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

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.

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.

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).

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.