The Impact of Surgery on the Efficacyof Adjuvant Therapy in Glioblastoma Multiforme

Abstract

BACKGROUND: Glioblastoma multiforme (GBM) is the most malignant brain tumor. Surgery still remains a fundamental part of treatment in GBM, followed by radiotherapy and chemotherapy. OBJECTIVES: The aim of the study was to assess the impact of surgery on the efficacy of adjuvant therapy in patients with glioblastoma multiforme. MATERIAL AND METHODS: The study involved 181 patients: 50 treated with adjuvant radiotherapy (RTH) only (60 Gy in daily 2Gy fractions) and 131 treated with postoperative radiochemotherapy (RTH-CHT) (60 Gy, 2Gy/d)+75 mg/m2 temozolomide for 42 days of radiotherapy, followed by 6 courses every 28 days; the first course was 150 mg/m2 for 1-5 days, and the subsequent courses were 200 mg/m2 for 1-5 days). Overall survival (OS) and disease-free survival (DFS) were assessed. The statistical analysis entailed the log-rank test, Kaplan-Meier curves and Cox proportional hazards regression; the threshold of statistical significance was set at p=0.05. RESULTS: Median OS and DFS were significantly increased (p=0.001) in the RTH-CHT group compared with the RTH group: 9.77 months vs 6.38 months for OS, and 8.4 months vs 4.33 months for DFS. After radical surgery, RTH-CHT extended OS by 5.3 months and DFS by 4.5 months in comparison to RTH. In patients who underwent non-radical surgery, the type of adjuvant therapy made no difference in either OS or DFS. In the RTH-CHT group, OS and DFS depended on the extent of the surgery, and were significantly longer in patients who underwent radical surgery (OS: p=0.03128; DFS: p=0.01206). In the RTH group, the type of surgery had no effect on survival. CONCLUSIONS: Radiochemotherapy significantly prolongs OS and DFS compared with radiotherapy alone in GBM patients who have undergone radical removal of the tumor. Among patients who had non-radical surgery, the type of adjuvant treatment has no effect on OS or DFS.