Usage of brachytherapy alone decreased with increasing stage/grade (78.2% for IA/G1 to 36.1% for IB/G3) corresponding to an increase in the use of EBRT (21.8% for IA/G1 to 53.9% for IB/G3). On multivariable analysis, adjuvant EBRT (HR 0.83, 95%CI 0.74-0.93, p=0.002) and brachytherapy (HR 0.82, 95%CI 0.74-0.93, p=0.002) were each associated with improved survival for women with stage IB. In the propensity matched cohort, RT was associated with improved survival (0.85, 95% CI 0.78-0.92, p<0.001).

Conclusion: The use of adjuvant RT for women with stage I EC is highly dependent on stage/grade and is associated with improved survival for stage IB.

Keywords: Brachytherapy; Chemotherapy; Combined modality therapy; Endometrial cancer; Radiation therapy.