Intraoperative radiotherapy for intracranial malignancies. A pilot study.

Intraoperative radiotherapy (IOR) or "direct view" irradiation permits the delivery of a single exposure of high-energy electrons to a surgically exposed tumor. Surgical exposure permits physical retraction of normal uninvolved tissues away from the IOR beam as well as the accurate assessment of the target volume. IOR represents a "supplement" or "boost" dose to conventional fractionated external beam irradiation that is administered postoperatively. This pilot study represents the clinical experience in the US using IOR for brain tumors. At Howard University Hospital, Washington, DC, 12 patients underwent surgical resection or decompression and 1500 cGy were delivered to the tumor bed intraoperatively. After surgical recovery, 5000 cGy in 25 fractions were delivered to the whole brain and an additional 500 cGy cone-down boost were delivered to the tumor bed. This protocol was best tolerated when the cranial vault was decompressed. Two patients with meningioma are without evidence apparently NED at 8, 11, 12, and 15 months, respectively. A fifth patient died at 8 months NED from an accident. Three glioma patients died with disease at 3, 13, and 15 months, respectively. Two additional patients died 30 days after surgery. Indications, techniques, and clinical findings are presented.