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%)
- occurrence of colorectal cancer is strongly related to age, with almost
three-quarters of cases occurring in people aged 65 or over. Colorectal
cancer is the second most common cause of cancer death in the UK
- 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.
Around half of people diagnosed with colorectal cancer survive for at least
5 years after diagnosis (1).