Colo-rectal cancer is a malignant neoplasm that affects the layer, lower portion of the intestinal tract. Also called colon cancer or bowel cancer, includes cancerous growth in the colon, rectum and appendix. It is the third most common form of cancer and the second leading cause of cancer related death in the western countries.
2/3 of Colo-rectal cancer occurs in the colon, sigmoid colon.
1/3 of Colo-rectal cancer occur in the rectum or at the recto sigmoid colon (junction)
- Colo-rectal cancer has recently declined among white person in the US.
- 50% higher, arising among African, Americans.
- Hispanics – one half the mortality rate of non-Hispanic white persons.
- Age after 50 years.
- Family history of Colo-rectal cancer.
- Chronic inflammatory bowel disease.
- Benign polyp, edematous polyps.
- Physical inactivity.
- A diet high in fat.
- Energy intake greater than requirement.
- Low vegetable fiber intake.
- High content of refined carbohydrate.
- Smoking (40%)
- High intake of red meat, low selenium.
- Decreased intake of protective micro nutrients.
- Physical inactivity, virus (Human Papilloma Virus).
Note: Diet likely contributes to risk in these sporadic cancers, although causality is not proved; above diets may promote mucosal exposure to bile acids and bacterial degradative by products.
Genes, some genes that signal a hereditary predisposition to colon cancer have been identified. For e.g. mutation in either of 2 genes MSHZ and MLHI can predispose a person to HHPCC.
Alcohol intake (heavy alcohol) use may also increase the risk of Colo-rectal cancer (NCI). One study found that “people, who drink more than 30 grams of alcohol per day and especially those who drink more than 4.5 gm per day, appear to have slightly higher risk of Colo-rectal cancer.