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Home  >  Medical Research Archives  >  Issue 149  > Colorectal Cancer Screening: What Do We Need to Build and Who Will Come?
Published in the Medical Research Archives
Jun 2023 Issue

Colorectal Cancer Screening: What Do We Need to Build and Who Will Come?

Published on Jun 26, 2023




Approximately one third of screen eligible individuals in the US are due or overdue for colorectal cancer (CRC) screening. The burden of screening is compounded by the addition of younger individuals to the screening pools and disruption in screening activities due to the pandemic. Colonoscopy is the most commonly used screening modality. However, role of non-invasive CRC screening tests needs to expand to meet the demands for screening. The current models of opportunistic screening fail to meet the population adherence of 80% or higher, and may worsen healthcare disparities. In the post-pandemic landscape, it is important for healthcare systems, clinics and organizations to adopt population based programmatic approaches to improve adherence to colorectal cancer screening and ensure this is done in a framework that ensure health equity.

Author info

Aasma Shaukat, Jeffrey Lee, Theodore Levin

Recent guidelines by the ACG, US Multi-Society Task Force, US Preventive Services Task Force and American Cancer Society are all in consensus and have lowered the starting age for CRC screening from 50 to 451, 2, adding an additional twenty million newly eligible men and women to the screening pool. While epidemiologic and modelling data support lowering the CRC screening age,3, 4 it will put pressure on the US healthcare system already strained by the COVID-19 pandemic. Pre- pandemic, CRC screening rates among those aged 50 and older were 67%.5 The pandemic largely halted screening efforts for most of 2020, and with the resumption of screening, most healthcare systems are still trying to catch up. Hence there is an unmet need to expand CRC screening capacity.

Population based approaches are needed:
In the US, colonoscopy is the most widely used modality for CRC screening.6 However, we cannot rely solely on colonoscopy screening to meet these needs. The effect of the pandemic, influx of newly screening-eligible adults 45-49 years of age, and the existing high demand for diagnostic and surveillance colonoscopies have all contributed to the currently strained colonoscopy capacity. As gastroenterologists, we should realize that fully booked endoscopy centers may not mean that individuals that are most likely to benefit are undergoing CRC screening. A broader, population health view of the screen eligible population suggests that rather than focusing on promoting screening colonoscopies for those with easy access and interest, we can achieve a greater public health benefit by identifying those who remain unscreened or not up-to-date with current screening recommendations and delivering CRC screening equitably.

Strategies to achieve higher adherence:
One strategy to promote equitable screening is to expand availability of noninvasive screening tests and offer them in a programmatic approach. Stool based testing with fecal occult blood or fecal immunochemical testing (FIT) reduces CRC incidence and mortality in clinical trials and in organized screening programs.7-10 Offering a choice of stool- based screening tests (e.g.,FIT) in randomized trials have consistently led to higher acceptance for CRC screening invitation and screening completion. Additionally, a recently passed bill has closed the loophole for Medicare beneficiaries, wherein the diagnostic colonoscopy for a positive FIT has no cost sharing, reducing the financial burden of this option. It is a common misconception that screening colonoscopy benefits everyone. The primary benefit of colonoscopy is detection of colorectal cancer and advanced neoplasia, which is found in <1% and 10% of those undergoing screening.9-11 In the 30- 50% of individuals where no cancer or polyps are found, colonoscopy does not provide any added value other than reassurance, but exposes individuals to potential risks of the preparation, anesthesia and procedure itself. In contrast, a non- invasive screening test can help with risk stratification, by identifying individuals who are more likely to have advanced polyps and cancer and reduce the harmful risks from colonoscopy.

Improving adherence increases colonoscopy volume over time:
Many US gastroenterologists have resisted efforts to increase FIT screening out of concern that people will opt for FIT instead of colonoscopy, foregoing colonoscopy which they feel is superior to FIT. It’s important to realize that the addition of these tests will not reduce the demand for colonoscopy but likely increase it over time, and shift the indication to more diagnostic and surveillance exams. Consider this back-of-the-envelope calculation: Of the 100.3 million individuals in the US that are 50- 75 years old, approximately 33 million (33%) are not screened, plus 20 million added 45-49 year olds (total 55 million). If we offered them colonoscopy screening only, the uptake will be approximately 30% (ref), i.e. 15 million colonoscopies, which will require us to nearly double our current colonoscopy capacity. Most of these individuals will be screen eligible again in 10 years. However if we offered a FIT, and administered it programmatically, we may achieve 80% adherence, i.e. 40 million screened. At a positivity rate of 5%, that would require 2 million diagnostic colonoscopies. Since FIT needs to be repeated yearly, and assuming that 80% of the 40 million (excluding screened but including the newly eligible) adhere, that would generate 2 million colonoscopies every year for next 10 years, i.e. 20 million over 10 years. Not only do we achieve higher screening rates, we generate more colonoscopies, especially diagnostic ones, where yield of neoplasia is higher.

With several new stool- and blood-based CRC screening tests now available or close to being available, now is the optimal time to expand our CRC screening approach and build organized screening programs using noninvasive testing for the health of our populations.

1.    Shaukat A, Kahi CJ, Burke CA, et al. ACG Clinical Guidelines: Colorectal Cancer Screening 2021. Am J Gastroenterol 2021;116:458-479.
2.    Force USPST, Davidson KW, Barry MJ, et al. Screening for Colorectal Cancer: US Preventive Services Task Force Recommendation Statement. JAMA 2021;325:1965-1977.
3.    Siegel RL, Miller KD, Goding Sauer A, et al. Colorectal cancer statistics, 2020. CA Cancer J Clin 2020;70:145-164.
4.    Siegel RL, Torre LA, Soerjomataram I, et al. Global patterns and trends in colorectal cancer incidence in young adults. Gut 2019;68:2179-2185.
5.    Fedewa SA, Sauer AG, Siegel RL, et al. Temporal Trends in Colorectal Cancer Screening among Asian Americans. Cancer Epidemiol Biomarkers Prev 2016;25:995- 1000.
6.    Fisher DA, Princic N, Miller-Wilson LA, et al. Utilization of a Colorectal Cancer Screening Test Among Individuals With Average Risk. JAMA Netw Open 2021;4:e2122269.
7.    Shaukat A, Church TR, Mandel JS. Guaiac Fecal Occult Blood Test and Reduction in Colorectal Cancer Incidence. Clin Gastroenterol Hepatol 2021;19:2217.
8.    Shaukat A, Kaalby L, Baatrup G, et al. Effects of Screening Compliance on Long- term Reductions in All-Cause and Colorectal Cancer Mortality. Clin Gastroenterol Hepatol 2021;19:967-975 e2.
9.    Levin TR, Corley DA, Jensen CD, et al. Effects of Organized Colorectal Cancer Screening on Cancer Incidence and Mortality in a Large Community-Based Population.    Gastroenterology 2018;155:1383-1391 e5.
10.    Selby K, Jensen CD, Levin TR, et al. Program Components and Results From an Organized Colorectal Cancer Screening Program Using  Annual  Fecal Immunochemical Testing. Clin Gastroenterol Hepatol 2022;20:145-152.
11.    Shaukat A, Marsh TL, Crockett SD, et al. Low Prevalence of Screen-Detected Colorectal Cancer in an Average-Risk Population: The New Normal. Clin Gastroenterol Hepatol 2021.

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