High dose radiation therapy in the treatment of malignant gliomas: Final Report

Abstract

One hundred patients with supratentorial malignant gliomas were prescribed to receive postoperative whole brain irradiation with doses ≥5000 rad; 41 had astrocytoma grade III and 59 had grade IV tumors. The median survival was 91 weeks for patients with grade III tumors and only 42 weeks for those with grade IV (p < 0.01). For both grades, patients who were ≤45 years of age survived significantly better than patients who were older at diagnosis (p < 0.05). Patients with tumors at each grade were divided into three groups depending on the total dose delivered to the tumor; 5000, 6000, 7500 rad (median doses). For patients with grade IV tumors the median survival was 30, 42 and 56 weeks respectively, these differences were significant (p < 0.05) between the extremes but not between consecutive dose groups and were maintained only up to 2 years from the initiation of treatment. For patients with grade III tumors, the median survival was 43, 82 and 204 weeks respectively; these differences were significant (p < 0.05) between consecutive dose groups and between extremes and were maintained up to 4 years from the initiation of treatment. For 22 patients with grade IV who were treated with high-doses (7500 rad), the median time for recurrence was 43 weeks while for six patients with grade III tumors it was 158 weeks. The use of higher radiation doses was well tolerated; it did not compromise the quality of survival, and did not yield normal brain tissue necrosis. However, these doses did not seem to alter the total survival of patients, nor did they seem capable of sterilizing these tumors. Histopathological changes that were observed in normal brain tissue that was irradiated with 7000–8000 rad suggest that increasing total doses beyond this range might attain tumor sterilization, but could also lead to frank radiation necrosis in these patients.