Abstract
<title>Abstract</title> <p> <bold>Background:</bold> Colon cancer (CC) and pancreatic ductal adenocarcinoma (PDAC) remain major causes of cancer mortality due to limitations in early detection and risk stratification. Cancer-associated fibroblasts (CAFs) and stromal remodeling represent underexplored sources of clinically relevant circulating biomarkers in gastrointestinal malignancies. <bold>Methods:</bold> Building on our previous characterization of CAF-derived extracellular vesicle (EV) cargo, we evaluated three stromal-associated small non-coding RNAs (sncRNAs; two snRNAs and one piRNA) as proof-of-concept EV-associated biomarkers in pre-operative peripheral blood. EV-enriched fraction RNA was isolated from serum samples of patients with benign, premalignant, and malignant colon lesions, PDAC patients, and healthy donors. sncRNA expression was quantified by RT–qPCR. Predictive modeling assessed diagnostic and prognostic performance, and the biological relevance of the associated stromal programs was investigated through analysis of predicted sncRNA target genes in a TCGA colon cancer cohort. <bold>Results:</bold> The stromal-associated sncRNA panel discriminated CC patients from healthy individuals (AUC = 0.778) and identified benign and premalignant colonic lesions (AUC = 0.804). In PDAC, the same signature achieved comparable diagnostic performance (AUC = 0.775), while combined CC/PDAC analysis yielded an AUC of 0.772, supporting the detection of stromal-derived circulating signals across two major gastrointestinal malignancies. In stage I–III CC patients, pre-operative sncRNA levels showed modest prognostic performance for relapse prediction (AUC = 0.561) and were independently associated with relapse risk in multivariable Cox regression analysis. Analysis of 43 predicted target genes in a TCGA cohort of 597 CC patients revealed strong associations with overall survival (AUC = 0.807; log-rank <italic>p</italic> < 0.001). <bold>Conclusions:</bold> These findings demonstrate that stromal-associated EV sncRNAs can be detected in peripheral blood and provide clinically informative signals for diagnostic classification and exploratory risk stratification in gastrointestinal malignancies. By capturing tumor stroma–associated biology through a minimally invasive liquid biopsy, these biomarkers complement conventional tumor cell-centered approaches and support the tumor stroma as a promising source of circulating biomarkers for future translational studies. </p>