Intraoperative Radiation Therapy for Glioblastoma — Indications and Treatment Results

Glioma, a neoplasm of neuroectodermal origin, is oncopathologically defined as carcinoma in the brain. The most poorly differentiated glioma, glioblastoma multiforme, usually grows in the deep white matter of cerebrum and rapid invasion in multiple directions along the white matter has already occurred by the time of diagnosis. Infiltrated tumor cells into the surrounding brain tissue were observed at least 2 cm apart from the margin of the enhanced tumor area on computed tomography (CT) scan (Burger et al. 1983). In advanced stages, the tumor infiltration in the white matter extends into the contralateral hemisphere, and finally to the brain stem or the cerebellum through the cerebral peduncle. On surgery for such an invasive glioblastoma, most cases are beyond the stage for desirable removal of tumors, because of the risk of damage to the normal function of surrounding brain tissue. With surgery alone followed by best conventional care, patients have a uniformly fatal course with a median survival of 17.0 weeks (Walker et al. 1978). The restriction of the surgical treatment has inevitably required postoperative radiation therapy, which has been the most important treatment modality following surgery.