Risk Factors
While no one knows the exact causes of colorectal cancer, there are several known risk factors, including age and family history.
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Age
More than 90 percent of people with colorectal cancer are diagnosed after age 50.
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Family History
Close relatives of a person with a history of colorectal cancer are somewhat more likely to develop the disease, especially if the relative had the cancer at a young age.
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Personal History of Cancer
A person who has already had colorectal cancer may develop colorectal cancer a second time. Women with a history of cancer of the ovary, uterus or breast are also at a somewhat higher risk.
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Ulcerative Colitis or Crohn's Disease
A person who has a condition that causes inflammation of the colon for many years is at increased risk.
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Colorectal Polyps
Polyps are growths on the inner wall of the colon or rectum, common in people over age 50. Most polyps are benign, but some can become cancerous. Finding and removing polyps may reduce the risk of colorectal cancer.
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Diet
Diets that are high in fat and low in fiber are associated with an increased risk of colorectal cancer. Some studies suggest that diets high in red meats and processed meats may also increase risk.
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Obesity
Obesity and lack of exercise is linked to an increase risk of colorectal cancer.
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Cigarette Smoking
Frequent smokers may be at an increased risk of developing polyps and colorectal cancer.