Colorectal Cancer Screening

Topic Overview

Screening tests for colorectal (colon) cancer

Screening tests for colorectal cancer look for signs of cancer before you have symptoms. Screening tests for colorectal cancer include:

• Stool tests that can be done at home. They include:
  • FIT (fecal immunochemical test). This test checks for signs of blood in small samples of stool. There are no special diets to follow. This test is done every year.
  • FOBT (fecal occult blood test). It checks for signs of blood in small samples of stool. You will need to avoid certain foods and medicines before doing this test. This test is done every year.
  • sDNA (stool DNA/Cologuard). It checks for signs of blood and gene changes in an entire stool sample. This test is done every 3 years.
• Procedures that allow your doctor to look directly at your colon. These tests are usually done in a medical clinic or a hospital. They are done less often than stool tests but require more preparation. Getting ready may include having a liquid diet for a day or two before your appointment and following instructions to clean out your colon. These procedures include:
  • Colonoscopy. This test lets your doctor look at the inside of your entire colon. It is done every 10 years.
  • Sigmoidoscopy. It lets your doctor look at the inside of the lower part of your colon. It is done every 5 years. (Or you can have the test every 10 years if you also do the FIT every year.)
  • CT colonography, or virtual colonoscopy. This test uses pictures taken during a CT scan to look at your colon. This test is done every 5 years.

Colorectal Cancer: Which Screening Test Should I Have?

There is another screening test called the SEPT9 DNA test. It is a blood test that looks for a change in the SEPT9 gene. This gene change can be found in some people who have colorectal cancer. But this test doesn't work well to find polyps before they become cancer. And it has a higher rate of false-positive results than other screening tests. If the test finds a change in the gene, you will need a follow-up colonoscopy.

For people at an average risk for colorectal cancer

The U.S. Preventive Services Task Force (USPSTF) has the following advice for colorectal cancer testing:^{footnote 1}

• People ages 50 to 75 should have a screening test starting at age 50.
• People ages 76 to 85 can work with their doctors to decide if screening is a good option.
• People ages 86 and older are advised that screening for colorectal cancer is usually not helpful.

The American Cancer Society (ACS), the U.S. Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology recommend routine testing for people age 50 and older who have a normal risk for colon cancer.^{footnote 2}

Talk with your doctor about which test is best for you.

Experts agree that people with a higher risk, such as those who have a strong family history of colon cancer, may need to be tested sooner. Talk to your doctor about when you should be tested.

For people at an increased risk for colorectal cancer

Colonoscopy is the recommended screening test for people at high risk. Your doctor may recommend earlier or more frequent testing if you:

• Already have been diagnosed with colorectal cancer.
• Have a first-degree relative (parent, brother, sister, or child) with an adenomatous polyp or colorectal cancer.
• Have had adenomatous polyps removed from your colon. This type of polyp is more likely to turn into cancer, but the risk is still very low.
• Have inflammatory bowel disease, such as ulcerative colitis or Crohn's disease.
• Have a rare inherited polyp syndrome, such as FAP or Lynch syndrome (HNPCC).
• Have had radiation treatments to the abdomen or pelvis.