What are the risk factors for colorectal cancer?

Everyone is at some risk for colorectal cancer (cancer of the colon or rectum, both of which make up the large bowel). It affects men and women equally. In early stages of colorectal cancer there are often no symptoms, so regular screening is important.

The primary risk factor is age. More than 90 percent of colorectal cancer cases are in people over age 50. That's why all individuals should be screened at age 50 if they have not already done so.

You are at a higher risk and may need screening earlier if:

• You or someone in your family has had colorectal cancer or polyps
• You have inflammatory bowel disease (Crohn's disease or ulcerative colitis)
• You have a history of endometrial, ovarian, or breast cancer

Age - colorectal cancer is more likely to occur as people get older. Although this disease can occur at any age, most people who develop colorectal cancer are over age 50. Polyps - Polyps are abnormal growths that protrude from the inner wall of the colon or rectum. They are relatively common in people over age 50. Most polyps are benign (noncancerous), but experts believe that the majority of colorectal cancers develop in polyps known as adenomas. Detecting and removing these growths may help prevent colorectal cancer. The procedure to remove polyps is called a polypectomy. Personal history - a person who has already had colorectal cancer is at an increased risk of developing colorectal cancer a second time. Also, research studies have shown that some women with a history of ovarian, uterine, or breast cancer have a higher than average chance of developing colorectal cancer. Family history - Close relatives (parents, siblings, or children) of a person who has had colorectal cancer are somewhat more likely to develop this type of cancer themselves, especially if the family member developed the cancer at a young age. If many family members have had colorectal cancer, the chances increase even more. Ulcerative colitis or Crohn colitis - Ulcerative colitis is a condition that causes inflammation and sores (ulcers) in the lining of the colon. Crohn colitis (also called Crohn disease) causes chronic inflammation of the gastrointestinal tract, most often of the small intestine (the part of the digestive tract that is located between the stomach and the large intestine). People who have ulcerative colitis or Crohn colitis may be more likely to develop colorectal cancer than people who do not have these conditions. Diet - some evidence suggests that the development of colorectal cancer may be associated with high dietary consumption of red and processed meats and low consumption of whole grains, fruits, and vegetables. Researchers are exploring what role these and other dietary components play in the development of colorectal cancer.