Oligodendroglioma. A comparison of two grading systems.

In order to compare the grading system for oligodendrogliomas described by M.T. Smith (1983) with the conventional grading system according to Kernohan (1938), specimens from 72 patients were graded according to both systems, and survival times of the patients were compared. Survival rates decline in older patients. No interaction between the age of the patient and the degree of the tumor was found. No influence of localization of the tumor on survival was found. Similar to the system of Kernohan, the grading system of Smith distinguishes between only three groups of patients with significantly different survival times. In Smith's Grade A and Kernohan's Grade 1 the longest survivals are found; while in Smith's Grade D and Kernohan's Grade 4 the shortest survivals are found. Smith's Grades B and C as well as Kernohan's Grades 2 and 3 were intermediate with respect to the survival times of the patients and did not significantly differ from each other. With the independently significant features (cell density, pleomorphism, and necrosis) evaluated according to simple on-off scoring, and with the reduction from four grades to three, the grading system according to Smith would provide a simple and good, concise grading system for oligodendrogliomas of the brain.