Colon Cancer Risk

Risk Factors

There are two risk groups for colorectal cancer: average and high-risk.

High-risk groups include those with either a personal or a family history of colorectal neoplasia (cancer or polyps), individuals with a long-standing history of inflammatory bowel disease, and people with familial colorectal cancer syndromes. Some of those at high risk may have a 100 percent chance of developing colorectal cancer.

All others are considered to be of average risk. In the average- risk individual, your risk increases throughout your life; 90 percent of colorectal cancers occur after age 50. When average-risk patients develop colorectal cancer, their cancer is considered to be sporadic (non-inherited).

The exact cause of colon cancer is unknown but it appears to be influenced both by hereditary and environmental factors.

Specific risk factors include:

• Personal History: A personal history of colorectal cancer, benign colorectal polyps which are adenomas, or chronic inflammatory bowel disease (e.g., ulcerative colitis and Crohn's disease) puts you at increased risk for colorectal cancer. In fact, people who have had colorectal cancer are more likely to develop new cancers in other areas of the colon and rectum, despite previous removal of cancer.
• Heredity: If one of your parents, siblings or children has had colorectal cancer or a benign adenoma, you have a higher risk of developing colorectal cancer. If two or more close relatives have had the disease, you also have an increased risk; approximately 20 percent of all people with colorectal cancer fall into this category. Your risk is even greater if your relatives were affected before age 60.
• Additionally, there are two genetic conditions, familial adenomatous polyposis (FAP) and hereditary nonpolyposis colorectal cancer (HNPCC), which lead to colorectal cancer in about five to 10 percent of patients.
• Familial adenomatous polyposis (FAP) . People who have inherited the FAP syndrome may develop hundreds to thousands of polyps in their colon and rectum at a young age, usually between ages five and 40. These polyps are all adenomas. By age 40, almost all patients with FAP will develop colon cancer if they don't have preventative surgery. Most people who have this syndrome begin annual colon examinations while in elementary school, and many choose to have their colon and rectum removed before cancer develops. FAP is rare, accounting for about one percent of all cases of colorectal cancer.
• Hereditary non-polyposis colon cancer (HNPCC) . Also known as Lynch Syndrome, HNPCC is a more common form of inherited colon cancer, accounting for about three to four percent of all colorectal cancer cases. While it is not associated with thousands of polyps, polyps are present and grow more quickly into cancer than in patients without HNPCC. Colon cancer in people with HNPCC also develops at a younger age than sporadic colon cancer, although not as young as in those with FAP.
• People with HNPCC often develop cancer in their 40s and 50s. Cancers in patients with HNPCC tend to be fast growing; occur more frequently in the right colon; and respond less to chemotherapy. About 70 percent of those with HNPCC will develop colorectal cancer by the age of 65.
• People with HNPCC often develop cancer in their 40s and 50s. Cancers in patients with HNPCC tend to be fast growing; occur more frequently in the right colon; and respond less to chemotherapy. About 70 percent of those with HNPCC will develop colorectal cancer by the age of 65.
• If you have a history of adenomas or colon cancer, or suspect you have a family history of the disease, you should discuss this with your health care professional. In some cases, you may wish to undergo genetic testing
• Race: African Americans are more likely to get colorectal cancer than any other ethnic group. Compared to Caucasians, African Americans are 10 percent more likely to develop colorectal cancer. Unfortunately, they also are more likely to be diagnosed in advanced stages. As a result, African Americans are 40 percent more likely to die from the disease than Caucasians.
• Diet: Eating a diet high in processed foods and red meats, refined grains, sweets and desserts may increase your risk of developing the disease. However, avoiding red meat and eating a low-fat diet rich in vegetables, fruit and fiber (e.g., broccoli, whole wheat bread and beans) may reduce your risk of developing colorectal cancer. Some studies suggest that getting an adequate supply of calcium and folic acid decreases the risk of colorectal cancer. Additionally, one study found that drinking eight to 10 glasses of water a day could reduce the risk of colorectal cancer by 40 percent. When it comes to alcohol, however, limit your consumption to no more than four drinks per week.
• Lifestyle: Regular exercise is a key weapon in the fight against colorectal cancer. Another significant risk factor in colorectal cancer is smoking. Get help quitting if you can't do it on your own.