Perspectives

Colorectal cancer screening guidelines: How to make best use of all of them


 

The recent death of “Black Panther” star Chadwick Boseman has resulted in colorectal cancer (CRC) screening guidelines receiving more attention. Mr. Boseman was diagnosed with Stage 3 CRC in 2016 and underwent treatment. He passed away 4 years later at the young age of 44.

Dr. Santina J. Wheat, program director of Northwestern’s McGaw Family Medicine residency program at Humboldt Park, Chicago

Dr. Santina J.G. Wheat

Mr. Boseman’s death has highlighted two important concerns about current screening guidelines for CRC. These include racial disparities in patients with colon cancer and the fact that more younger patients are getting this disease.

There are at least three different sets of CRC screening recommendations from different trusted professional organizations that primary care physicians must decide how to follow. These organizations each published their guidelines indicating review of the best available evidence. On first glance there is discrepancy between these guidelines, but a closer look at them reveals they have a lot of similarities.

The U.S. Multi-Society Task Force of Colorectal Cancer (MSTF), which represents the American College of Gastroenterology, the American Gatroenterological Association, and the American Society for Gastrointestinal Endoscopy, is one of the organizations that offers guidelines. The MSTF recommends CRC screening for non-African American average risked persons at the age of 50 years (strong recommendation; moderate quality evidence). The first-tier options for this recommendation are to have a colonoscopy every 10 years or annual fecal immunochemial test. Additionally, the MSTF recommends beginning screening of African Americans at age 45 years (weak recommendation; very-low-quality evidence). This recommendation cites higher incidence rates, earlier mean age at onset, higher proportion of cancers before age 50 years and late-stage presentation. The MSTF indicates that the increased rate of CRC at an earlier age in African Americans is caused by a combination of biologic and societal factors, but do not point to what those are. This earlier screening is not backed by evidence that it in fact improves morbidity or mortality outcomes. The MSTF also address screening among high-risk individuals. Those with first degree relatives with CRC or advanced adenomas diagnosed before the age of 60 years should be screened beginning at age 40 years or 10 years younger than the age the relative was diagnosed, whichever comes first, according to the MSTF recommendations. These individuals should have a colonoscopy every 5 years, the MSTF says. Those with first degree relatives with CRC or advanced adenomas diagnosed at older than 60 years should have CRC beginning at 40 years, though with the same testing intervals as average-risk individuals.1

The American College of Physicians (ACP) and the American Academy of Family Physicians (AAFP), however, endorse the guidelines set forth by the United States Preventive Services Task Force (USPSTF). These guidelines were published in 2016 in the JAMA and notably are currently under review. These guidelines recommend routine screening for those at average risk at the age of 50 years. In the publication of these guidelines, the increasing incidence of CRC in those under 50 was acknowledged. It is however stated that the modest benefit of earlier diagnosis made via screening is not better than the increased risk of increased lifetime colonoscopy.2

The publication specifically addresses the disparity among Black adults who have the highest incidence and mortality rates in comparison with other racial/ethnic groups. These guidelines specifically state that there are higher rates of colon cancer among black adults. They however clarify that they think it is because of decreased screening and treatment in this group. When compared with other groups and the screening and treatment is controlled for, there is no longer a difference. Lowering the age for starting screening, therefore, won’t help resolve the disparity because the higher cases in Black adults has resulted from not enough Black adults being screened at the recommended age of 50, according to the USPSTF recommendation statement. As such, rather than changing the age of screening for Black adults, this publication recommends efforts to ensure that screening, follow-up, and treatment are received.

The USPSTF specifically did not include adults with known disorders that have a genetic predisposition to CRC or those with a first degree relative with CRC. They instead refer to other professional organizations for these recommendations.2

The American Cancer Society (ACS) also had a separate guideline published in CA: A Cancer Journal for Clinicians. It provides a qualified recommendation that CRC screening begin at age 45 years for those with average risk. The guideline also includes a strong recommendation for CRC screening beginning at age 50 years. The qualified recommendation for the younger age group is based on the incidence of colorectal cancer being similar between those aged 45-49 and those aged 50-54 years. The ACS also hypothesized that screening at an earlier age will decrease the disparity among population groups with a higher burden. Importantly, this updated guideline prioritized incidence reduction rather than mortality reduction. The ACS also stressed the need for a multipronged approach to mitigate barriers to CRC screening at the individual, provider, organizational, and policy levels. Similar to the USPSTF, the ACS did not address the screening of those with known disorders that have a genetic predisposition to CRC or those with a first degree relative with CRC.3

In all of the publications discussing CRC screening guidelines, it is stressed that there is not sufficient uptake of any of these recommendations. Rather than conduct earlier screening, in my opinion, we should focus on programmatic ways to ensure that the existing screening recommendations are followed. This is a space in which we can help affect the disparity seen among population groups.

The most important screening test is the one that patients are willing to use. Primary care physicians can use any of these guidelines to have conversations with patients about risk and when to start screening. Although these guidelines may seem to be different from each other, each one includes strong recommendations with the same information.

Additional studies should be done to determine the benefits and harms of screening in patients with known risk factors such as obesity, cigarette smoking, diabetes, high consumption of alcohol, high consumption of red meat and processed food, inactivity, and low intake of dietary fiber, fruits, and vegetables. It is possible that the higher burden of disease among Black adults is related to societal factors leading to increased obesity and dietary habits that increase rates of CRC.

Primary care physicians would be better served by a tool that allows for risk stratification to help guide early screening for all patients. For certain patients, such a tool might result in them qualifying for screening that begins at a later age than the current guidelines recommend. Finally, primary care physicians must remember that these are just the guidelines for screening for CRC. They all specifically exclude patients experiencing any symptoms. As such, patients with unexplained bleeding, anemia, weight loss, and other symptoms should be evaluated fully, including being considered for colonoscopy to diagnose CRC. Primary care physicians should use these guidelines to screen their asymptomatic patients and should ensure that they provide evaluation of any of the symptoms of CRC.

Dr. Wheat is a family physician at Erie Family Health Center in Chicago. She is also program director of Northwestern’s McGaw Family Medicine residency program at Humboldt Park, Chicago. Dr. Wheat serves on editorial advisory board of Family Practice News.

References

1. Rex DK et al. Gastrointest Endosc. 2017;86(1):18-33.

2. US Preventive Services Task Force. JAMA. 2016;315(23):2564-2575.

3. Wolf AMD et al. CA Cancer J Clin. 2018 Jul;68(4):250-281.

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