Mixed gliomas. Their clinical course and results of surgery

43 cases of mixed gliomas (oligoastrocytomas) selected out of 505 supratentorial glial tumors were reviewed. 26 tumors were designated grade I and 17 as grade II. In 29 tumors two glial components occurred in about equal amounts whereas there was oligodendrocytes predominance in 11 cases and astrocytes preponderated only in 3 cases. 56% of the patients were male and 44% female. The mean age at the time of diagnosis was 45.6 years. There were 9 postoperative deaths and the result of surgery was poor in 6 cases. In the remaining 28 cases the immediate result was good or fair. There was a distinct tendency showed by the tumors with oligodendroglial cells predominance to involve the basal ganglia or contralateral hemisphere. As a corollary, these tumors had worse prognosis than the others. There was no difference in the result of surgery comparing grade I and II tumors. The average postoperative survival period was 47 months and the mean life span after the appearance of the first symptoms was 5.5 years. We failed to find the significance of divading tumors into grade I and II categories when applied to survival period.