Understanding Risk Factors for Colorectal Cancer
Important risk factors for colorectal cancer include family and personal medical history, especially:
- Family history of colorectal cancer or hereditary colorectal cancer syndromes. Up to 10 percent of people with colorectal cancer have inherited a genetic abnormality tied to this illness.
- Personal history of adenomatous polyps or chronic inflammatory bowel disease. Adenomatous polyps of the colon or rectum are noncancerous growths that may develop into cancer if not treated. Chronic inflammatory bowel disease includes ulcerative colitis and Crohn's disease.
Other factors that increase the risk for colorectal cancer, according to the ACS:
- Being of African-American or Eastern European Jewish descent
- Advancing age: More than 90 percent of people with colorectal cancer are 50 or older.
- Lifestyle choices, particularly, a diet high in fat from animal sources (red meat, processed meat), lack of exercise, and smoking
- Excess alcohol consumption (more than two drinks a day for men and one drink a day for women): Excess alcohol intake independently increases risk; excess alcohol may interfere with folic acid intake, and it may interfere with folate metabolism in the body.
- Obesity, which increases your risk for colorectal cancer
- Having type 2 diabetes, which may also increase your risk
The Importance of Screening
Screening is important for preventing colorectal cancer. Screening can find polyps (growths that can become cancer) and remove them before they turn into cancer, the ACS says. Screening can also find cancer early, when it is highly curable
People who have no other risk factors except advancing age should begin regular screening for colorectal cancer at age 50, according to the ACS and the U.S. Preventive Services Task Force. If you have a family history or other risk factors for colorectal cancer, talk with your health care provider about the need for screening at an earlier age or for more frequent screening. Several screening tests are available, but medical experts differ on which test is better or how often to get screened.
For those who are at least 50 years old and of average risk for colorectal cancer, the ACS recommends:
- A fecal occult blood test (FOBT) or fecal immunochemical test (FIT) every year, or
- A flexible sigmoidoscopy every five years, or
- A double-contract barium enema every five years, or
- A colonoscopy every 10 years, or
- A CT colonography (virtual colonoscopy) every five years, or
- A stool DNA test (best interval uncertain)
The ACS recommends that you begin testing at an earlier age or have more frequent screening if you have any of these risk factors:
- A family history of colorectal cancer. If your parent, sibling or child was diagnosed younger than 60, or you have two family members diagnosed at any age.
- A family history of hereditary colorectal cancer syndromes (familial adenomatous polyposis and hereditary nonpolyposis colon cancer).
- A personal history of colorectal cancer or adenomatous polyps.
- A personal history of chronic inflammatory bowel disease.
Description of screening tests
Fecal occult blood test (FOBT). This test can find hidden blood in the feces; blood can indicate the presence of polyps or cancers.
Fecal immunochemical test (FIT). This test is similar to a fecal occult blood test, but it doesn't require any restrictions on diet or medications before the test.
Flexible sigmoidoscopy. A slender, flexible, hollow, lighted tube is inserted through the rectum into the lower part of the colon to look for polyps and cancers. Any small polyp found may be removed; polyps, even those that aren't cancerous, eventually may turn into cancer. Recent research has indicated that this test may not be as effective in women. If you are a woman, talk with your health care provider about having a colonoscopy instead of a sigmoidoscopy.
Colonoscopy. Just as in the sigmoidoscopy, a slender, flexible, hollow, lighted tube is inserted through the rectum into the colon to look for polyps and cancers, but a colonoscope is longer and allows the health care provider to see the entire length of the colon. If a small polyp is found, your provider may remove it; polyps, even those that are not cancerous, eventually may turn into cancer.
Double-contrast barium enema. Barium sulfate, a chalky substance, is used to partially fill and open up the colon. An X-ray of the abdomen shows strictures (narrowed areas), obstructions (blockages), and other problems. If problems are seen, a colonoscopy will be needed to examine them further.
CT colonography (virtual colonoscopy). This test uses computerized tomography (CT) to examine the colon for polyps or masses using special technology. The images are processed by a computer to make a three-dimensional (3-D) model of the colon. Virtual colonoscopy is noninvasive, although it requires a small tube to be inserted into the rectum to pump air into the colon.
Stool DNA (sDNA). This test can be used to check the stool or fecal matter for specific changes in DNA (the genetic blueprint of each cell) that indicate signs of colorectal cancer. You must save an entire bowel movement and send the sample to a laboratory.
Treatment for Colon Polyps and Colorectal Cancer
If your health care provider finds a precancerous polyp, it can be removed during a colonoscopy. If your provider finds cancer, he or she will recommend one of several treatment options. The three main types of treatment for colorectal cancer are surgery, radiation therapy, and chemotherapy, the ACS says. A newer treatment available is called monoclonal antibodies; this treatment more specifically targets the cancer. Depending on how advanced the cancer is, treatments may be combined or used one after another.
Reducing Your Risk of Colorectal Cancer
You can reduce your risk for colorectal cancer by maintaining a healthy weight and eating a nutritious diet that includes plenty of fruits, vegetables, and whole grains. You should also limit how many high-fat foods you eat. You should quit smoking if you smoke and limit your alcohol consumption. You should also get regular exercise; the ACS recommends at least 30 minutes of moderate physical activity five or more days a week. Boosting your amount of exercise to 45 minutes five or more days a week can further reduce your risk for colorectal cancer.
This information is not intended as a substitute for professional health care. Always consult with a health care provider for advice concerning your health. Only your health care provider can do a thorough disease risk assessment or determine if you have colorectal cancer.