Screening for Colorectal Cancer

The US Preventive Services Task Force (USPSTF) has published updated recommendations on screening for 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 and is the second leading cause of cancer death in the United States. 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.

There are several tests that can be used to detect colorectal cancer. These include

• Colonoscopy uses a scope to look at the inside of the entire colon and rectum. It requires a bowel preparation that involves using laxatives to empty the colon beforehand.

• Flexible sigmoidoscopy uses a scope to look at the rectum and part of the colon.

• CT colonography (“virtual colonoscopy”) is a special type of computed tomography (CT) scan that looks at the inside of the colon and rectum. It is noninvasive and does not involve a scope, but there is still some bowel preparation required.

• Stool-based tests involve collecting a sample of stool and looking for either blood or abnormal genetic material in the stool, which can be signs of cancer. Examples include the fecal occult blood test, fecal immunochemical test, and stool DNA test.

There are pros and cons to each of these tests, and each has its own optimal screening interval. These different tests are discussed in greater detail in a separate Patient Page. The USPSTF does not specifically recommend using one test over another.

This USPSTF recommendation applies to adults aged 50 to 85 years 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 family history, inflammatory bowel disease, or a known history of colon polyps. There are different recommendations for adults aged 50 to 75 years vs adults aged 76 to 85 years. The USPSTF does not recommend routine screening for colorectal cancer in adults aged 86 years or older.

Benefits of screening are that cancers can be found at earlier stages, and polyps can be found and removed before they become cancerous. For adults aged 50 to 75 years, there is good evidence that screening decreases the overall chance of dying of colorectal cancer. For adults aged 76 to 85 years, the mortality benefit of screening is smaller. Among this older group, there is more benefit in screening those who have never before been screened compared with those who have already undergone screening.

Harms of screening arise mostly from potential effects of colonoscopy, which is the most invasive of the testing procedures. These can include side effects of the bowel preparation or effects of the sedation used during the procedure.

Given the current evidence, the USPSTF has concluded with high certainty that the benefits of screening for colorectal cancer in adults aged 50 to 75 years substantially outweigh the potential harms. For adults aged 76 to 85 years, the USPSTF has concluded with moderate certainty that the benefit of screening those who have already been screened before is small.

The USPSTF recommends screening for colorectal cancer in adults aged 50 to 75 years (called an “A” recommendation). The USPSTF recommends an individualized decision regarding screening in adults aged 76 to 85 years based on overall health and screening history (“C” recommendation).

Published Online: June 15, 2016. doi:10.1001/jama.2016.7569.

Source: US Preventive Services Task Force. Screening for colorectal cancer: US Preventive Services Task Force recommendation statement. JAMA. doi:10.1001/jama.2016.5989

Topic: Preventive Medicine