Colon Cancer Screening and Early Detection

A colonoscopy uses a small flexible tube with a light and a tiny camera to take a closer look at your colon. During a colonoscopy, your doctor will take pictures of the inside of the colon and may take tissue samples or remove polyps.

This type of colon cancer screening requires bowel prep beforehand, and you'll be asleep during the procedure. A colonoscopy is carried out every ten years in people with no risk factors for colon cancer.

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A sigmoidoscopy, including flexible sigmoidoscopy, uses a small tube, light and camera like a colonoscopy. However, sigmoidoscopy only looks at the rectum and bottom third of your colon, where colon cancers are more likely to occur.

Sigmoidoscopy is not a common choice for colon cancer screening in the United States because it doesn’t catch cancer higher up in the colon. It requires partial bowel prep and is done every five years.  

A virtual colonoscopy is an imaging test that uses CT technology to create images of the colon and look for abnormal spots, such as polyps or cancer. Like a colonoscopy, full bowel prep is still needed, but most people are awake during this imaging procedure. It’s done every five years.

You have a few options if you choose a stool-based colon cancer screening. With stool tests, you collect stool samples from the comfort of your home and then send the samples to a lab for testing. These tests detect signs of colon cancer through blood or DNA in the stool, but they are more likely to miss pre-cancerous polyps than a colonoscopy.   

Stool tests for colon cancer screening include:

• Guaiac-based fecal occult blood test (gFOBT): This type of fecal occult blood test is done yearly to detect hidden blood in the stool using a chemical reaction. Usually, you’ll need to collect multiple stool samples for this test and place them on a paper card. You must also follow diet and medication restrictions for a few days beforehand.
• Fecal immunochemical test (FIT): FIT also tests for hidden blood in the stool to help detect colon cancer. With FIT, you collect stool samples and place them in tubes filled with liquid before sending them to the lab. Unlike gFOBT, FIT doesn’t usually require you to make diet or medication changes beforehand.
• Stool DNA test: Along with hidden blood, a stool DNA test also looks for pieces of DNA in the stool that signal cancer or polyps. If you choose to do a stool DNA test, it’s typically done every three years.

A barium enema is a type of radiologic imaging procedure. During a double contrast barium enema, a liquid containing barium is injected through the rectum into the colon to coat the inside and the contrast is enhanced with the insufflation of air. Then, moving X-ray images, known as fluoroscopy, are taken to view the colon and look for signs of polyps or cancer.