Expert Q&A: Discussing Recent ACP Guidance on CRC Screening, Reconciling Differences Across Other Screening Guidelines

Gastroenterology Advisor spoke to Dr. Robert McLean, President of the American College of Physicians (ACP), and Dr. Timothy Wilt, Chair of ACP's Clinical Guidelines Committee to address several of these questions from the Colorectal Cancer Screening Guidance Statement.

The American College of Physicians (ACP) has released a new guidance statement on the screening of colorectal cancer (CRC) in asymptomatic, average-risk adults. Statements in the guidance document, published in the Annals of Internal Medicine, provide recommendations on when screening should take place and suggested screening tests and the associated intervals at which these tests should be performed, as well as age-based recommendations regarding screening discontinuation.1

Several guidelines have been published on screening for CRC; yet many of these guideline documents disagree with regard to their recommendations. The ACP Clinical Guidelines Committee (CGC) searched the National Guideline Clearinghouse and the Guidelines International Network library for CRC screening guidelines in an effort to develop a consensus guidance statement on CRC screening in average-risk adults. Guidelines from the American College of Radiology (ACR), Canadian Task Force on Preventive Health Care (CTFPHC), United States Preventive Services Task Force (USPSTF), American Cancer Society (ACS), Scottish Intercollegiate Guidelines Network (SIGN), and the United States Multi-Society Task Force (MSTF) on Colorectal Cancer were used to develop this consensus.

Age-Based Recommendations and Patient Preferences for Guiding CRC Screening

Based on the available evidence, regular CRC screening reduces disease-specific mortality in average-risk adults; the reduction associated with CRC screening increases with age, particularly in individuals aged ≥50 years. In turn, the ACP CGC suggests initiating CRC screening in average-risk adults between the ages of 50 and 75 years, as suggested in the CTFPHC and USPSTF guidelines.

The writing committee suggests patients’ values and preferences may also play a role in determining whether or not to initiate screening, regardless of age. Patients should also be involved in the decision-making process regarding which CRC screening tests to choose. Decision making should involve a discussion between clinician and patient on the benefits, harms, costs, and frequency of each test. Considering that each test carries with it a risk for potential harm, clear communication on screening risks is important to ensure quality care.

A test the ACP recommends is fecal immunochemical testing or high-sensitivity guaiac-based fecal occult blood testing, which should be conducted every 2 years. Colonoscopy is another suggested test, and should be performed every 10 years. Flexible sigmoidoscopy, conducted every 10 years, plus fecal immunochemical testing, performed every 2 years, are also recommended.

Discontinuation of CRC Screening in Average-Risk Adults Age >75 Years

The risk for harm from CRC screening increases with age and the harms associated with screening may outweigh the potential benefits in older patients. While there may be a benefit to CRC screening in individuals age >75 years who have no history of screening, there is no evidence of benefit in patients in this age group who have had CRC screening with negative results. Considering the average life expectancy of adults in the United States and the increasing harm of CRC with increasing age, the ACP suggests discontinuing CRC screening in adults age >75 years or people with an estimated life expectancy of ≤10 years.

Can the ACP Statement Reconcile CRC Screening Disagreements in Current Guidelines?

Screening for CRC is recommended in most CRC prevention and management guidelines, which likely has resulted in the reduction of CRC-specific mortality observed in recent years. Despite this recommendation, evidence-based guidelines often make different recommendations, causing a lack of uniformity in suggestions for clinical practice.

In an accompanying editorial, Michael Pignone, MD, MPH, from the University of Texas, wrote that several important questions about CRC screening have not been and may never be directly addressed in clinical trials.2 These questions, which were addressed in the new ACP statement, involve deciding which testing strategies clinicians should consider in shared decision making and when to discontinue CRC screening in adult patients.

Many of the current CRC screening guidelines vary in their approach to providing recommendations and many do not consider cost-effectiveness modeling in guideline development. Age-based recommendations for screening also vary across organizational guidelines for CRC screening. Few guideline documents, if any, have sought to determine “whether screening adults in their 50s is worth the resources required, compared with waiting until age 60 years,” noted Dr. Pignone.

Gastroenterology Advisor spoke to Dr. Robert McLean, President of the American College of Physicians (ACP), and Dr. Timothy Wilt, Chair of ACP’s Clinical Guidelines Committee to address several of these questions from the Colorectal Cancer Screening Guidance Statement.

Editor’s note: These interviews were lightly edited for length and clarity.

Gastroenterology Advisor: Different organizations have varying criteria for evaluating or assessing the quality and certainty of evidence. This can result in different final clinical recommendations. How should a healthcare provider approach the various guidelines? Which testing strategies should be considered in shared decision making?

