Colorectal carcinoma is a term used to refer to cancerous growths of the colon, rectum and the appendix (1).
- cancer of the colon is more common when compared to rectal cancer
- in UK around two-thirds (64% in 2009) of all bowel cancers are cancers of the colon and over one-third (36%) are cancers of the rectum (including the anus) (2)
- in a high risk population, the ratio is 2:1 while the rates are similar in countries where the risk is lower
- majority of rectal cancer cases are seen in men while colon cancer cases are divided evenly between men and women (53%)
- ninety-five percent of malignant colorectal tumours are adenocarcinomas
Majority of colorectal cancers arise from adenomatous polyps most of which are benign but a few may develop into cancer overtime (1).
Most of the tumours are seen in the left side of colon. The percentage distribution of cases within the large bowel in Great Britain between the years 2007-2009 is as follows:
- 22% caecum and ascending colon
- 5% transverse colon
- 3% descending colon
- 20% sigmoid colon
- 7% rectosigmoid junction
- 27% rectum (2)
Much epidemiologic data for these two carcinomas have been grouped, but other aspects of the two diseases differ sufficiently that the two are discussed individually.