The 3 Main Types of Colon Cancer Screenings Explained

Dr. James Grant

| 3 min read

James D. Grant, M.D. is senior vice president and ch...

Turning 50 years old used to carry with it the distinction of achieving the age at which regular colon cancer screenings should occur. However, since rates of colon cancer among younger individuals have been increasing, the U.S. Preventive Services Task Force now recommends adults between the ages of 45 and 75 and with no symptoms receive regular colorectal cancer screening.

Why a screening test?

Screenings are tests that check a patient’s current condition, usually before there are any symptoms. Screenings are used to identify a baseline. Doctors can then use subsequent screening tests to compare, making it easier to find changes that might signal a concern.
For colon cancer, which is the fourth most commonly diagnosed cancer in the nation, regular screenings help to detect the cancer early, when it is highly treatable and potentially curable. Colon cancer screenings can save lives.
If a potential problem is found on a screening test, doctors will then recommend further testing to provide a diagnosis.

What are the three main types of screening tests?

There are three main types of screening tests for colorectal cancer:
  • Colonoscopy: Colonoscopies remain the “gold standard” for colon cancer screening because they are the most accurate way to detect colorectal cancers or other abnormalities of the colon and rectum. During a colonoscopy, a physician uses a camera on a flexible tube to examine the colon and rectum for any signs of change, such as irritation, swelling or abnormal growths called polyps. If a growth or lesion is found, it can be removed and sent to the lab for testing. The procedure does require patients to use a prep solution to thoroughly empty their bowels. This is so the doctor can clearly see details inside the area.

    If no abnormalities are detected after a first screening, and there are no symptoms or risk factors, you and your doctor will discuss when the next screening should occur.
  • Flexible sigmoidoscopy: Flexible sigmoidoscopy also uses a camera on a flexible tube to examine the colon and rectum, but it only looks at a small part of the colon. As a result, this is a less invasive procedure with a less complicated preparation process. However, because a flexible sigmoidoscopy does not look at the entire colon, physicians tend not to use the procedure for colon cancer screening. Flexible sigmoidoscopy is not a first nor ideal choice for colon cancer screening.
  • Stool tests: Three types of stool tests are currently available. The guaiac-based fecal occult blood test (gFOBT) and the fecal immunochemical test (FIT) detect blood in the stool, which can be a sign of colon cancer. If blood is detected, the individual will need a follow-up colonoscopy. These tests are completed yearly. The FIT-DNA test detects altered DNA in the stool. This type of test is completed every three years.

    Individuals use an at-home kit to obtain the stool sample, place it in a sealed container and send it off for testing. While stool tests are much less invasive and do not require any special bowel preparation, they are not as accurate and may return false-positive results.
Individuals who have a family or personal history of colorectal cancer, polyps, inflammatory bowel disease or certain genetic disorders may need to begin screenings earlier than age 45. Individuals should talk with their doctor about their symptoms and health history, and to come up with a plan for colon cancer screening.
James D. Grant, M.D., is senior vice president and chief medical officer at Blue Cross Blue Shield of Michigan. For more health tips and information, visit
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