Combined effects of low dose total body irradiation and biological response modifiers on C3H/He mouse murine tumor

Effects of combination of low dose total body irradiation (LDTBI) and BRM agent (OK432, Bestatin) using experimental murine tumor were studied. In addition, the effects as respect of LDTBI on tumor bearing mice and then tumor response of local irradiation combined with BRM agent (OK432, Bestatin) was investigated. They were evaluated by tumor growth delay time. Remarkable tumor growth delay was revealed in the group treated with LDTBI and BRM as compared with the group treated with LDTBI alone or BRM alone. TGT50/ x 3 value was 20.00±1.58 in cases of combination of LDTBI and OK432 and 16.27±0.63 in cases of radiation therapy alone. TGT50/ x 3 value applied for the evaluation of the data was defined as the time required for 50% of the tumors to grow into the 3 times as large volume as its initial volume. Dose modifying factor (D.M.F.) employing LDTBI and OK432 was 1.2 from correlation between radiation dose and TGT50/ x 3 value. D.M.F. was 1.28 employing LDTBI and Bestatin in a similar method. These results suggested that the combination of LDTBI and BRM may be useful in the cancer radiotherapy. The effector mechanism of LDTBI and BRM was also discussed. (author)