To explore the feasibility of employing
boron neutron capture therapy (BNCT) to treat liver
tumors, the effects of BNCT were investigated by using liver
tumor models and normal hepatocytes in mice. Liver
tumor models in C3H mice were developed by intrasplenic injection of SCCVII
tumor cells. After
borocaptate sodium (BSH) and boronophenylalanine (BPA) administration, (10)B concentrations were measured in
tumors and liver and the liver was irradiated with thermal neutrons. The effects of BNCT on the
tumor and normal hepatocytes were studied by using colony formation assay and micronucleus assay, respectively. To compare the effects of BSH-BNCT and BPA-BNCT, the compound
biological effectiveness (CBE) factor was determined. The CBE factors for BSH on the
tumor were 4.22 and 2.29 using D(10) and D(0) as endpoints, respectively. Those for BPA were 9.94 and 5.64. In the case of hepatocytes, the CBE factors for BSH and BPA were 0.94 and 4.25, respectively.
Tumor-to-liver ratios of
boron concentration following BSH and BPA administration were 0.3 and 2.8, respectively. Considering the accumulation ratios of (10)B, the therapeutic gain factors for BSH and BPA were 0.7 - 1.3 and 3.8 - 6.6, respectively. Therefore, it may be feasible to treat liver
tumors with BPA-BNCT.