The therapeutic effect of fractionated radiation on DMBA-induced hamster buccal pouch squamous cell carcinomas.

Seventy hamsters were divided equally into experimental groups A and B and control groups C-G. After treating the pouches of groups A and B animals with DMBA (thrice a week) for 14 weeks, the heads of the animals received fractionated radiation of a total dose of 21Gy and 42Gy, respectively. The untreated pouches of groups C and D animals were similarly irradiated. The pouches of groups E and F animals were treated with DMBA or mineral oil for 14 weeks, respectively. The pouches of group G animals remained untreated throughout the experiment. Radiation response (RR) was not noted for 12 exophytic tumors of group A; the remaining 43 tumors showed partial response. For group B, no RR was noted for four exophytic lesions; the remaining 28 lesions revealed a combination of partial and complete response. No endophytic lesions of group A showed RR; a significant increase in radiation response was noted for group B compared with group A. In conclusion, the hamster pouch oral cancer model could be employed to study the effect of fractionated radiation.