Colon Cancer Screening: American Cancer Society Guidelines Update

Recently, the American Cancer Society (ACS) revised their colorectal cancer (CRC) screening guidelines and recommended that people at average risk for CRC undergo screening starting at age 45.¹ This represents a change from the prior ACS guidelines, which recommended screening at age 50 for people at average risk for CRC. This change was a result of the increasing CRC incidence in younger people, modeling analyses supporting a benefit to starting screening earlier with an expected drop in CRC incidence and mortality.

To develop this new guideline, the ACS used published systematic reviews and clinical studies, modeling studies, and a panel of experts to perform a detailed review of all of the potential benefits and risks of any recommendations they planned to propose. The recommendation to lower the testing age to 45 years was based on the increasing CRC incidence in adults younger than 50 years.^2,3,4Despite there being a steady decline in the incidence of CRC in people 50 years and older, there has been a dramatic 51% increase in CRC incidence in patients younger than 50 years since 1994.⁴Interestingly, there has also been evidence to support an increase in the prevalence of polyps 9 mm or larger in people younger than 50 years.⁵Therefore, earlier removal of these larger, more “high-risk” polyps could help reduce the risk of CRC in the future. 

As starting CRC screening for all patients at age 45 years would represent a relatively new trend, there is a dearth of data available to review the potential benefits of this strategy. Therefore, several modeling analyses were performed during the development of the ACS guidelines that predicted a significant benefit and an expected reduction in CRC incidence and mortality. The model calculated that a colonoscopy every 10 years for patients aged 45 to 75 years had 6.2% life-years gained (LYG) and 17% more colonoscopies per 1000 adults over a lifetime of screening compared with the traditional model, which specifies testing every 10 years from ages 50 to 75 years.¹

It is too soon to predict how the ACS recommendations will fully impact CRC screening, but several key points should be considered moving forward. It is currently unclear whether or not insurance companies will begin to cover CRC screening tests for average-risk people between the ages of 45 to 49 years based on this guideline. Therefore, it would be advisable that the health care practitioner contact the patient’s insurance provider prior to undergoing a screening test to avoid potentially high costs (or advise their patient to do so). Assuming structural tests will be covered by insurance for this age range, the access to facilities and physicians that perform them could become a concern, though there have been preliminary studies suggesting that access to colonoscopies should not be an issue in the United States.⁶It will also be interesting to see how the other societies, such as the American College of Gastroenterology (ACG), American Gastroenterological Association (AGA), and United States Preventive Services Task Force (USPSTF), react to the ACS guidelines and whether or not they follow suit by lowering the screening age in their respective guidelines. 

Other key points from the recent ACS guidelines include the definition of “average risk” persons as those without a family history of CRC, personal history of CRC or polyps, personal history of inflammatory bowel disease (Crohn’s disease or ulcerative colitis), a confirmed or potential hereditary CRC syndrome (eg, Lynch Syndrome), or a personal history of undergoing radiation to the abdomen or pelvis for prior cancer treatment. 

The ACS guidelines provide several options for CRC screening, including stool-based tests and structural examinations. Stool-based tests include fecal immunochemical test (FIT) every year, high-sensitivity guaiac-based fecal occult blood test every year, or multi-target stool DNA test every 3 years. Structural exams include colonoscopy every 10 years, CT colonography every 5 years, or flexible sigmoidoscopy every 5 years. It is recommended that any “positive” test outside of colonoscopy is followed up with a colonoscopy. This is an important discussion point to have with the patient so that he or she understands all of the implications of the test. 

Additional age-specific recommendations from the ACS guidelines update include continuing regular CRC screening through the age of 75 years as long as the person has a life expectancy of more than 10 years. The decision to continue screening between the ages of 76 and 85 years is based on many factors including life expectancy, patient preference, and the person’s overall health. ACS recommends against CRC screening in people older than 85. 

References

1. Wolf AMD, Fontham ETH, Church TR, et al.Colorectal cancer screening for average-risk adults: 2018 guideline update from the American Cancer Society[published online May 30, 2018]. CA Cancer J Clin.doi: 10.3322/caac.21457 
2. O’Connell JB, Maggard MA, Liu JH, et al.Rates of colon and rectal cancers are increasing in young adults. Am Surg.2003;69(10):866-872.
3. Bailey CE, Hu C-Y, You YN, et al. Increasing disparities in the age-related incidences of colon and rectal cancers in the Unites States, 1975-2010. JAMA Surg.2015;150:17-22.
4. Siegel RL, Miller KD, Fedewa SA, et al. Colorectal cancer incidence patterns in the United States, 1974-2013. J Natl Cancer Inst.2017;109(8). doi: 10.1093/jnci/djw322
5. Lieberman DA, Holub JL, Moravec MD, et al. Prevalence of colon polyps detected by colonoscopy screening in asymptomatic black and white patients. JAMA. 2008;300:1417-1422.
6. Joseph DA, Meester RG, Zauber AG, et al. Colorectal cancer screening: estimated future colonoscopy need and current volume and capacity. Cancer. 2016;122:2479-2486.