Risk Factors

Polyps on the colon:

  • Particularly adenomatous polyps, are a risk factor for colon cancer. The removal of colon polyps at the time of colonoscopy reduces the subsequent risk of colon cancer.
  • Larger and those with greater surface area (villous polyps compared to tubular) are more likely to undergo neoplasia due to the greater likelyhood of one of these cells undergoing the series of malignant transformations into cancer.

History of cancer:

  • Individuals who have previously been diagnosed and treated for colon cancer are at risk for developing colon cancer in the future.
  • Women who have had cancer of the ovary, uterus, or breast are at higher risk of developing colorectal cancer.


  • Family history of colon cancer, especially in a close relative before the age of 55 or multiple relatives.
  • Familial adenomatous polyposis (FAP) carries a near 100% risk of developing colorectal cancer by the age of 40 if untreated
  • Hereditary nonpolyposis colorectal cancer (HNPCC) or Lynch syndrome


  • Smokers are more likely to die of colorectal cancer than nonsmokers. An American Cancer Society study found "Women who smoked were more than 40% more likely to die from colorectal cancer than women who never had smoked.
  • Male smokers had more than a 30% increase in risk of dying from the disease compared to men who never had smoked.


  • Studies show that a diet high in red meat and low in fresh fruit, vegetables, poultry and fish increases the risk of colorectal cancer.

Physical inactivity:

  • People who are physically active are at lower risk of developing colorectal cancer.

Inflammatory bowel disease:

  • About one percent of colorectal cancer patients have a history of chronic ulcerative colitis. The risk of developing colorectal cancer varies inversely with the age of onset of the colitis and directly with the extent of colonic involvement and the duration of active disease.
  • Patients with colorectal Crohn's disease have a more than average risk of colorectal cancer, but less than that of patients with ulcerative colitis.

Environmental factors:

  • Industrialized countries are at a relatively increased risk compared to less developed countries that traditionally had high-fiber/low-fat diets.