BIODISTRIBUTION OF BORON SULFHYDRYL FOR BORON NEUTRON-CAPTURE THERAPYIN PATIENTS WITH INTRACRANIAL TUMORS

THE BIODISTRIBUTION OF boron sulfhydryl (BSH) was evaluated for baron neutron capture therapy of brain tumors. A selective boron delivery to the neoplasm is a prerequisite for successful therapy. The uptake of BSH after intravenous administration was analyzed in neoplastic and no rmal tissues in 61 patients undergoing craniotomies for intracranial t umors. The patients received 10 to 100 mg of BSH/kg (5-50 mg of B-10/k g) body weight, 2 to 72 hours before surgery. The tumor boron concentr ations ranged from 0.2 ppm (mu g/g) in a tow-grade glioma to 19.5 ppm in a high-grade glioma. The tumor to blood baron ratio rose above 1 in 15 of 24 high-grade intracerebral tumors, 18 h or more after BSH infu sion. The baron concentration in high-grade tumors was heterogeneous. Low-grade intracerebral tumors showed a low baron concentration with a tumor to blood ratio below 1. Extracerebral tumors, mainly meningioma s, showed boron concentrations comparable with high-grade tumors, with a tumor to blood ratio above 1 in 10 of 17 patients. The boron concen trations in skin and muscle compared roughly with the blood values. Bo ron did not enter normal brain in any significant amount. In high-grad e tumors, tumor to brain ratios were above 2. Low boron concentrations in normal brain make BSH safe for a Phase I normal tissue tolerance s tudy. Computed tomographic contrast enhancement was evaluated to tumor baron uptake for 30 patients. Tumor enhancement on computed tomograph y does not permit the prediction of individual tumor boron concentrati ons; however, the absence of a contrast enhancement was always associa ted with low boron uptake.