Understanding risk factors for colorectal cancer
Important risk factors for colorectal cancer include family and personal health history, especially:
- Family history of colorectal cancer or hereditary colorectal cancer syndromes.
- 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. Most people with colorectal cancer are 50 or older.
- Lifestyle choices, particularly, a diet high in red meat and processed meat, lack of exercise, and smoking
- Excess alcohol consumption (more than 2 drinks a day for men or 1 drink a day for women).
- Being overweight or obese
- Having type 2 diabetes
The importance of screening
Screening is important for preventing colorectal cancer. Screening can find polyps, which are growths that can become cancer. These polyps can be removed before they turn into cancer, the ACS says. Screening can also find cancer early, when it is small, hasn't spread and is easier to treat.
People who have no other risk factors except advancing age should begin regular screening for colorectal cancer at age 45, according to the ACS and the U.S. Preventive Services Task Force (USPSTF). 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 45 years old and with average risk for colorectal cancer, the ACS and USPSTF recommend:
- A very sensitive guaiac fecal occult blood test (gFOBT) or fecal immunochemical test (FIT) every year, or
- A flexible sigmoidoscopy every 5 years (or every 10 years with yearly FIT stood test), or
- A colonoscopy every 10 years, or
- A CT colonography (virtual colonoscopy) every 5 years, or
- A stool DNA test every 3 years
You'll need a follow-up colonoscopy if you choose any test other than a colonoscopy and have an abnormal result.
The ACS recommends that you start testing at an earlier age or have more frequent screening if you have any of these risk factors:
- A family history of colorectal cancer or polyps. If your parent, sibling or child was diagnosed at a younger age than 60, or you have 2 immediate family members diagnosed at any age.
- A family history of hereditary colorectal cancer syndromes, such as familial adenomatous polyposis (FAP) or hereditary nonpolyposis colon cancer (HNPCC or Lynch syndrome).
- A personal history of colorectal cancer or adenomatous polyps.
- A personal history of chronic inflammatory bowel disease.
Description of screening tests
Flexible sigmoidoscopy. A slender, flexible, hollow, lighted tube with a small video camera on the end is put 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 cancer may turn into cancer over time. You are awake. No medicines are used for this test. This test is used less commonly in the U.S. You will do bowel preparation before the test to clear stool from your colon and rectum
Colonoscopy. Just as in the sigmoidoscopy, a slender, flexible, hollow, lighted tube is put through the rectum into the colon to look for polyps and cancers. But a colonoscope is longer and allows the healthcare 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 cancer, may turn into cancer over time. You will do bowel preparation before the test to clear stool from your colon and rectum. You will be given anesthesia to make you sleep during this test. You'll need someone to drive you home afterward. Some people might prefer one of the other screening tests, but if you choose any of the other tests and an abnormality is found, you will likely still need a colonoscopy.
CT colonography (virtual colonoscopy). This test uses CT scans to check the colon for polyps or masses. A copmuter uses the images to make a 3-D model of the colon. You are awake for this test. For virtual colonoscopy, nothing is put into your colon. But a small tube must be put into the rectum to pump air into the colon. The bowel preparation is the same as for a colonscopy.
Fecal occult blood test (FOBT). This test can find hidden blood in the stool. Small samples of stool are smeared on a card, and a chemical is added to look for a color change that means blood is present. Blood in the stool can be a sign of polyps or cancers.
Fecal immunochemical test (FIT). This test is a lot like the fecal occult blood test. But you don't have any limits on what you eat or the medicines you take before the test.
Stool DNA test. This test looks for blood and certain DNA changes that cancer or polyp cells can shed into the stool. For this test, an entire stool sample is collected and sent off to a lab for testing.
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, they will discuss treatment options with you. The main types of treatment for colorectal cancer are surgery, radiation therapy, chemotherapy, and targeted therapy. Depending on how advanced the cancer is (how much there is and where it is), treatments may be combined or used one after another.
Reducing your risk for colorectal cancer
You can reduce your risk for colorectal cancer. Here is what the ACS recommends:
- Get to and stay at a healthy weight. Ask your healthcare provider what a healthy weight is for you. They can help you reach your goal weight.
- Eat a healthy diet that includes plenty of fruits, vegetables, and whole grains. Limit how much red and processed meat you eat.
- If you smoke, quit.
- Limit how much alcohol you drink. It's best not to drink.
- Get regular exercise. Aim for at least 75 minutes of vigorous activity or 150 minutes of moderate physical activity a week.
This information is not intended as a substitute for professional health care. Always consult with a healthcare provider for advice concerning your health. Only your healthcare provider can do a thorough disease risk assessment or determine if you have colorectal cancer.