The clinical and prognostic relevance of grading in intracranial ependymomas

Abstract

The clinical relevance of grading in ependymomas is almost always regarded as controversial. According to the classification of brain tumours revised by the World Health Organization (WHO) in 1993, brain tumours of ependymal origin are differentiated as subependymomas Grade I, ependymomas Grade II, and anaplastic (malignant) ependymomas Grade III. The purpose of the present retrospective study of 126 patients with intracranial ependymomas was to assess the clinical and prognostic significance of the topical classification and grading system by a uni- and multivariate statistical analysis. 87 Grade II ependymomas were predominantly located in the midline and in the fourth ventricle, whereas 39 anaplastic ependymomas Grade III were most often found in the cerebral hemispheres. Excluding the localization-linked operative mortality, progression-free survival (PFS) was significantly dependent on the histological grading. Median PFS time was 7.5 years in Grade II, but only 1.5 years in Grade III ependymomas. Stratifying for the two time intervals 1951-1970 and 1971-1990, and excluding the operative mortality, a multivariate Cox' model analysis of the covariates age, localization, grading, extent of surgery, and radiation therapy revealed that only the histological grading and radiation therapy had a significant impact on PFS. Thus, the WHO grading system has a statistically significant relevance for the long-term prognosis of intracranial ependymomas. However, the therapeutic management including radical tumour resection and additional local irradiation should be independent of the grading.

• Key Words: Classification, Ependymoma, Glioma, Grading, Prognosis, World Health Organization (WHO).