Colorectal cancer

Risk Factors

Familial colorectal cancer syndromes:
  • Familial adenomatous polyposis (FAP)
    People with this syndrome typically develop hundreds of polyps in the colon and rectum. Cancer nearly always develops in one or more of these polyps between the ages of 30 and 50 if preventive surgery is not done.
  • Gardner's syndrome
    Gardner's Syndrome is an inherited condition that leads to the formation of multiple polyps throughout the intestinal tract. There is no specific treatment for this disease other than surgery to prevent the development of cancer. Fortunately, Gardner's Syndrome is quite rare. Polyps are growths that develop within the intestines. They are quite common and many people will have a few in the colon, especially as they get older. People with this disease, however, have many polyps (sometimes hundreds to thousands) and the polyps develop at an earlier age, usually by age 16. They may occur throughout their stomach, small intestine, and large intestine, and they have a high potential for becoming cancerous. There is no specific treatment other than close follow-up and surgery to prevent cancer. Any complications that may arise will need to be treated accordingly.
  • Hereditary nonpolyposis colon cancer (HNPCC)
    Develops in people at a relatively young age without first having many polyps. Women with this condition also have an increased risk of developing cancer of the endometrium (lining of the upper part of the uterus).
Personal history of colorectal cancer:
  • A personal history of intestinal polyps: Adenomatous polyps do increase the risk of colorectal cancer.
  • A personal history of chronic inflammatory bowel disease: Chronic inflammatory bowel disease increases the risk of developing colon cancer

90% of people found to have colorectal cancer are over 50 years old.

A diet mostly from animal sources:

A diet that consists mostly of foods that are high in fat, especially from animal sources, can increase the risk of colorectal cancer.


Beginning at age 50, both men and women should follow one of the three screening options below:

  • Yearly fecal occult blood test plus flexible sigmoidoscopy every 5 years*, or
  • Colonoscopy every 10 years*, or
  • Double contrast barium enema every 5-10 years*.

*A digital rectal examination (DRE) should be performed at the time of each screening sigmoidoscopy, colonoscopy or barium enema examination.

Yearly FOBT (fecal occult blood test)
Sensitivity ranges from 65% to 97% depending in the test used and position the tumour is located.


People should begin colorectal cancer screening earlier and/or undergo screening more often if they have any of the following colorectal cancer risk factors:

  • A strong family history of colorectal cancer or polyps (cancer or polyps in a first-degree relative younger than 60 or in two first-degree relatives of any age),
  • Families with hereditary colorectal cancer syndromes (familial adenomatous polyposis and hereditary non-polyposis colon cancer),
  • A personal history of colorectal cancer or adenomatous polyps, or
  • A personal history of chronic inflammatory bowel disease.