[PET/CT with 11C-methionine as a predictor of disease-free survival in patients with IDH1 wild type diffuse glioma]

Prognosis of IDH (IDHwt) wild-type gliomas is worse compared to IDH-mutant tumors regardless of histological criteria for glioblastoma. However, there is still uncertainty regarding favorable course of disease and predictors of long-term survival in IDHwt gliomas.

To study the metabolic characteristics of IDH1wt diffuse astrocytomas using ¹¹C-methionine PET/CT and prognostic significance of PET-associated parameters for disease-free survival.

We analyzed 79 adults with IDH1wt diffuse gliomas. Quantitative analysis consisted of ¹¹C-methionine accumulation index and metabolic tumor volume. Kaplan-Meier and Cox analyses were used to determine prognostic significance of histological findings and PET parameters.

Glioblastoma and astrocytoma grade 2 or 3 were diagnosed in 41% and 59% of patients, respectively. Accumulation index significantly differed between astrocytomas grade 2 and 3 (p=0.03). Significant predictors of disease-free survival were age, histological type of astrocytoma and tumor grade, contrast enhancement, PET-associated biomarkers (accumulation index and metabolic tumor volume) and compliance of metabolic pattern with glioblastoma syndrome (p<0.05). Disease-free survival >24 months was established for age <41 years, maximum accumulation index <1.64, tumor accumulation index <1.39 and metabolic tumor volume <13.44 cm³. In multivariate Cox analysis, independent predictors of disease-free survival were age and PET syndrome of glioblastoma.

Diffuse IDH1wt gliomas are a heterogeneous group differing in metabolic characteristics and prognosis. PET/CT with ¹¹C-methionine may be effective for stratifying patients into groups with unfavorable and favorable prognosis, as well as assessment of advisability of in-depth searching for IDH1/IDH2 mutation.