The efficacy of
boron neutron capture therapy (BNCT) for the treatment of intracerebrally implanted rat
gliosarcomas was tested. Preferential accumulation of 10B in
tumors was achieved by continuous infusion of the
sulfhydryl borane dimer, Na4(10)B24H22S2, at a rate of 45-50 micrograms of 10B per g of
body weight per day from day 11 to day 14 after
tumor initiation (day 0). This infusion schedule resulted in average blood 10B concentrations of 35 micrograms/ml in a group of 12
gliosarcoma-bearing rats and 45 micrograms/ml in a group of 10 similar
gliosarcoma-bearing rats treated by BNCT. Estimated
tumor 10B levels in these two groups were 26 and 34 micrograms/g, respectively. On day 14,
boron-treated and non-
boron-treated rats were exposed to 5.0 or 7.5 MW.min of radiation from the Brookhaven Medical Research Reactor that yielded thermal neutron fluences of approximately 2.0 x 10(12) or approximately 3.0 x 10(12) n/cm2, respectively, in the
tumors. Untreated rats had a median postinitiation survival time of 21 days. Reactor radiation alone increased median postinitiation survival time to 26 (5.0 MW.min) or 28 (7.5 MW.min) days. The 12 rats that received 5 MW.min of BNCT had a median postinitiation survival time of 60 days. Two of these animals survived greater than 15 months. In the 7.5 MW.min group, the median survival time is not calculable since 6 of the 10 animals remain alive greater than 10 months after BNCT. The estimated radiation doses to
tumors in the two BNCT groups were 14.2 and 25.6 Gy equivalents, respectively. Similar
gliosarcoma-bearing rats treated with 15.0 or 22.5 Gy of 250-kilovolt peak x-rays had median survival times of only 26 or 31 days, respectively, after
tumor initiation.