Adjuvant Pelvic Radiation Therapy±Vaginal Brachytherapy in Patients With High-risk Stage I or Stage II Uterine Papillary Serous, Clear Cell, and High-grade Endometrioid Carcinoma.

Abstract

Radiation therapy (RT) for stages I-II uterine papillary serous carcinoma (UPSC), clear cell (CC), and high-grade endometrioid (HGE) carcinoma present a treatment challenge. Regimens include external beam radiotherapy (EBRT) with or without brachytherapy. We examine the use of these radiation modalities in these endometrial cancers (EC) with respect to cause-specific survival (CSS). The Surveillance, Epidemiology, and End Results (SEER) database was queried for patients with AJCC stages I-II UPSC, CC, or HGE cancer treated with hysterectomy and RT between 1998 and 2008. Patients who did not receive adjuvant RT or received brachytherapy alone were excluded. CSS was evaluated by the Kaplan-Meier survival analysis and the log-rank test was used to compare CSS. Multivariate analysis was performed using the Cox proportional hazards regression model. Adjusted hazard ratios (HR) were calculated for risk of EC death. There were 1653 patients included in this analysis. The overall 100-month CSS for the entire cohort was 81.0%. The 100-month CSS was 85.3% for EBRT alone and 86.5% for EBRT+brachytherapy (P=0.72). Stage IC/IIA/IIB patients had a greater risk of EC death compared with stage IA/IB patients (adjusted HR=2.39; P<0.0001). Patients with UPSC and CC had a slightly higher risk of EC death compared with HGE (adjusted HR=1.01 [P=0.97] and 1.42 [P=0.02], respectively). On subset analysis, there was no difference in CSS with the addition of brachytherapy for UPSC (P=0.37), CC (P=0.27), or HGE cancer patients (P=0.42). Patients treated with brachytherapy in addition to EBRT did not demonstrate a reduced adjusted risk of EC death compared with EBRT alone (P=0.38). The addition of brachytherapy to adjuvant EBRT in stages I-II UPSC, CC, and HGE cancer did not demonstrate superior CSS. Thus, patients may not benefit from the addition of brachytherapy to EBRT.