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

Purpose: 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). Methods: 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. Results: 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). Conclusions: 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.