A model for sensitivity determination of anticancer agents against chemically-induced colon cancer in rats.

Chemically-induced colon cancer was used to test the sensitivity of tumors to chemotherapeutic agents. Seventy-one Sprague-Dawley rats received dimethylhydrazine (20mg/kg) s.c. once weekly for 20 weeks to induce colon cancer. Then a barium enema was performed to see the size of colon tumors. The animals were divided into three groups that were subjected to the following treatments: 5-fluorouracil (5 FU); 1-(2-tetrahydrofuryl)-5 FU(FT); and a mixture of FT and uracil (UFT). After 5 weeks of treatment, the barium enema was repeated. "Response" was assessed on the basis of tumor doubling time. Response rates in the 5-FU, FT, and UFT groups were 25%, 33% and 36%, respectively and this reflects the clinical data of these drugs. The present system may be a predictive model for screening anticancer drugs for human colorectal cancer.