Positron emission tomography 11C-methionine and survival in patients with low-grade gliomas

BACKGROUND. Considerable numbers of patients with low-grade gliomas experience an early malignant course and may benefit from aggressive treatment. These patients are difficult to identify using established prognostic factors. A retrospective study was performed to determine whether the C-11-methionine uptake in tumor is a survival factor in adult patients with supratentorial gliomas classified as World Health Organization Grade 2. METHODS. The authors identified 89 patients with histologically confirmed low-grade gliomas in whom an C-11-methionine positron emission tomography (PET) scan had been performed as part of the diagnostic tumor investigation from 1983 to 1998. Clinical data were collected, and the PET scans were re-evaluated according to a fixed protocol. The C-11-methionine uptake in the tumor and relevant clinical parameters were entered into univariate and multivariate survival analyses. RESULTS. At the end of the study, 49 patients (55. 1%) had died. The median overall survival was 5.7 years. Low methionine uptake was significantly favorable in the multivariate survival analysis (P = 0.04) along with oligodendroglioma (P = 0.003). In the histologic subgroups, C-11-methionine uptake was an important survival factor among patients with astrocytomas (P = 0.05) and oligodendrogliomas (P = 0.03). Tumor resection was a favorable prognostic factor in patients with high methionine uptake (P = 0.01) but not in patients with low uptake. CONCLUSIONS. Baseline C-11-methionine PET is a prognostic indicator in patients with low-grade gliomas. The results imply that PET is a valuable tool in the clinical management of these patients and may assist in the selection of patients for therapy. (C) 2001 American Cancer Society.