Stool-Based DNA Testing Leads to Timely Colonoscopy in Rural, Urban Populations

Colorectal cancer (CRC) remains a leading cause of cancer deaths in the US, yet many patients delay colonoscopy due to hesitancy and long wait times.¹ However, a new study shows stool-based DNA testing offers timely follow-up for both rural and urban patients, supporting its role in expanding equitable CRC screening.

This observational case-control study is published in The American Surgeon.

“With medical resources becoming increasingly stretched across the United States, patients often face long waits to receive colonoscopies,” wrote the researchers of the study. “Long follow-up intervals after stool-based testing could further exacerbate health disparities in rural patients who already face significant barriers to health care. The aim of this study was to evaluate our institution’s time from a positive stool-based DNA test to the completion of a diagnostic colonoscopy in both rural and non-rural populations.”

Rural-urban disparities in CRC screening persist across the US.² Differences in education, income, insurance coverage, and provider access contribute to this gap. However, much remains unexplained, pointing to deeper structural, cultural, and systemic barriers, underscoring the need for equity-focused interventions to improve screening uptake and reduce preventable CRC mortality in rural communities.

The study included patients 18 years or older who had a positive DNA-based stool test and subsequently underwent diagnostic colonoscopy between January 2018 and December 2023 at a single health system in the Midwest US.¹ Participants were categorized as rural or nonrural based on Rural-Urban Commuting Area codes. The primary outcome measured was the time, in days, from a positive stool-based test to completion of diagnostic colonoscopy.

Of the 1316 patients included in the study, 668 (50.8%) were classified as rural. The median time to diagnostic colonoscopy was similar between groups, with rural patients undergoing colonoscopy in 35 days compared with 37 days for nonrural patients (P = .6). There was no statistically significant difference in follow-up times between rural and nonrural populations. However, rural patients were significantly more likely to have their colonoscopy performed at an external facility (25% vs 3.1%; P < .001), highlighting differences in care settings despite comparable timeliness.

However, the researchers noted several limitations. First, it relied on recorded data, which may have limited accuracy. Second, it only focused on patients who completed stool-based DNA testing and colonoscopy, excluding those who did not undergo testing or follow-up. The study also did not assess outcomes for patients with negative stool-based tests or those who never completed colonoscopy, which the researchers acknowledged could provide valuable insights for improving CRC screening and reducing health inequities.

Despite these limitations, the researchers believe the study adds context of the value of stool-based DNA testing to increase screening and reduce the health burden of CRC among both rural and nonrural patients.

“With all patients receiving colonoscopy in our system, patients had an average wait time of 1 year from initial contact to colonoscopy,” wrote the researchers. “It is also more accessible for many patients and helps stratify low-risk individuals, identifying those who require diagnostic colonoscopy vs. those who can be adequately monitored with stool-based testing alone. At our institution, this study supports plans to utilize stool-based testing for all low-risk patients moving forward.”

References

1. Duncan AJ, Baden GH, Zukanovic S, et al. Timely follow-up after positive stool-based testing: evaluating diagnostic colonoscopy delays in rural and non-rural populations. Am Surg. 2025;31348251385107. doi:10.1177/00031348251385107

2. Steinzor P. Rural-urban disparities in colorectal cancer screening persist. AJMC^®. September 21, 2025. Accessed October 6, 2025. https://www.ajmc.com/view/rural-urban-disparities-in-colorectal-cancer-screening-persist