Vaginal Cuff Brachytherapy versus Whole Pelvic Radiation Therapy Plus Vaginal Cuff Brachytherapy Boost for Stage II Endometrioid Adenocarcinoma

Abstract

Hysterectomy and bilateral salpingo-oophorectomy with or without lymph node evaluation is the standard treatment for most endometrial cancer patients. For stage II endometrioid adenocarcinomas, adjuvant whole pelvic radiation therapy (WPRT) is typically recommended for local control of disease. Consensus regarding whether vaginal cuff brachytherapy (VCBT) alone is sufficient for stage II disease has not been established. We evaluated outcomes of patients with stage II endometrioid adenocarcinoma treated with VCBT alone or WPRT with VCBT boost (WPRT+VCBT). A retrospective review was conducted of node negative FIGO stage II endometrioid adenocarcinoma patients treated at Mayo Clinic (Arizona, Florida, and Rochester) between 2004-2018. Patients received post-operative WPRT+VCBT or VCBT alone. Information was collected regarding baseline characteristics (age, tumor grade, tumor size, margins, lower uterine involvement, depth of tumor invasion, lymph node evaluation, and lymphovascular invasion), treatment characteristics, and outcomes. Comparisons of baseline and treatment characteristics between VCBT alone and WPRT+VCBT were made using Wilcoxon rank sum test or Fisher’s exact test. Survival and recurrence comparisons were made using log rank tests. 52 women were included (38 VCBT alone and 14 WPRT+VCBT) with a median follow up of 3.9 years (range 13 days – 11.1 years). 41 patients had surgical lymph node evaluation with a median of 21 lymph nodes removed (range 1-104). Median WPRT dose was 45 Gy in 25 fractions with a median VCBT boost dose of 12 Gy in 3 fractions. Median VCBT alone dose was 21 Gy in 3 fractions. There was no difference in positive margin status (12% vs 4%; p = 0.44), depth of invasion (67% vs 55%; p = 0.17), lymphovascular invasion (25% vs 40%; p = 0.49), or chemotherapy use (21% vs 18%; p = 1.0) between WPRT+VCBT and VCBT alone. Pathological grade was lower for VCBT alone patients, although this did not reach significance (Grade 1: 50% VCBT alone vs. 21% WPRT+VCBT, p = 0.061). There was no significant difference between WPRT+VCBT and VCBT alone regarding rates of death (14% vs 5%; p = 0.42), vaginal recurrence (0% vs 5%; p = 0.42), pelvic recurrence (7% vs 5%; p = 0.85), para-aortic recurrence (7% vs 3%; p = 0.42), any recurrence (14 vs 13%; p = 0.93), or distant metastasis (7% vs 8%; p = 0.67). For all patients, the 5-year cumulative incidence of death and any recurrence was 9% and 13%, respectively. There was no significant difference in patterns of recurrence or overall survival between treatment with WPRT+VCBT or VCBT alone for patients in this study. While this study is hypothesis generating, our data suggest that VCBT alone may be sufficient treatment for surgically staged node negative stage II endometrioid adenocarcinoma, potentially sparing patients the toxicities associated with WPRT+VCBT.