Orthotopic implantation of colon carcinoma cells provides an experimental model in the rat that replicates the regional spreading pattern of human colorectal cancer

Our goal was to develop an experimental model of colon adenocarcinoma based on the orthotopic implantation of tumour cells in syngenic rats which would replicate the pattern of regional spreading of human colorectal adenocarcinoma. We used cell line DHD/K12-PROb and 62 BD-IX rats with intra-caecal injection of 1 x 10(6) cells. Macroscopic and histological examinations were made at different times after injection (from 1 to 16 weeks) with particular emphasis on caecal lesions and tumours were classified according to the TNM system (UICC, 1987). Our results suggest that this model provides a step-by-step reproduction of the development of human colorectal adenocarcinoma. It also allows us to predict how long it will take to achieve a certain degree of local spreading, which is essential for the design of cancer-related experiments. Moreover, our model has the advantage that it uses immunocompetent rats, which facilitates its application.