Imaging growth and isocitrate dehydrogenase 1 mutation are independent predictors for diffuse low-grade gliomas

We explored whether spontaneous imaging tumor growth (estimated by the velocity of diametric expansion) and isocitrate dehydrogenase 1 (IDH1) mutation (estimated by IDH1 immunoexpression) were independent predictors of long-term outcomes of diffuse low-grade gliomas in adults. One hundred thirty-one adult patients with newly diagnosed supratentorial diffuse low-grade gliomas were retrospectively studied. Isocitrate dehydrogenase 1 mutations were present in 107 patients. The mean spontaneous velocity of diametric expansion was 5.40 +/- 5.46 mm/y. During follow-up (mean, 70 +/- 54.7 mo), 56 patients presented a malignant transformation and 23 died. The median malignant progression-free survival and the overall survival were significantly longer in cases of slow velocity of diametric expansion (149 and 198 mo, respectively) than in cases of fast velocity of diametric expansion (46 and 82 mo; P < .001 and P < .001, respectively) and in cases with IDH1 mutation (100 and 198 mo, respectively) than in cases without IDH1 mutation (72 mo and not reached; P = .028 and P = .001, respectively). In multivariate analyses, spontaneous velocity of diametric expansion and IDH1 mutation were independent prognostic factors for malignant progression-free survival (P < .001; hazard ratio, 4.23; 95% CI, 1.81-9.40 and P = .019; hazard ratio, 2.39; 95% CI, 1.19-4.66, respectively) and for overall survival (P < .001; hazard ratio, 26.3; 95% CI, 5.42-185.2 and P = .007; hazard ratio, 17.89; 95% CI, 2.15-200.1, respectively). The spontaneous velocity of diametric expansion and IDH1 mutation status are 2 independent prognostic values that should be obtained at the beginning of the management of diffuse low-grade gliomas in adults.