Which patients with inoperable vulvar cancer may benefit from brachytherapy in addition to external beam radiation? A Surveillance, Epidemiology, and End Results analysis

PURPOSE: It is unknown whether brachytherapy after external beam radiation (EBRT + BT) results in improved outcomes compared with EBRT alone for patients with inoperable vulvar cancer. The purpose of this study was to compare survival outcomes for patients who received these treatment modalities. METHODS AND MATERIALS: Data between 1973 and 2011 from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) database were analyzed. Patients with Federation of International Gynecologists and Obstetricians stage I-IVA vulvar cancer treated with definitive EBRT + BT or EBRT alone were included. Patients with prior surgical resection were excluded. Disease-specific survival (DSS) and overall survival were compared using the Kaplan-Meier method and Cox proportional hazard models. RESULTS: A total of 649 patients were analyzed, of which 617 received EBRT alone and 32 received EBRT + BT. Median follow-up was 33 months in surviving patients. The use of brachytherapy declined from 16% of cases treated in 1973-1980 to 4% in 2001-2011 (p = 0.04). EBRT + BT vs. EBRT alone was not significantly associated with improved DSS (45% vs. 33% at 5 years) or overall survival (34% vs. 24% at 5 years) on univariate or multivariate analyses. On post hoc subgroup analyses, brachytherapy consolidation was associated with higher 5-year DSS in a composite subgroup that included patients with stage IVA disease, tumor >4 cm, or node-positive disease (52% vs. 27%, p = 0.02). CONCLUSIONS: Utilization of BT consolidation with EBRT for vulvar cancer is declining in the United States. EBRT + BT is not associated with improved survival compared with EBRT alone in the overall group of patients. Certain subgroups of patients might benefit from brachytherapy, but this hypothesis requires validation in future studies. (C) 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.