Colon Cancer Screening: Care Instructions

Overview

Colorectal cancer occurs in the colon or rectum. That's the lower part of your digestive system. It often starts in small growths called polyps in the colon or rectum. Polyps are usually found with screening tests. Depending on the type of test, any polyps found may be removed during the tests.

Colorectal cancer usually does not cause symptoms at first. But regular tests can help find it early, before it spreads and becomes harder to treat.

Your risk for colorectal cancer gets higher as you get older. Experts recommend starting screening at age 45 for people who are at average risk. Talk with your doctor about your risk and when to start and stop screening. You may have one of several tests.

What are the main screening tests for colon cancer?

The screening tests are:

Stool tests.

These include the guaiac fecal occult blood test (gFOBT), the fecal immunochemical test (FIT), and the combined fecal immunochemical test and stool DNA test (FIT-DNA). These tests check stool samples for signs of cancer. If your test is positive, you will need to have a colonoscopy.

Sigmoidoscopy.

This test lets your doctor look at the lining of your rectum and the lowest part of your colon. Your doctor uses a lighted tube called a sigmoidoscope. This test can't find cancers or polyps in the upper part of your colon. In some cases, polyps that are found can be removed. But if your doctor finds polyps, you will need to have a colonoscopy to check the upper part of your colon.

Colonoscopy.

This test lets your doctor look at the lining of your rectum and your entire colon. The doctor uses a thin, flexible tool called a colonoscope. It can also be used to remove polyps or get a tissue sample (biopsy).

A less common test is CT colonography (CTC). It's also called virtual colonoscopy.

Who should be screened for colorectal cancer?

Your risk for colorectal cancer gets higher as you get older. Experts recommend starting screening at age 45 for people who are at average risk. Talk with your doctor about your risk and when to start and stop screening.

How often you need screening depends on the type of test you get:

Stool tests.

Every year for FIT or gFOBT.

Every 1 to 3 years for sDNA, also called FIT-DNA.

Tests that look inside the colon.

Every 5 years for sigmoidoscopy. (If you do the FIT test every year, you can get this test every 10 years.)

Every 5 years for CT colonography (virtual colonoscopy).

Every 10 years for colonoscopy.

Experts agree that people at higher risk may need to be tested sooner and more often. This includes people who have a strong family history of colon cancer. Talk to your doctor about which test is best for you and when to be tested.