Experimental model of colon cancer

The liver is the most frequent site of metastases in colon cancer. No good animal model has been available to help improve the treatment of liver metastases or their prevention after resection of a primary colon cancer. The aim of this study was to develop a model of colon cancer induced by azoxymethane in the rat and to study the outcome after surgical resection alone or in association with intraperitoneal chemotherapy (5-fluorouracil (5-FU). Three hundred male Wistar rats received subcutaneous azoxymethane (10 mg/kg body weight/week) for 12 weeks. Eighty-three rats with isolated colon cancer underwent total colectomy; 40 of these rats with no metastases were randomized into two groups: surgery alone or surgery plus 5-FU (5 mg/kg body weight/day) for 5 days after surgery. Thirty rats were able to be evaluated. At autopsy, peritoneal carcinomatosis and liver metastases were more frequent in the control group than after adjuvant treatment with 5-FU (27.7 percent vs. 0, P less than 0.05; and 22.2 percent vs. 0, P less than 0.05, respectively). The rates of peritoneal and hepatic recurrence after resection of the primary cancer indicate that the model mimics the natural history of human colon cancer. In this model, 5-FU reduced the rate of peritoneal carcinomatosis and liver metastases but did not influence survival.