Oligodendrogliomas. Part II: A new grading system based on morphological and imaging criteria

J Neurooncol. 1997 Aug;34(1):61-78. doi: 10.1023/a:1005759220434.


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.

MeSH terms

  • Brain Neoplasms / classification*
  • Brain Neoplasms / diagnostic imaging
  • Brain Neoplasms / mortality
  • Brain Neoplasms / pathology*
  • Cell Division
  • Chi-Square Distribution
  • Female
  • Humans
  • Magnetic Resonance Imaging
  • Male
  • Oligodendroglioma / classification*
  • Oligodendroglioma / diagnostic imaging
  • Oligodendroglioma / mortality
  • Oligodendroglioma / pathology*
  • Retrospective Studies
  • Survival Rate
  • Time Factors
  • Tomography, X-Ray Computed