Colorectal cancer (CRC) ranks third for both men and women as the most common cause of cancer death in the United States (U.S.). The American Cancer Society predicts 149,500 cases and 52,980 deaths from CRC in 2021 (Siegel et al., 2021). Over half of these cases and deaths can be attributed to modifiable risk factors including physical inactivity, an unhealthy diet, excess body weight, smoking, and high alcohol intake (Siegel et al., 2020). Most CRCs start as polyps that turn to cancer over time. This development process allows for cancer prevention by screening for and removing these polyps before they turn to cancer or by identifying early-stage CRCs, which are most treatable (Shaukat et al., 2021). Most CRC cases occur in people 50 years and older; however, about 12% occur in people younger than 50 years (Siegel et al., 2020). Fortunately, CRC incidence and mortality have steadily declined due to screening uptake, smoking reduction, and surgical and treatment improvements (Shaukat et al., 2021).
Although older people have had a decline in CRC incidence, younger people have had an increase in incidence, particularly for rectal cancers. Hence, the CRC patient population is shifting to younger people (Siegel et al., 2020). People born around 1990 have twice the colon cancer risk and four times the rectal cancer risk compared with those born around 1950 (Siegel et al., 2017). The reasons for this increased incidence of early-onset CRC are not known but are likely due to diet and lifestyle (Siegel et al., 2020).
Colorectal Cancer Screening Guidelines
Multiple organizations have developed CRC screening guidelines for average risk individuals. The American College of Gastroenterology (ACG) recently released an update of their 2009 recommendations (Rex et al., 2009). This update comes after the recent updates by the American Cancer Society (Wolf et al., 2018) and the U.S. Preventive Services Task Force (USPSTF, 2021). The focus of this report is to summarize the 2021 ACG CRC screening guidelines for average risk individuals (Shaukat et al., 2021).
Colorectal Cancer Screening: Average Risk
The USPSTF defines "average risk" as adults without symptoms and no previous adenomatous polyps, CRC, or inflammatory bowel disease or a family or personal history of genetic syndrome that increases propensity to CRC such as familial adenomatous polyposis or Lynch syndrome (USPSTF, 2021). The ACG's latest guideline makes a conditional recommendation to screen people of average risk between ages 45 and 49 years (Shaukat et al., 2021). This recommendation is consistent with the American Cancer Society's 2018 qualified recommendation (Wolf et al., 2018) and the USPSTF's (2021) Grade B recommendation. Grade B indicates a recommended service with a high certainty of a moderate net benefit or moderate certainty that the net benefit is moderate to substantial; providers should either provide or offer this service. For more information on the USPSTF grades, visit https://www.uspreventiveservicestaskforce.org/uspstf/us-preventive-services-task.
The ACG makes a strong recommendation to screen those of average risk between the ages of 50 and 75 years. The decision to screen past age 75 is individualized based upon health status, likelihood to survive 10 more years, risks and benefits of screening, personal screening history, and personal values. The benefits of polypectomy for CRC prevention lags by 7-10 years, so the elderly who may not live another 7-10 years might have no benefit to CRC screening. Further, the risk of dying of other causes increases with age whereas the risks of a colonoscopy preparation (electrolyte imbalance, dehydration) and procedure (perforation, bleeding) also increase with age (Shaukat et al., 2021).
Colorectal Cancer Risk Factor: Family History
The birth-to-death risk of getting CRC is 1 of 23 males and 1 of 25 females (Siegel et al., 2021). People with a family history of CRC have approximately double the risk of getting CRC; however, multiple factors affect this multiplier. Examples include the age of the person under consideration, the ages of the relatives at the time of CRC diagnosis, their degree of relationship, and the numbers of relatives affected. Providers should obtain and examine a three-generation family history. A clustering of cancer cases and a younger age at diagnosis might indicate an inherited CRC syndrome necessitating earlier screening. Similarly, advanced polyps in these family members are a reason for earlier screening. The ACG recommends the use of colonoscopy for these higher risk patients and that screening start at 40 years or 10 years before the age at which the youngest relative was affected, whichever age is younger. In addition to this earlier screening start, they recommend a 5-year instead of 10-year interval on the screening colonoscopies. The ACG has a conditional recommendation to consider genetic evaluation when multiple family members are affected, especially at a younger age (Shaukat et al., 2021).
African Americans
African Americans have a higher rate of CRC and a higher stage-adjusted CRC mortality due to a lower screening rate and other factors. Health systems that focus on equal access, however, do not have this disparity. Outreach programs and additional effort are necessary to reduce this disparity for African Americans, increase their screening rates, and reduce their CRC incidence and mortality (Shaukat et al., 2021).
Colorectal Cancer Screening Options
The ACG considers two types of screening options: (1) one-step colonoscopy, which is both diagnostic and therapeutic, and (2) two-step options, all of which require a follow-up colonoscopy when the first step is positive. The ACG prefers the colonoscopy, as this test allows the detection of early-stage CRC and also allows the removal of polyps. Their second most preferred test is the fecal immunochemical test (FIT), annually. This test replaced the guaiac fecal occult blood testing because of its higher sensitivity, requirement for a single sample, better patient adherence, and no medication or dietary restrictions. The FIT, when completed annually, has a comparable life years gained when compared with a colonoscopy at the recommended interval of every 10 years (Shaukat et al., 2021).
