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JAMA Patient Page
May 18, 2021

Screening for Colorectal Cancer

Author Affiliations
  • 1Associate Editor, JAMA
JAMA. 2021;325(19):2026. doi:10.1001/jama.2021.6557

The US Preventive Services Task Force (USPSTF) has recently published updated recommendations on screening for colorectal cancer.

What Is Colorectal Cancer?

Colorectal cancer refers to cancer of either the colon (large intestine) or the rectum, which are the lower parts of the gastrointestinal tract. Colorectal cancer mostly affects older adults. However, in recent years, the rate of diagnosis in adults younger than 50 years has been increasing. Symptoms of colorectal cancer include changes in bowel habits, abdominal pain, and sometimes blood in the stool. Colorectal cancer can be treated by surgery, chemotherapy, or sometimes radiation therapy.

What Tests Are Used to Screen for Colorectal Cancer?

Direct visualization looks at the colon and rectum using a scope and camera (colonoscopy or flexible sigmoidoscopy) or by computed tomography (CT) scan (CT colonography, also called virtual colonoscopy). These tests require bowel preparation using laxatives to empty the colon and rectum beforehand. Stool-based tests involve collecting a sample of stool to look for either blood or abnormal genetic material, both of which can be signs of cancer. Examples include the high-sensitivity fecal occult blood test, fecal immunochemical test, and stool DNA test.

There are pros and cons to each of these tests, and there are different screening intervals recommended for each. The USPSTF does not specifically recommend using one test versus another.

What Is the Patient Population Under Consideration for Screening for Colorectal Cancer?

This USPSTF recommendation applies to adults aged 45 years or older who do not have symptoms of colorectal cancer. It does not apply to people who are at higher risk of colorectal cancer, such as those who have a strong colorectal cancer family history, inflammatory bowel disease, or a history of colon polyps.

What Are the Potential Benefits and Harms of Screening for Colorectal Cancer?

Screening can prevent people from dying of colorectal cancer. Clinical trials show that screening adults aged 50 to 75 years decreases colorectal cancer deaths. Computer simulation studies suggest that starting screening at age 45 years may help some people live longer than if they started screening at age 50 years. For people aged 76 to 85 years, the benefit of screening is smaller. Among this older group, those who have never been screened are more likely to benefit. Harms of screening are primarily due to colonoscopy (either initial screening colonoscopy or colonoscopy done to follow up abnormal results of other screening tests). Uncommon but potential serious harms include bleeding or infection from the procedure.

How Strong Is the Recommendation to Screen for Colorectal Cancer?

Given the current evidence, the USPSTF concludes with high certainty that the net benefit of screening for colorectal cancer in adults aged 50 to 75 years is substantial. The USPSTF concludes with moderate certainty that the net benefit of screening for colorectal cancer in adults aged 45 to 49 years is moderate and that the net benefit of screening for colorectal cancer in adults aged 76 to 85 years who have been screened in the past is small. Adults who have never been screened for colorectal cancer are more likely to benefit.

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Conflict of Interest Disclosures: None reported.

Source: US Preventive Services Task Force. Screening for colorectal cancer: US Preventive Services Task Force recommendation statement. JAMA. Published May 18, 2021. doi:10.1001/jama.2021.6238