Differential Plasma Expression of sTNF-R, TNF-α, PDGF-AA, IL-17A, and IL-1β Across the Colorectal Neoplasia Spectrum

Colorectal cancer (CRC) remains one of the most important causes of cancer-related mortality worldwide, underscoring the need to better understand systemic inflammatory pathways across the colorectal neoplasia spectrum. In this exploratory case-control study, we characterized plasma levels of key inflammatory mediators in healthy individuals and patients with colorectal polyps or CRC. Healthy controls (n = 10), patients with colorectal polyps (CP, n = 16), early-onset CRC (EO-CRC, n = 11), and late-onset CRC (LO-CRC, n = 51) were prospectively enrolled. Plasma levels of sTNF-R, total TNF-α, PDGF-AA, IL-17A, and IL-1β were measured by ELISA. Group comparisons used Kruskal-Wallis tests with epsilon-squared effect sizes. PDGF-AA showed the strongest differences between controls and all neoplastic groups (ε² ≥ 0.15), and these comparisons remained significant after Benjamini-Hochberg false discovery rate correction. IL-17A levels were slightly higher in EO-CRC than in LO-CRC; however, this difference did not remain significant after adjustment for multiple testing. TNF-α and IL-1β showed no significant differences across groups. Overall, this study primarily provides descriptive and hypothesis-generating evidence of differential inflammatory patterns across colorectal neoplasia, with PDGF-AA emerging as the most robust signal in this exploratory dataset. These findings do not support immediate diagnostic application and require validation in larger, prospectively recruited cohorts.