Colon and Rectal Cancers - Risk Factors

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Alcohol and Smoking. Alcohol use and smoking increase the risk for colorectal cancer. Patients who smoke and drink may also be diagnosed with colorectal cancer at a younger age than non-drinkers and non-smokers. Several studies suggest that women who smoke are at especially high risk of developing colorectal cancer.

Obesity. There is a demonstrated link between body mass and colon cancer risk for both men and women. The Centers for Disease Control and Prevention has reported that the risk of colon cancer rises as body mass index (BMI) increases. Obesity has been associated biologically with higher circulating levels of insulin and a hormone called insulin-like growth factor (IGF). Chronically high levels of these substances may increase colorectal cancer risk.

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Physical Inactivity. More than 50 studies from around the world suggest that physical activity helps prevent colon cancer. In contrast, exercise does not protect against rectal cancer.

Risk Factors for People with Inflammatory Bowel Disease

Crohn's disease and ulcerative colitis are chronic afflictions of the large intestine known as inflammatory bowel diseases (IBDs). Both have been linked to increased risk for colorectal cancer. (Patients with ulcerative colitis have a higher risk than those with Crohn's disease.) Family histories are helpful in determining risk associated with inflammatory bowel disease. Some studies suggest the following:

• Patients with IBD who have a family history of colorectal cancer face up to a five-fold risk of colon cancer themselves.
• Individuals without IBD who have relatives who suffered from both IBD and colorectal cancer may face a higher risk for developing colorectal cancer themselves.
• Individuals without IBD but with a family history of IBD and no colon cancer most likely face no higher risk for cancer themselves.