Addition of chemotherapy to hypofractionated radiotherapy for glioblastoma: practice patterns, outcomes, and predictors of survival

This study evaluated practice patterns, outcomes, and predictors of survival with respect to the addition of chemotherapy to definitive hypofractionated radiation therapy (HFRT) for glioblastoma in a general patient population. The National Cancer Data Base was queried for patients diagnosed with glioblastoma between 2005 and 2012 that received definitive HFRT with or without chemotherapy. Patient, tumor, and treatment parameters were extracted. Statistics included Kaplan-Meier analysis to evaluate overall survival (OS) as well as Cox proportional hazards modeling to determine variables associated with receipt of chemotherapy and OS. Propensity score matching was performed in order to assess groups in a balanced manner while reducing indication biases. 693 patients met the inclusion criteria, of which 297 (42.9%) received HFRT alone, while 396 (57.1%) received chemotherapy and radiation therapy. Median follow-up was 5.2 months. Factors independently associated with chemotherapy delivery included age <= 65, methylated MGMT, and Asian race. Chemotherapy use was associated with improved median OS (6.8 vs. 4.3 months, p < 0.001). This persisted in both age groups of age <= 65 (8 vs. 4.4 months, p < 0.001) and > 65 years (6.1 vs. 4.3 months, p = 0.002) as well as on propensity-matched analysis (6.0 vs. 4.3 months, p < 0.001). In this patient population, novel independent predictors of OS were identified, which included the addition of chemotherapy (p < 0.001), receipt of surgery other than biopsy (both p < 0.05), and treatment at an academic institution (p = 0.002). Addition of chemotherapy to definitive HFRT was associated with improved OS in patients <= 65 and > 65 years of age. Chemotherapy was an independent predictor of OS, along with receipt of surgery and treatment at an academic institution.