Risk Factors
No one knows exactly what causes colorectal cancer, but a number of risk factors have been identified. These include:

• Age. About 90% of people diagnosed with colon cancer are over age 50.
• Genetics. Genetic syndromes cause 5-10% of all colon cancers.
• Family history of colorectal cancer. About 20-25% of colorectal cancers occur among people who have a family (parent, sibling, or child) history of the disease.
• Personal history of colorectal cancer. Someone who has had colorectal cancer or adenomatous polyps has a higher risk of having the disease in the future.
• Lifestyle issues. Excessive consumption of red meat and alcohol, smoking, obesity, , diet low in fiber-rich vegetables, high-fat diet, and physical inactivity increase the risk of colorectal cancer. Among these, obesity has been shown to be the greatest risk factor for women.
• Race. In the US, African Americans have the highest incidence of and mortality from colorectal disease of any race or ethnic group.
• Diabetes. People with diabetes and insulin resistance have an increased risk of colorectal cancer.
• Acromegaly. An uncommon growth hormone disorder, acromegaly increases the risk of colorectal cancer.
• Radiation therapy. Radiation directed at the abdomen to treat previous cancers may increase the chances of getting colorectal cancer.
• Inflammatory bowel disease. This includes long-standing ulcerative colitis and extensive Crohn's disease of the colon.

More on this topic

Colorectal Cancer Screening (VIDEO)
Colorectal Cancer
Colon Anatomy & Function
What Is Colorectal Cancer
Tumor Growth
Cancer Staging
Signs & Symptoms
Screening & Diagnosis
A Less Invasive Look
Treating Colorectal Cancer
Detecting Cancer Recurrence
Preventing Cancer

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Breast Cancer, Cancer Introduction, Colorectal Cancer, Prostate Cancer