Author(s): DaumasDuport C, Tucker ML, Kolles H, Cervera P, Beuvon F,
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Abstract This second part of our study of 'pure' oligodendrogliomas focuses on survival data analysis. In order to identify potentially useful prognostic factors and to assess the effectiveness of a new grading system, the 79 patients in the previously analyzed series for whom adequate follow-up could be obtained (52\%) were entered in the present analysis. Statistical analysis demonstrated that contrast enhancement and endothelial hyperplasia had powerful and similar influence on survival. Median survival with and without contrast enhancement were: 3 versus 11 years, and with or without endothelial hyperplasia were: 3.5 versus 11 years. Conversely, the degree of nuclear atypia and presence or absence of mitosis or necrosis were not correlated with survival. These findings allowed us to devise a simple grading system which discriminates two malignancy grades as follows: absence of endothelial hyperplasia and of contrast enhancement = Grade A, presence of endothelial hyperplasia and/or of contrast enhancement = Grade B. Of the 79 oligodendrogliomas in this study, 59 tumors were categorized as grade A and 20 as grade B. Median survival were: 11 years in grade A and 3.5 years in grade B. Five-year and 8-year survival rates were: 89\% and 60\% in grade A and: 33\% and 15\% in grade B. Double blind grading between two independent observers was concordant in 96\% of the cases. Application of this simple efficient and reproducible grading scheme should permit reliable comparison of retrospective or prospective therapeutic data emanating from various institutions.
This article was published in J Neurooncol
and referenced in Journal of Brain Tumors & Neurooncology