79 patients with 'pure' oligodendroglioma, 52% had adequate follow-up. Contrast enhancement and endothelial hyperplasia correlated with survival:
Median survival:
11 years w/o enhancement and 11 yrs w/o endothelial
Only 3 years w/enhancement and 3.5 yrs w/endothelial prolif
Conversely, nuclear atypia, necrosis, mitosis were not correlated with survival.

New Oligodendroglioma grading system developed:
Grade A - absence of endothelial hyperplasia, non-enhancing
Grade B - with endothlial hyperplasia and/or enhancing
Survival for Grade A: 89% at 5yrs/ 60% at 8 yrs
Survival for Grade B: 33% at 5yrs/ 15% at 8 yrs

Double-blind grading was concordant in 96% of cases.

DaumasDuport97
J Neurooncol 1997;34:61-78