[Fractionated radiation and thermal-radiation actions on transplantable tumors]

The paper is concerned with the results of fractionated thermal-radiation action on Brown-Pearce tumor in rabbits, sarcoma-37 (C-37) and Lewis carcinoma (LLC) in outbred and hybrid F1 (C57B1/6 x CBA) mice. Rabbit tumors were subjected to hyperthermia on UHF Plot units 4 h after irradiation, and in mice with a water-bath directly before irradiation. The frequency of Brown-Pearce tumor regression was increased as a result of hyperthermia in 4 h. The comparison of the effectiveness of fractionated radiation or thermal-radiation action on murine tumors (2 of 3 fractions for 4 days) indicated different type changes of the value of the coefficient of thermal enhancement of hyperthermia. For C-37 it was decreased with an increase in the number of fractions, for LLC it was increased, probably as a result of reoxygenation and high radiosensitivity of C-37.