title: Oligodendrogliomas. Part II: A new grading system based on morphological and imaging criteria.
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.
authors.affiliation: Department of Pathology-Neurooncology, Hôpital Sainte-Anne, Paris, France.
authors.forename: C
authors.initials: C
authors.lastname: Daumas-Duport
authors.forename: M L
authors.initials: ML
authors.lastname: Tucker
authors.forename: H
authors.initials: H
authors.lastname: Kolles
authors.forename: P
authors.initials: P
authors.lastname: Cervera
authors.forename: F
authors.initials: F
authors.lastname: Beuvon
authors.forename: P
authors.initials: P
authors.lastname: Varlet
authors.forename: N
authors.initials: N
authors.lastname: Udo
authors.forename: M
authors.initials: M
authors.lastname: Koziak
authors.forename: J P
authors.initials: JP
authors.lastname: Chodkiewicz
mesh_terms: D001932:Brain Neoplasms / Q000145:classification* / Q000000981:diagnostic imaging / Q000401:mortality / Q000473:pathology*; D002455:Cell Division; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009837:Oligodendroglioma / Q000145:classification* / Q000000981:diagnostic imaging / Q000401:mortality / Q000473:pathology*; D012189:Retrospective Studies; D015996:Survival Rate; D013997:Time Factors; D014057:Tomography, X-Ray Computed