Abstract
Chemicaly-induced autochthonous colon cancer was used to examine the sensitivity of tumors to combined administration of cisplatin (CDDP) and UFT, a mixture of tegafur (1- ( 2-tetrahydrofuryl) -5-fluorouracil) and uracil. Thirty-four Sprague-Dawley rats received azoxymethane (7.4mg/kg) s. c. once weekly for 10 weeks to induce colon cancer. Twenty weeks after the start of carcinogen treatment, barium enemas were performed to visualize tumors. The animals were divided into three groups, which were subjected to the following treatments: group A, control; group B, UFT; and group C, UFT plus CDDP. After 5 weeks of treatment, barium enemas were repeated. A total of 92 tumors were found on necropsy, and the mean tumor incidence per rat was 4.4 in group A, 2.9 in group B, and 2.5 in group C. Tumor doubling times were available in 54 % (50/92) of tumors. The mean doubling time of 24 tumors in the control group was 19.0±8.4 (SD) days. Response was judged as effective when the doubling time exceeded 35.8 days, calculated from the mean + 2 SDs in the control group. The response rates in the UFT and the UFT plus CDDP groups were 25 % and 50 %, respectively. UFT in combination with CDDP showed synergistic antitumor effects in autochthonous colon cancer. The present autochthonous colon cancer system may be useful for the evaluation of single anticancer drugs and combined treatments.
