Biodistribution of Boron Sulfhydryl (BSH) in Patients with Intracranial Tumors^*

Abstract

The therapeutic as well as the undesired effects of Boron Neutron Capture Therapy (BNCT) largely depends upon the absolute and relative ¹⁰B concentrations in tumors and in normal tissues and body fluids. Our present work on BSH in patients with intracranial neoplasms has been prompted by crucial questions regarding: tumor levels, tumor-to-normal tissue ratios, variations between different tumors, variations inside the same tumor, correlation between histology and ¹⁰B levels, time course of BSH uptake, pharmacokinetics of BSH, Temptative answers to some of these questions have been worked out for animals and experimental animal tumor models. For humans, Hatanaka et al. [2] have published boron concentrations measured at the time of re-operation and actual BNCT in 60 patients. Eleven to 17 hrs after intra-arterial or intravenous administration of 40 to 80 mg of ¹⁰B/kg as BSH, 26 glioblastoma patients yielded a median ¹⁰B concentration in the tumor of approximately 15 ppm and a median tumor-to-blood ratio of 1.1. In 13 cases of anaplastic astrocytomas the values were comparable with a median tumor concentration of approximately 22 ppm and a tumor-to-blood ratio of 1.4. In 4 cases of astrocytomas grade I-II, the median concentration dropped to around 5 ppm and the tumor-to-blood ratio remained always below 0.6. Beside Hatanaka’s findings, the literature contains only anecdotal data on the situation in humans [1,4,5].