Early prognostic factors related to progression and malignant transformation of low-grade gliomas

Abstract

Objective: Low-grade gliomas (LGGs) are infiltrative tumors characterized by slow growth. However, during early period, LGGs can progress and transform into a malignant pathology. We analyzed the prognostic factors for progression and malignant transformation in LGGs.

Materials and methods: From 2000 to 2009, we operated on 86 patients: 42 oligodendrogliomas, 12 oligoastrocytomas, and 32 astrocytomas. The male:female ratio was 47:39, and the median age was 41 (±17.4) years. The mean follow-up period was 4.25 (±2.8) years. We analyzed the prognostic factors for progression-free survival (PFS), overall survival (OS), and malignant transformation, considering age, sex, KPS, clinical presentation, tumor location, radiologic pattern, extent of removal, pathologic subtype, and adjuvant treatment.

Results: In univariate analysis, non-eloquent location, gross total removal, and oligodendroglial pathology statistically correlated with improved PFS and OS. In multivariate analysis, gross total removal correlated with longer PFS (p=0.043), and gemistocytic astrocytoma had a poor PFS (p=0.004). Younger age and non-eloquent area showed an improved OS (p=0.002 and 0.041), and astrocytic pathology showed a poor OS (p=0.01). Malignant transformation was pathologically diagnosed in 13 out of 86 patients (15%). Gemistocytic astrocytoma correlated independently with malignant transformation (p=0.022).

Conclusion: In LGGs, extent of removal associated with tumor progression. The pathology of astrocytoma, especially gemistocytic astrocytoma, was an independent prognostic factor for recurrence and malignant transformation.