The use of these two-step options necessitates a quality assurance program that ensures this follow-up colonoscopy gets completed for all positive tests. Patients who are unable or unwilling to do either colonoscopy or FIT have options including flexible sigmoidoscopy, multitarget stool DNA test (mtsDNA), computerized tomography colonography (CTC), or colon capsule (CC; Table 1). The best test is the test that patient will have done (Shaukat et al., 2021).
The mtsDNA is an assay for mutant KRAS, methylated BMP3, methylated NDRG4, plus a FIT. The mtsDNA has a higher sensitivity for advanced adenoma (42% vs. 24% with FIT alone) and CRC (92% vs. 74% with FIT alone) but lower specificity. The interval for testing is every 3 years (Shaukat et al., 2021).
The flexible sigmoidoscopy examines, visually, up to the sigmoid, and if positive for adenomas or other findings, the patients are referred for colonoscopy. This test is less used in the U.S., as it is uncomfortable and no sedation is provided. The interval for this testing is every 5-10 years (Shaukat et al., 2021).
The CTC is highly sensitive and specific (up to 98%). There are, however, concerns regarding detection of right-sided and flat polyps and operator dependence. Any findings on the CTC necessitate a follow-up colonoscopy. The interval for this testing is every 5 years (Shaukat et al., 2021).
The CC is used after an incomplete colonoscopy or for patients with lower gastrointestinal bleeding but at too high risk to have a colonoscopy. The CC with positive findings should be followed by diagnostic colonoscopy. The interval for this testing is every 5 years (Shaukat et al., 2021).
Colorectal Cancer Chemoprotection
The USPSTF first made a recommendation on the use of a low-dose aspirin for the prevention of CRC in their 2016 guideline (USPSTF, 2016). The ACG has added the recommendation of daily aspirin for people aged 50-69 years, with a cardiovascular disease risk of greater than or equal to 10% over the next 10 years, provided they are not at increased risk for bleeding and could take aspirin for at least 10 years. However, the recommendations for CRC screening remain the same when people do take aspirin (Shaukat et al., 2021).
Quality Colonoscopy Services
Any positive two-step CRC screening option needs to be followed by a colonoscopy. The ACG strongly recommends endoscopists measure cecal intubation rates and have a success threshold of 95% for screening colonoscopies. They also have evidence to support measuring adenoma detection rates (ADRs), with the goal of 20% for females, 30% in males, and 25% overall for all screening colonoscopies. These goals are to reduce the incidence of postcolonoscopy CRC (PCCRC), which is cancer that occurs after a colonoscopy, sometimes due to missed lesions. Their recommended withdrawal time (WT) is 6 minutes to allow for adequate visualization of the colon mucosa (Shaukat et al., 2021).
Health System Support of Screening
Adherence to CRC screening recommendations remains problematic, particularly for some populations. Numerous strategies have been studied to promote screening adherence and should be adopted by health systems. Some health systems have recorded screening rates over 80%. Patient navigators assist patients to overcome barriers to screening and promote adherence. Postage-paid, mailed stool tests assist patients to complete in-home testing. Patient reminders via mail, texts, phone calls, and patient portals improve adherence as do peer coaches (volunteer patients). There are clinician-targeted interventions such as provider education, electronic health record prompts, and quality improvement efforts to encourage providers to offer CRC screening. Provider recommendation is one of the top reasons patients do get screened. Clinical support tools can assist providers with patient education and shared decision-making, which promotes the patients' choices to become screened. Failure to complete an ordered colonoscopy may be resolved through mailed and phoned reminders, face-to-face counseling, seminars, helplines, and patient navigators (Shaukat et al., 2021).
Implications for the Gastroenterology Nurse
Gastroenterology nurses work with endoscopists who are members of the ACG. Nurses at all levels assist with adherence to these guidelines. The nursing role includes an emphasis on patient education, which helps them adhere to these best recommendations. Nurses record the cecum time, ensure a cecal photograph is made, monitor the WT, and collect the data for the ADRs. Nurses follow up with patients who do not present for their colonoscopy and assist with overcoming any barriers determined. As members of the interdisciplinary team, nurses review and revise structures and processes in electronic documentation such as providing adequate prompts to order CRC screening, statistical analyses of performance, and coordinating follow-up with patients. Nurses participate in quality improvement programs that assist the gastroenterology team to effectively adhere to these important guidelines.
Conclusion
The trend toward early-onset CRC has prompted organizations including the ACG to adopt a screening age of 45 years. There are a variety of CRC screening methods, each with advantages and disadvantages, but any screening method reduces both the morbidity and mortality of CRC. The ACG recommends either the colonoscopy (every 10 years) or the FIT (annually) for average risk patients as primary screening methods. Unfortunately, America's screening rates could improve. There are health system strategies that have promoted over 80% of the population to be screened. Special emphasis on CRC screening for African Americans will help reduce their health disparity. Referrals to endoscopists who meet the ACG quality standards will help ensure patients will not have missed lesions, which may result in postcolonoscopy cancers.
REFERENCES