[Malignancy grading of glial tumors. I. Astrocytomas]

Abstract

A total of 91 fibrillar, protoplasmic and gemistocytic astrocytomas, 56 pilocytic astrocytomas and 70 glioblastomas, surgically obtained from 1973 to 1979, were evaluated. A four-grade malignancy system was applied to the astrocytomas. The grading criteria for the astrocytomas included quantitative cell density, cellular and nuclear polymorphism, mitotic activity, proliferative changes in the vascular elements and degree of necrosis. Using these criteria it was possible to distinguish four grades. Astrocytoma grades 1 and 2 correspond to the rubric "low-grade astrocytoma" in the English nomenclature, grades 3 and 4 to "high-grade astrocytoma". From the 91 fibrillar, protoplasmic and gemistocytic astrocytomas there were 12, 29, 31 and 19 tumors in grades 1 to 4 respectively. The corresponding distribution for the 56 pilocytic astrocytomas was 20, 29, 6, 1. Median survival for the fibrillar, protoplasmic and gemistocytic group for malignancy grades 1-4 were 43.8, 33.5, 8.4 and 5.6 months respectively. The corresponding figures for the pilocytic astrocytomas grades 1-3 were greater than 66, greater than 69, and 20.0 months.