Clinicopathological Study of High-dose Fractionated Radiation Therapy in the Treatment of Glioblastoma

Twenty-six adults with glioblastoma multiforme (grade 4 astrocytoma) were postoperatively given high-dose fractionated radiation therapy (5 Gy twice weekly) with Linac X-rays. The results were compared with those in 26 patients treated by conventional fractionated radiation therapy (2 Gy 5 times weekly). The survival rates following treatment with high-dose fractionated radiation therapy and conventional fractionated radiation therapy were 65% vs. 65% at 1 year, 31% vs. 8% at 2 years, 14% vs. 4% at 3 years, and 4% vs. 0% at 5 years. The difference in length of survival between the two treatment groups was not statistically significant (p = 0.423). Autopsies were performed on 11 patients given high-dose radiation therapy and 13 who received conventional irradiation. In the high-dose group one patient had no residual tumor (vs. none in the conventional group) ; four had small residual tumors (vs. three) ; one had extensive coagulative necrosis of the tumor and surrounding brain tissue (vs. four) ; four had proliferative tumor growth (vs. four) ; and one had mixed glioblastoma and fibrosarcoma (vs. two). Complete cure may be possible in some cases, if extensive tumor removal is feasible and is followed by high-dose fractionated radiation therapy. The biological effect appears to be much greater with high-dose than with conventional fractionated radiation therapy. Therefore, in cases of tumor recurrence, a second course of radiation therapy must be undertaken cautiously.