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

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/m 2 temozolomide for 42 days of radiotherapy, followed by 6 courses every 28 days; the first course was 150 mg/m 2 for 1–5 days, and the subsequent courses were 200 mg/m 2 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 (Adv Clin Exp Med 2015, 24, 2, 279–287).