Meta-analysis of radiation therapy with and without adjuvant chemotherapy for malignant gliomas in adults

Abstract

The value of chemotherapy after standard postoperative external beam radiation in the treatment of malignant gliomas remains controversial. Despite recent recommendations from the Brain Tumor Cooperative Group that chemotherapy should be considered part of the standard treatment of patients with high-grade astrocytomas, several recent trials have questioned the efficacy of this approach. Using results from 16 randomized clinical trials involving more than 3000 patients, the authors compared the survival rates of patients who received radiation alone or radiation with chemotherapy. The combined data were analyzed using the statistical method of meta-analysis as described by DerSimonian and Laird. The estimated increase in survival for patients treated with combination radiation and chemotherapy was 10.1% at 1 year (95% confidence interval, 6.8, 13.3%) and 8.6% at 2 years (5.2, 12.0%). These absolute increases in survival (treated-control [TC]) in patients treated with chemotherapy represent relative increases (T-C)/C of 23.4% at 1 year (15.8, 30.9%) and 52.4% at 2 years (31.7, 73.2%). This survival advantage is conferred by several different chemotherapeutic agents. When the prognostic variables of age and histology are factored into the analysis, however, the data suggest that the survival benefit from chemotherapy occurs earlier in patients with anaplastic astrocytoma (AA) than in patients with glioblastoma. The authors concluded that chemotherapy is advantageous for patients with malignant gliomas and should be considered part of the standard therapeutic regimen. Additional randomized trials using optimal radiation and chemotherapy may still be needed to precisely define which subgroups of patients, based on prognostic variables, will benefit most from chemotherapy after radiation.