Burkitt (who also described Burkitt's lymphoma), observed that colorectal cancer was rarer in Africa, than in th western world. He felt that this may have been due to the higher roughage diet in africans. Of note a low roughage diet may also contribute to the developement of appendicitis and diverticular disease.
The cause of colorectal cancer is not totally known. Certain conditions are known to increase the chances of developing colorectal cancer. These include the heridatry cancer syndromes such as Lynch syndrome (HNPCC ) and familial adenomatosis polyposis coli (FAP), adenomatous polyps, prolonged severe inflammation, previous gastrectomy, vagotomy and uretero-sigmoidostomy.
The recognition of the increased risk of colorectal cancer in patients who underwent implantation of the ureter into the sigmoid colon was one of the reasons that this procedure fell out of favour. An ileal conduit is the preferred option nowadays.
The best described chronic inflammation that causes colorectal cancer is ulcerative colitis. The longer the duration of inflammtion and the more extensive the segement of bowel involved the greater the chance of cancer. This is probably due to the ongoing cycle of injury and repair caused by chronic inflammation.