Feasibility and Compliance of Stool Collection for Future Microbiome-Based Colorectal Cancer Screening: Preliminary Findings from a Prospective Multicenter FIT-Positive Cohort.

Colorectal cancer (CRC) remains a major global health burden, and early detection through population-based screening programs significantly reduces both incidence and mortality. Although gut microbiome-based biomarkers have emerged as promising non-invasive tools for CRC detection, limited evidence is available regarding patient acceptance and compliance with microbiome-based screening studies, factors that may influence their future implementation in clinical practice. We conducted a preliminary analysis of an ongoing multicenter, prospective observational study designed to develop a gut microbiome-based diagnostic tool for CRC and advanced colorectal adenomas in fecal immunochemical test (FIT)-positive individuals. The primary objective of this preliminary analysis was to evaluate patient acceptance and compliance with participation in a microbiome-based study within an organized CRC screening setting. Secondary objectives included describing the clinical, endoscopic, and histopathological characteristics of the enrolled cohort. FIT-positive individuals referred for screening colonoscopy at participating Italian centers were screened for eligibility, underwent colonoscopy, and were invited to provide a stool sample for microbiome analysis. A total of 315 individuals were screened, of whom 212 (67%) were enrolled. Among eligible patients, 90% agreed to enroll after receiving study information. Overall, 200 (94%) of enrolled individuals completed the required study activities, including stool sample collection and colonoscopy, indicating high compliance with study procedures. Colonoscopy was performed in 209 patients (99% of enrolled patients). CRC was detected in 7 patients (3%), and advanced colorectal adenomas in 39 (18%), while 86 (41%) colonoscopies were negative. The positive predictive value of FIT was 3.35% for CRC and 18.66% for advanced adenomas. In our preliminary analysis, patient acceptance and compliance with microbiome-based sampling were high among FIT-positive individuals undergoing CRC screening. These findings support the feasibility of conducting microbiome-based studies within organized screening programs. Analyses aimed at developing and validating the microbiome-based diagnostic tool are currently ongoing and are beyond the scope of the present report.