Chemoprevention of development of colonic adenomatosis and carcinomatosis with 5-fluorouracil and ftorafur on animal model

Chemotherapy of Chemically-induced Colorectal Tumours

Benign and malignant tumours were induced in the large bowel of rats by the carcinogen 1,2-dimethylhydrazine (DMH). Benign tumours appeared from week 20 onwards and malignant tumours from week 30. 5-Fluorouracil was administered intraperitoneally in maximally tolerated doses from week 26 onwards and failed to influence significantly the development of either benign or malignant tumours. Tumours induced by DMH are a close model of human colorectal cancer and suitable for testing anticancer drugs. Agents with greater activity against colorectal cancer are required.

Inhibition of experimental colorectal cancer by razoxane (ICRF-159)

Large bowel cancer induced in rats by dimethylhydrazine (DMH) closely resembles human disease both histologically and clinically. In this study it has been used to assess the antimitotic drug razoxane (ICRF-159). Dimethylhydrazine induced benign colorectal tumours after 20 weeks and adenocarcinomas from 30 weeks. Razoxane was given from week 25 until the end of experiment (week 35) to see if this drug could inhibit the development of tumours. Animals were randomly allocated to four groups: DMH + razoxane (26), DMH + control (26), control + razoxane (25), control + control (25). There were fewer malignant colorectal tumours in rats receiving razoxane than in the controls (10 vs. 24; P = 0.04). Some animals developed malignant tumours of the small intestine as well as the large bowel and the number of malignant tumours for the whole intestinal tract was also reduced in animals receiving razoxane (15 vs. 32; P = 0.025). This study demonstrates inhibition of the development of malignant tumours in rats by razoxane. This finding may have relevance to colorectal cancer in man where razoxane has been used in disseminated disease and as an adjuvant to surgery.