Serum IL-17A as a Diagnostic and Prognostic Biomarker in Colorectal Cancer: Development and Validation of a Multi-Indicator Model

Objective: Colorectal cancer ranks as the third most prevalent malignancy globally. To address the limited sensitivity of conventional biomarkers, this study evaluated the clinical utility of preoperative serum interleukin-17A (IL-17A) in CRC diagnosis and prognosis. We aimed to develop a multi-indicator diagnostic model and assess its prognostic efficacy.Methods: This study involved 126 patients diagnosed with colorectal cancer (CRC) who underwent radical resection at the First Affiliated Hospital of Chongqing Medical University between June 2022 and December 2023. Additionally, a control group was established, consisting of 28 patients diagnosed with colorectal adenoma and 27 healthy volunteers. Clinical parameters included age, sex, tumor stage, CEA, CA199, and IL-17A. Optimal IL-17A cutoff values were determined using X-tile software. A combined diagnostic model (IL-17A + CEA + CA199) was developed, and its performance was evaluated via receiver operating characteristic (ROC) analysis. Cox regression and Kaplan-Meier survival analyses identified prognostic factors.Results: Serum IL-17A levels were significantly higher in the CRC group compared to the healthy control group (10.0 pg/mL vs 7.1 pg/mL, P = 0.034) and positively correlated with vascular invasion (P = 0.027). The IL-17A-CEA-CA199 combined diagnostic model demonstrated superior diagnostic accuracy compared to single indices such as CEA (AUC=0.754 vs 0.704, P = 0.001) and CA199 (AUC=0.587). Multivariate analysis revealed that elevated IL-17A levels were associated with prolonged OS (HR=0.26, 95%CI 0.08-0.81, P = 0.022), and IL-17A was identified as an independent protective factor for OS (P =0.032). Conclusion: The IL-17A-CEA-CA199 diagnostic model enhances the sensitivity of early CRC diagnosis, and IL-17A serves as an independent prognostic marker for CRC. This study validates the role of IL-17A in both early diagnosis and prognosis prediction of CRC, offering novel insights for optimizing CRC screening strategies and personalized treatment approaches.