Screening for Colorectal Cancer: A Guidance Statement From the American College of Physicians FREE

The American College of Physicians (ACP) developed these recommendations. Members of the ACP are internists—specialists in the care of adults.

Colorectal cancer (cancer of the large intestine [colon] or rectum) starts as a noncancerous growth (polyp) that grows slowly and becomes cancerous. By the time colorectal cancer causes symptoms, it is often incurable. Screening of persons without symptoms can detect polyps and early-stage cancer. Screening tests for colorectal cancer include stool testing, sigmoidoscopy, optical colonoscopy, and virtual colonoscopy. Sigmoidoscopy uses a flexible instrument with a camera on its tip to examine the rectum and lower colon. Optical colonoscopy uses a similar instrument to look at the entire colon and allows doctors to take samples and remove polyps. Virtual colonoscopy uses computed tomography to look for abnormalities. Laxatives are needed before both types of colonoscopy. Optical colonoscopy should be used as a follow-up for abnormalities found by other tests.

Organizations have guidelines for colorectal cancer screening but provide different advice. The ACP evaluated available guidelines to help doctors and patients make better decisions.

The National Guideline Clearinghouse (NGC) is a Web site developed by the U.S. government to make clinical guidelines widely available. The authors searched the NGC for U.S. guidelines about colorectal cancer screening and found 4 guidelines. They evaluated each guideline using a published instrument that considers 23 standard criteria for the quality of guidelines. They also reviewed a commonly used 2009 guideline from the American College of Gastroenterology that is not included in the NGC.

The U.S. Preventive Services Task Force guideline received the highest quality rating, and the American College of Radiology guideline received the lowest quality rating. The Institute for Clinical Systems Improvement guideline and the joint guideline from the American Cancer Society, the U.S. Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology were in the middle. Reviewed guidelines recommended starting screening between age 40 and 50 years but varied in their recommendations for screening frequency and choosing one test over another. Risks for colorectal cancer include increasing age, African American race, and family history. The authors noted an absence of evidence to support recommendations for how often to screen or that one screening test was better than others.

When considering screening for colorectal cancer, doctors should evaluate patient risk. For patients at average risk for colorectal cancer, doctors should recommend screening starting at age 50 years. Patients with a parent, sibling, or child with colorectal cancer should begin screening at 40 years or 10 years younger than the age at diagnosis of the patient's youngest affected relative (whichever is younger). Tests appropriate for screening average-risk patients include stool-based tests, flexible sigmoidoscopy, or optical colonoscopy. Patient preference and availability and adverse effects of the tests should guide choice. High-risk patients should get optical colonoscopy. Doctors should not recommend colorectal cancer screening for patients older than 75 years or patients who are likely to die within 10 years.

The NGC does not include all guidelines.