Although the molecular genetic changes that take place during carcinogenesis in the large bowel have been well elucidated, very little work has been done on the carcinogenesis process in the small bowel where this phenomenon is much rarer. The few studies that have been done to suggest that certain oncogenes, i.e., erbB2, K-ras, cyclin D1, and p53, are all altered in ways and in frequency similar to these phenomena in large bowel cancer. Some tumor markers have been noted to occur in malignant carcinoid tumours as well. Given the overall similarities in the epidemiology and the role of the adenoma-carcinoma sequence for both small bowel adenocarcinoma and colorectal adenocarcinoma, it is highly likely that the same molecular genetic changes play a major role. Further work is needed to confirm this. If true, a potentially important are of future research would be to determine why these molecular genetic changes occur so much less frequently in the small bowel as compared to the large bowel.