[Intraoperative radiation therapy for malignant glioma]

Intraoperative radiation therapy (IOR) is an ideal means of exterminating residual tumor after surgical resection. In this study, the clinical results of IOR using a Scanditronix Microtron MM-22 were evaluated in 14 patients with malignant glioma, five of whom had recurrent tumors. Between July, 1985 and October, 1986, 11 patients with glioblastoma multiforme (GB) were irradiated 18 times (mean, 1.6 times/case), and three with astrocytoma (Kernohan grade III) underwent IOR once each. The target-absorbed dose at 1 to 2 cm deeper than the tumor resection surface was 15 to 50 Gy. During irradiation, a cotton bolus was placed in the dead space after over 91% of the tumor had been resected. As a rule, external irradiation therapy was also given postoperatively at a dose of 30 to 52 Gy. One patient died of pneumonia and disseminated intravascular coagulation syndrome 1 month postoperatively. The 1- and 2-year survival rates of the remaining 13 patients were 84.6% and 61.5%, respectively; among the 10 with GB, they were 80% and 50%. Generally, the smaller the tumor size, the better the results. There were no adverse effects, despite the dose 15 to 50 Gy applied temporally to the tumor bed. IOR was especially effective against small, localized tumors, but was not always beneficial in cases of large tumors, particularly those with a contralateral focus. The improved survival rate in this series demonstrates that IOR is significantly effective in the "induction of remission" following surgical excision of malignant gliomas.