Effect of cancer chemotherapeutic drugs on the radiation-induced skin reactions in mouse feet.

The interactions of seven cancer chemotherapeutic drugs and radiation in normal skin were studied using the mouse foot skin scoring system. Single drug doses were administered 15 min before graded single doses of irradiation or at different intervals before and after a fixed radiation dose. Adriamycin (ADM), bleomycin (BLM), methotrexate (MTX), mitomycin-C (MM-C), and cis-platinum (cis-DDP) all significantly enhanced the radiation-induced skin reactions. The dose-effect factors (DEF) for these drugs ranged from 1.07 to 1.11. Cyclophosphamide (CTX) had a radioprotective effect (DEF 0.90), whereas 5-fluorouracil (5-FU) had no effect (DEF 1.00). The effect of ADM was present at administration from 6 h before to 2 min after irradiation, and the effect of BLM from 24 h before to 4 h after irradiation. The radioprotective effect of CTX and the enhanced effect of MM-C were only present on administration 15 min before and 2 min after irradiation. MTX and cis-DDP enhanced the skin reactions only when given before irradiation.