The exact causes of colorectal cancer are not known. However, studies show that the following risk factors increase a person’s chances of developing colorectal cancer:
- Age. Colorectal cancer is more likely to occur as people get older. This disease is more common in people over the age of 50. However, colorectal cancer can occur at younger ages, even, in rare cases, in the teens.
- Diet. Colorectal cancer seems to be associated with diets that are high in fat and calories and low in fiber. Researchers are exploring how these and other dietary factors play a role in the development of colorectal cancer.
- Polyps. Polyps are benign growths on the inner wall of the colon and rectum. They are fairly common in people over age 50. Some types of polyps increase a person’s risk of developing colorectal cancer. A rare, inherited condition, called familial polyposis, causes hundreds of polyps to form in the colon and rectum. Unless this condition is treated, familial polyposis is almost certain to lead to colorectal cancer.
- Personal medical history. Research shows that women with a history of cancer of the ovary, uterus, or breast have a somewhat increased chance of developing colorectal cancer. Also, a person who has already had colorectal cancer may develop this disease a second time.
- Family medical history. First-degree relatives (parents, siblings, children) of a person who has had colorectal cancer are somewhat more likely to develop this type of cancer themselves, especially if the relative had the cancer at a young age. If many family members have had colorectal cancer, the chances increase even more.
- Ulcerative colitis. Ulcerative colitis is a condition in which the lining of the colon becomes inflamed. Having this condition increases a person’s chance of developing colorectal cancer.
Having one or more of these risk factors does not guarantee that a person will develop colorectal cancer. It just increases the chances. People may want to talk with a doctor about these risk factors. The doctor may be able to suggest ways to reduce the chance of developing colorectal cancer and can plan an appropriate schedule for checkups.