[A model for sensitivity determination of anticancer agents against chemical-induced colon cancer in rats]

Chemically-induced colon cancer was used to test the sensitivity of tumors to chemotherapeutic agents. Thirty-four Sprague-Dawley rats received dimethylhydrazine (40 mg/kg) s.c. once weekly for 10 weeks to induce colon cancer. Twenty weeks after beginning the carcinogen treatment, a barium enema was performed to determine the size of colon tumors. The animals were divided into CDDP group and CPT-11 group, in which the maximum tolerable dose of each drug was given. After 5 weeks of treatment, the barium enema was repeated. "Response" was assessed on the basis of tumor doubling time. Response rates in the CDDP and CPT-11 groups were 6% and 35%, respectively. This reflects the clinical data of those drugs and confirms the results of our previous study. The present study may be a predictive model for screening anticancer drugs for human colorectal malignancy.