Pancreatic cancer biomarkers and diagnostic tools (Review)

Pancreatic ductal adenocarcinoma (PDAC) is characterized by late presentation, early systemic dissemination and profound therapeutic resistance.Biomarkers are therefore required not only for early detection, but also for prognosis, treatment selection and longitudinal monitoring.The present review summarizes established and emerging PDAC biomarkers across genomics, epigenomics, transcriptomics, proteomics, metabolomics and liquid biopsy.Particular attention is given to predictive biomarkers for personalized systemic therapy, including homologous-recombination repair defects associated with platinum sensitivity and eligibility for maintenance olaparib, as well as investigational markers of response to gemcitabine, fluoropyrimidines, irinotecan and oxaliplatin.The evolving role of companion diagnostics for germline BRCA1/2 variants and tumor-agnostic alterations is also discussed.In addition, the present review discusses biomarkers associated with occult or distant metastasis, including circulating tumor DNA, circulating tumor cells, extracellular vesicles, the SMAD4 status and multi-modal radiomic models.CA19-9 remains the most commonly used serum marker; however, it is unsuitable for population screening and cannot independently establish diagnosis or metastatic risk.The majority of multi-omics candidates remain at the discovery or retrospective-validation stage.Their clinical translation requires analytically standardized assays, prospective validation in defined clinical settings and evidence that biomarker-guided decisions improve patient outcomes.Contents 1. Introduction 2. Current diagnostic framework and unmet needs 3. Biomarkers for detection, prognosis and monitoring 4. Predictive biomarkers for personalized systemic therapy and companion diagnostics 5. Biomarkers for distant metastasis and early systemic dissemination 6. Tissue, extracellular vesicles and multi-modal signatures 7. Clinical-readiness matrix 8. Translational challenges and future directions 9.