ACP Response: As noted below, ACP’s Clinical Guidelines Committee develops rigorous guidance statements when there are different clinical recommendations. The purpose of ACP guidance statements is to carefully evaluate existing guidelines and the accompanying evidence to assist clinicians in reconciling different recommendations and provide optimal care for their patients. We recommend that clinicians use ACP guidance statements for high-quality practice implementation. ACP’s CRC screening guidance statement encourages physicians and patients to select the screening test based on a discussion of the benefits, harms, costs, availability, frequency, and patient preferences. Suggested screening strategies should focus on average risk adults between the ages of 50 and 75 who have an average life expectancy of at least 10 years and include high sensitivity fecal occult blood testing every 2 years, colonoscopy every 10 years, or flexible sigmoidoscopy every 10 years plus high sensitivity fecal occult blood testing every 2 years. We also suggest that clinicians discontinue screening for CRC in average-risk adults older than 75 years or adults with a life expectancy of ≤10 years because screening is unlikely to be beneficial and can cause harms.

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Gastroenterology Advisor: Although Qaseem and colleagues used state-of-the-art methods for evaluating guidelines, including engagement of patient representatives, they did not perform any independent systematic reviews of the primary evidence. What is the rationale for not incorporating the latest evidence?

ACP Response: ACP included the most up-to-date guidelines and the latest associated evidence. ACP develops guidance statements on topics when several guidelines are available but have conflicting recommendations. The goal of ACP guidance statements is to provide clinicians with a rigorous review of the available guidelines and their cited evidence and to develop subsequent guidance based on an assessment of the benefits and harms reported by the guidelines.

Gastroenterology Advisor: One controversial aspect of the ACP guidance for providers in the United States is the recommendation of biennial rather than annual stool testing, which may have been based on a lack of clear additional benefit from annual testing in randomized trials. However, these studies were not powered to rule out moderate differences in effectiveness. What, in your opinion, constitutes sufficient magnitude and certainty of effect to justify a recommendation for biennial testing?

ACP Response: ACP believes the evidence supports biennial rather than annual stool testing, alone or with flexible sigmoidoscopy. Most randomized trials examined biennial not annual stool testing. A single large US randomized trial that evaluated both annual and biennial testing found no significant differences in CRC or all-cause mortality through 30 years between annual and biennial testing. Therefore, screening biennially rather than annually would result in similar reductions in CRC and overall mortality while decreasing harms and the burden of screening, including false positive test results and subsequent and diagnostic colonoscopies.

Gastroenterology Advisor: Like all tests and procedures, CRC screening tests have both potential benefits and potential harms. Another key area of possible controversy addressed in the ACP guidance is the starting age for screening. What were the factors that went into this recommendation? Also, as cost-effective analysis supports starting screening at age 45 years compared with 50 years will produce additional benefit at additional cost but the additional cost per quality-adjusted life-year gained is reasonable. Should average-risk adults begin screening before age 50 years?

ACP Response: ACP’s guidance statement suggests that average-risk adults should undergo screening beginning at age 50 years and continuing through age 75 years. Beginning earlier has not been convincingly demonstrated to have benefits that exceed harms and the recommendations from some organizations rely on modeling studies that often use information with optimistic assumptions and uncertain quality. The 2 highest quality guidelines (USPSTF and CTFPS) both recommend screening beginning at age 50. ACP also suggests that starting later than age 50 years or screening less frequently is reasonable for some individuals who prefer to be screened less frequently because evidence indicates that the trade-offs between earlier and more frequent screening often depends on patient preferences. ACP agrees with the editorial that a higher-value strategy is to ensure that screening is available and increase implementation in healthy average-risk adults between ages 50 and 75 who are interested in screening.

Gastroenterology Advisor: What is the optimal interval after a negative result on a screening test in patients with an average risk for CRC?

ACP Response: ACP guidance statements provide suggestions for screening intervals by test that pertain to individuals at average risk and who have negative screening results every 2 years for stool based tests, every 10 years for colonoscopy, and every 10 years for flexible sigmoidoscopy plus every 2 years stool-based tests. As noted, less frequent screening such as a colonoscopy every 15 rather than every 10 years may be reasonable for many individuals. Additional research is needed to best understand the implications for well-informed individuals who would like less intensive screening.


  1. Qaseem A, Crandall CJ, Mustafa RA, Hicks LA, Wilt TJ. Screening for Colorectal Cancer in Asymptomatic Average-Risk Adults: A Guidance Statement From the American College of Physicians. Ann Intern Med. 2019; 171:643-654.
  2. Pignone M. Reconciling Disparate Guidelines: The American College of Physicians Colorectal Cancer Screening Guidance Statement. Ann Intern Med. 2019; 171:671-672.