IDH mutation status trumps the Pignatti risk score as a prognostic marker in low-grade gliomas

Olatz Etxaniz, Cristina Carrato, Itziar de Aguirre, Cristina Queralt, Ana Muñoz, José L. Ramirez, Rafael Rosell, Salvador Villà, Rocio Diaz, Ana Estival, Pilar Teixidor, Alberto Indacochea, Sara Ahjal, Laia Vilà, Carme Balañá

Management of low-grade gliomas (LGG) is based on clinical and radiologic features, including the Pignatti prognostic scoring system, which classifies patients as low- or high-risk. To determine whether molecular data can offer advantages over these features, we have examined the prognostic impact of several molecular alterations in LGG. In a cohort of 58 patients with LGG, we have retrospectively analyzed clinical and molecular characteristics, including the Pignatti criteria, IDH mutations, TP53 mutations, the 1p/19q deletion, and MGMT methylation, and correlated our findings with progression-free survival (PFS) and overall survival (OS). Mean age of patients was 45 years; 71% were classified as low-risk by the Pignatti system. IDH mutations were detected in 62%, p53 mutations in 17%, the 1p/19q codeletion in 46%, and MGMT methylation in 40% of patients. Survival analyses were performed in the 49 patients without contrast enhancement. In the univariate analysis, IDH mutations, the 1p/19q codeletion, and the combination of IDH mutations with the 1p/19q codeletion were associated with both longer PFS (P = 0.006, P = 0.037, and P = 0.003, respectively) and longer OS (P < 0.001, P = 0.02, and P < 0.001, respectively). The multivariate analysis identified absence of IDH mutations as a factor for greater risk of progression [hazard ratio (HR) = 3.1; P = 0.007]and death (HR = 6.4; P < 0.001). We suggest that IDH mutations may be more effective than the Pignatti score in discriminating low- and high-risk patients with LGG.