Repeat mt-sDNA Screening for Colorectal Cancer in Underserved Populations

Repeat mt-sDNA Screening Demonstrates Strong Adherence in Underserved Populations

Ensuring consistent colorectal cancer (CRC) screening adherence is a critical public health goal, especially in Federally Qualified Health Centers (FQHCs), where socioeconomic and systemic barriers challenge preventive care. A new real-world analysis published in Journal of Primary Care & Community Health in June of 2025 offers the most robust evidence to date on repeat screening behavior using multi-target stool DNA (mt-sDNA) testing in this underserved setting, showing notably high adherence rates and key demographic predictors. Here’s a breakdown of the study and its findings.

National Scope, Equity Focus by Design

This retrospective cohort study examined 19,536 adults aged 45 to 85 who previously completed a negative mt-sDNA test and were prescribed a repeat test through an FQHC in 2023. Adherence was defined as returning a valid test kit within 180 days of shipment. The de-identified dataset, drawn from Exact Sciences Laboratories, included breakdowns by insurance, race, urban/rural status, income, and communication channels.

High Overall Adherence with Key Disparities

Looking at the findings, the study found the following:

• Overall repeat screening adherence was 79.7 percent, surpassing rates commonly observed with fecal immunochemical testing (FIT), where second-round adherence often drops below 50 percent.
• Patients with Medicare had the highest adherence at 84.7 percent, while those on Medicaid had the lowest at 65.9 percent.
• Those with two or more prior successful mt-sDNA tests were significantly more adherent than those with only one prior test, at 90.8 and 79.3 percent respectively.

• Full digital outreach with both email and SMS resulted in the highest adherence—84.1 percent—in comparison to communication with patients via standard methods only, such as phone calls and letters, which resulted in 72.9 percent adherence. Patients receiving full digital outreach were twice as likely to be adherent as those receiving no digital messaging (OR 2.07, 95 percent CI 1.86–2.30).

Socioeconomic and Geographic Trends

Income, geographic setting, and social vulnerability emerged as meaningful predictors, showing that:

• Residents in ZIP codes with median household incomes under 50,000 dollars had the lowest adherence at 75.6 percent, while those in the 50,000-to-125,000-dollar range showed 80 to 82 percent adherence.
• Medicaid beneficiaries had 42 percent lower odds of adherence compared to commercially insured patients (OR 0.582, 95 percent CI 0.461–0.733).
• Surprisingly, micropolitan and rural residents showed higher adherence than those in metropolitan areas—an inversion of typical CRC screening patterns and possibly reflective of enhanced outreach or community trust in FQHC-based interventions.

Time to Return: Another Dimension of Engagement

While adherence was high, time to test return varied. The study found that:

• Overall average time to test return was 21.1 days.
• Patients with two or more prior successful tests returned kits more quickly than those with just one prior test, at 16.7 days and 21.3 days respectively.
• Medicaid patients had the slowest return times at approximately 24 days, while Medicare patients returned kits fastest at around 20 days.

A Model for Sustainable Screening

These findings support mt-sDNA as a viable and scalable strategy for sustained CRC screening adherence in vulnerable populations—an urgent need as guidelines expand and disparities widen. While repeat screening rates exceeded expectations, persistent gaps remain. Digital outreach, longitudinal engagement, and payer type emerge as modifiable levers for programmatic improvement.

Reference:

1. Greene M, Pew T, Zapatier J, Rincón López JV, Limburg P, Duarte M. Adherence to repeat screening completion for colorectal cancer using the multi-target stool DNA test: real-world analysis of patients from federally qualified health centers. J Prim Care Community Health. 2025;16:1-10. doi:10.1177/21501319251348099.