Colorectal Cancer Screening: Your Options Explained

This page is for adults thinking about colorectal cancer screening. It explains when to start, the main test options, and what a positive result means.

Colorectal cancer screening means checking for cancer — and for growths that could become cancer — before you have any symptoms. It is one of the most powerful kinds of screening we have, because it can do more than catch cancer early. It can actually help prevent it.

Here is why. Most colorectal cancers start as a small growth called a polyp on the inner lining of the colon or rectum. Certain polyps can slowly turn into cancer over years. Some screening tests can find and remove those polyps before they ever become dangerous.

Some colorectal screening can prevent cancer, not just find it early. Those are the tests that let a clinician see and remove precancerous polyps. Stool tests work differently. They flag people who then need a colonoscopy, and that colonoscopy is what removes anything found.

Most expert groups, including the U.S. Preventive Services Task Force, now recommend that people at average risk begin regular screening at age 45.

• Screening generally continues to age 75.
• For ages 76 to 85, whether to keep screening is an individual decision based on your overall health, life expectancy, and past screening results.

Some people should start earlier or screen more often. These include people with a family history of colorectal cancer, certain inherited conditions such as Lynch syndrome, a personal history of advanced polyps, or inflammatory bowel disease.

Age 45 is the usual starting point for average-risk adults — but higher-risk people may need to start sooner.

There is no single right test for everyone. Here is how the main options compare:

• Stool tests (FIT, gFOBT, stool DNA). (How FIT and stool DNA tests compare.) Done at home, no prep, no sedation. Must be repeated often — every 1 to 3 years depending on the test. A positive result leads to a colonoscopy.
• Colonoscopy. Examines the whole colon and can remove polyps in the same visit. Needs a full bowel prep and usually sedation. Repeated every 10 years if normal.
• CT colonography (virtual colonoscopy). Uses a CT scanner, no sedation, but still needs prep. If polyps are found, a regular colonoscopy is usually needed. Every 5 years.
• Flexible sigmoidoscopy. Examines the lower colon only, lighter prep, usually no sedation. Every 5 to 10 years, sometimes with a stool test.

Two blood-based tests are FDA-approved, but they are not yet part of first-line screening guidelines.

Each test trades convenience against thoroughness — your care team can help you weigh them.

The decision often comes down to what fits your life and preferences. Things to think about include:

• Your age, health, and family history
• How invasive the test is
• Whether it needs prep or sedation
• How often it must be repeated
• Cost and insurance coverage

There is a saying worth remembering: the best screening test is often the one you will actually complete — and keep completing on schedule. A simpler test done on schedule every time does more good than a thorough one you keep putting off, as long as a positive result is followed by a prompt colonoscopy. That last part is the condition: a positive stool test only helps if the colonoscopy follows.

Reliability matters as much as the test itself — pick one you'll actually stick with.

No screening test is a diagnosis by itself. A positive stool test, or an abnormal finding on any test, means something needs a closer look — usually a colonoscopy to examine the colon directly and remove or biopsy anything suspicious.

Many positive results turn out to be polyps or harmless causes. What matters most is following through with the recommended next step. Skipping the follow-up undoes the benefit of screening in the first place.

Colorectal cancer screening is covered without a deductible or copay by most health insurance policies, according to the CDC. Medicare also covers it. What happens next can be billed differently. That covers a follow-up colonoscopy after a positive stool test, or a polyp removed during a screening colonoscopy. The rules have changed in recent years and vary by plan, so check rather than assume. Medicare's page on this covers Medicare. Otherwise read your own plan documents. Ask before the procedure how it will be billed if a polyp is found.

Screening is widely covered — but confirm how follow-up procedures are billed if something is found.

• National Cancer Institute: Colorectal Cancer Screening fact sheet
• CDC: Colorectal cancer screening