Prognostic significance of contrast-enhancing low-grade gliomas in adults and a review of the literature.

OBJECTIVES: Survival and tumor recurrence for patients with low-grade gliomas is heterogeneous, with reported survival and recurrence times varying by several months to years. The prognostic implications of a contrast-enhancing low-grade glioma remain less well understood. METHODS: We retrospectively reviewed all adult patients who underwent a craniotomy for a hemispheric low-grade glioma (WHO grade II) from 1996 to 2006 at a single institution. Multivariate proportional hazards regression analysis was used to identify independent associations with survival, recurrence and malignant degeneration. Furthermore, a review of the literature for all works on low-grade gliomas and contrast enhancement was conducted. RESULTS: One hundred eighty-nine patients (87 fibrillary astrocytomas, 89 oligodendrogliomas and 13 mixed gliomas) were available for analysis, with 64 (34%) and 125 (66%) contrast-enhancing and non-enhancing tumors, respectively. There were no significant differences in clinical and treatment-related variables between patients with and without contrast enhancement. After multivariate analysis, contrast enhancement was independently associated with decreased survival (p=0.006) and increased recurrence (p=0.04) and trended toward significance with malignant degeneration (p=0.15). Five-year overall survival, progression-free survival and malignancy-free survival rates for patients with enhancement versus patients without enhancement were 70 versus 85% (p=0.002), 32 versus 49% (p=0.008) and 74 versus 90% (p=0.002), respectively. The review of the literature identified 14 works that fit our criteria. The majority of these published works had design-related limitations including small population size as well as the inclusion of non-WHO grade II gliomas, pediatric patients and patient undergoing biopsy. DISCUSSION: This study may provide insights into risk stratifying patients with low-grade gliomas and most specifically those that contrast enhance.