Mark Fendrick, MD, is a professor and director of the Center for Value-Based Insurance Design at the University of Michigan.

Mark Fendrick, MD

The Environmental Impact of Colorectal Cancer Screening, with Mark Fendrick, MD

Health systems are increasingly being recognized as a major contributor to the growing threat of climate change, with greenhouse gas emissions in this sector increasing by 36% since 2016 and accounting for approximately 4.6% of global emissions in 2021.

In order to reduce medical care delivery–related carbon effects, quantifying the environmental impact of specific clinical services and prioritizing lower-carbon alternatives will be essential, especially in scenarios for which multiple options are recommended by evidence-based guidelines, including colorectal cancer screening.

Research presented at Digestive Disease Week (DDW) 2025 explored the environmental impact of decennial colonoscopy and triennial multi-target stool DNA (mt-sDNA) testing, both of which are recommended for average-risk individuals and detect > 90% of colorectal cancer cases.

Regarding the choices available to patients for colorectal cancer screening, Mark Fendrick, MD, professor and director of the Center for Value-Based Insurance Design at the University of Michigan, told 

 that while many people look at whether or not they can complete the test at home, how far they have to travel, and what they have to pay out of pocket, patients are increasingly seeking a green option.

In his research presented at DDW, Fendrick and colleagues simulated a cohort of 1 million average-risk individuals undergoing either triennial mt-sDNA or decennial colonoscopy screening using the validated CRC-AIM microsimulation model. They found CO2e attributed to screening colonoscopy was 59% and 269% higher than mt-sDNA under lifetime and one-time screening scenarios, respectively, and noted most emissions incurred by the mt-sDNA strategies were attributable to follow-up colonoscopy after a positive mt-sDNA result (64% for lifetime and 74% for one-time screening).

For colonoscopy strategies, more than 41% of CO2e was attributed to transportation, while for mt-sDNA, more than 42% of CO2e was attributed to transportation, including travel to colonoscopy and shipping of mt-sDNA tests.

“Our research shows, maybe not surprisingly, that the home based stool DNA test had a remarkably lower carbon footprint compared to screening colonoscopy,” Fendrick explained, further describing how the majority of the carbon footprint related to stool DNA testing was attributable to follow-up colonoscopy. “There's lots of reasons why individuals and their clinicians might pick a particular modality, but if you were on the fence and you had environmental impact reduction as one of the things that was meaningful to you as an individual, I think it was very important for us to point out that compared to screening colonoscopy, stool DNA is the greener option.”

Fendrick goes on to describe the importance of increasing efforts to reduce screening colonoscopies and conduct more stool-based testing in order to feasibly screen the entire population, citing other research he presented at DDW demonstrating an advantage of follow-up colonoscopy performance for those who undergo stool DNA testing compared to FIT.

However, he also calls attention to the Kennedy v Braidwood Supreme Court case challenging the provision in the Affordable Care Act that mandates private insurers and Medicare cover colorectal cancer screening at no cost to patients, describing the potential negative impact this could have on screening completion rates moving forward.

Romanello M, Walawender M, Hsu SC, et al. The 2024 report of the Lancet countdown on health and climate change: facing record-breaking threats from delayed action. 

Alcock R, Shaukat A, Kisiel JB, et al. THE ENVIRONMENTAL IMPACT OF COLORECTAL CANCER SCREENING WITH COLONOSCOPY AND MT-SDNA IN THE US: A SIMULATION STUDY. Abstract presented at Digestive Disease Week 2025 in San Diego, CA, from May 3 - May 6, 2025.

Fendrick M. Optimizing Follow-Up Colonoscopy Rates for CRC Screening, with Mark Fendrick, MD. 

https://www.hcplive.com/view/optimizing-follow-up-colonoscopy-rates-crc-screening-with-mark-fendrick-md

Videos

Fendrick describes patients’ desire for green screening options and reviews findings from a study comparing the environmental impact of screening tools.

Optimizing Follow-Up Colonoscopy Rates for CRC Screening, with Mark Fendrick, MD

New research is shedding light on differences in adherence to follow-up colonoscopy after a positive result on a noninvasive 

 screening test, with results suggesting the benefit of initial screening with a stool-based DNA test.

In 2021, the US Preventive Services Task Force lowered the recommended screening age from 50 to 45, vastly expanding the screening-eligible population.

Combined with a backlog from the COVID-19 pandemic and limited colonoscopy capacity, these factors have accelerated the push toward non-invasive testing options.

However, a follow-up colonoscopy is essential to complete the screening process when a noninvasive test yields a positive result.

“While not everyone who should be getting a follow up colonoscopy is getting them, we know that a significantly higher number of people are getting them,” Mark Fendrick, MD, professor and director of the Center for Value-Based Insurance Design at the University of Michigan, explained to 

, citing the benefits of recent federal regulations mandating no-cost follow-up colonoscopies for insured patients.

Fendrick goes on to describe research being presented at Digestive Disease Week (DDW) 2025 demonstrating greater rates of follow-up colonoscopy with stool DNA testing than with FIT. Specifically, the studies looked at this trend in the context of certain variables, including age, geographic location, and race, consistently demonstrating increased rates of follow-up colonoscopy with initial multitarget stool DNA testing than fecal immunochemical tests or fecal occult blood tests.

He credits much of the improved adherence to the robust patient navigation and educational support offered by manufacturers of stool DNA tests, which help address common barriers such as limited health literacy, confusion about the steps involved, and difficulty with scheduling or preparing for colonoscopy.

Looking ahead, Fendrick points to the promise stool DNA testing offers for helping to achieve the goals of minimizing the burden of colorectal cancer.

Editors’ note: Fendrick has relevant disclosures with AbbVie, Exact Sciences, Johnson & Johnson, Medtronic, MedZed, Merck, Phathom Pharmaceuticals, and others.

USPSTF. Final Recommendation Statement. Colorectal Cancer: Screening. May 18, 2021. Accessed May 4, 2025. 

https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/colorectal-cancer-screening

Greene M, Stieber B, Ozbay AB, et al. ADHERENCE TO FOLLOW-UP COLONOSCOPY AFTER POSITIVE STOOL-BASED SCREENING: EXAMINING DIFFERENCES BETWEEN MULTITARGET STOOL DNA TESTS VERSUS FECAL IMMUNOCHEMICAL OR FECAL OCCULT BLOOD TESTS IN RACIAL/ETHNIC SUBGROUPS. Abstract presented at DDW 2025 in San Diego, CA, from May 3 - May 6, 2025.

Greene M, Stieber B, Ozbay AB, et al. ADHERENCE TO FOLLOW-UP COLONOSCOPY AFTER A POSITIVE STOOL-BASED TEST PATIENTS AGED 45 TO 49 YEARS: REAL WORLD DIFFERENCES BETWEEN MULTITARGET STOOL DNA TESTING VERSUS FECAL IMMUNOCHEMICAL OR FECAL OCCULT BLOOD TESTING. Abstract presented at DDW 2025 in San Diego, CA, from May 3 - May 6, 2025.

Fendrick describes the importance of follow-up colonoscopy after a positive result on a noninvasive test and factors influencing follow-up rates.

Mark Fendrick, MD

Articles