Most colorectal cancers develop from polyps, but there are also other risk factors that increase the likelihood of developing cancer. Dr. Jerman, can you tell us about some of these other risk factors?
Absolutely, Major Spencer. Age is a significant risk factor. In fact, 93 percent of colorectal cancer cases occur in people over the age of 50. For this reason, current recommendations are to begin screening at age 50 if there are no other risk factors.
Family history is another risk factor. A person who has two or more first-degree relatives with colorectal cancer, or any first-degree relatives diagnosed under the age of 60, has a three to six times higher risk of developing colorectal cancer themselves.
Race can also be a risk factor. African Americans have a higher risk of developing colorectal cancers than other races, and many providers recommend a screening colonoscopy in this group beginning at 45 years of age, rather than 50.
Finally, personal history has an effect on the likelihood of developing colorectal cancer. People who have previously had precancerous colon polyps, called adenomas, or actual colon cancer are at increased risk of developing additional precancerous polyps and recurrent colon cancer. In addition, men and women who have had other types of cancers, either in themselves or members of their family, may be at increased risk for colorectal cancer. Types of cancer that increase this risk include:
- Endometrial cancer
- Ovarian cancer
- Urinary tract or bladder cancer
- Stomach cancer
- Small intestine cancer
- Gallbladder or bile duct cancer
- Pancreatic cancer, and
- Certain brain cancers