Receipt of brachytherapy is an independent predictor of survival in glioblastoma in the Surveillance, Epidemiology, and End Results database

Abstract

Introduction: There has been a resurgence of interest in brachytherapy as a treatment for glioblastoma, with several currently ongoing clinical trials. To provide a foundation for the analysis of these trials, we analyze the Surveillance, Epidemiology, and End Results (SEER) database to determine whether receipt of brachytherapy conveys a survival benefit independent of traditional prognostic factors. Materials and methods: We identified 60,456 glioblastoma patients, of whom 362 underwent brachytherapy. We grouped patients based on receipt of brachytherapy and compared clinical and demographic variables between groups using Student’s t-test and Pearson’s chi-squared test. We assessed survival using Kaplan–Meier curves and Cox proportional hazards models. Results: Median overall survival was 16 months in patients who received brachytherapy compared to 9 months in those who did not (log-rank p < 0.001). Patients who underwent brachytherapy tended to be younger (p < 0.001), suffered from smaller tumors (< 4 cm, p < 0.001), and were more likely to have undergone gross total resection (GTR, p < 0.001). In univariable Cox models, these variables were independently associated with improved overall survival. Additionally, improved survival was associated with known receipt of chemotherapy (HR 0.459, p < 0.001), external beam radiation (HR 0.447, p < 0.001), and brachytherapy (HR 0.637, p < 0.001). The association between brachytherapy and improved survival remained robust (HR 0.859, p = 0.031) in a multivariable model that adjusted for patient age, tumor size, tumor location, GTR, receipt of chemotherapy, and receipt of external beam radiation. Conclusion: Our SEER analysis indicates that brachytherapy is associated with improved survival in glioblastoma after controlling for age, tumor size/location, extent of resection, chemotherapy, and external beam radiation.