In the search for biomarkers that may prove useful in the differential diagnosis of benign cystic pancreatic tumors and PDAC, we have found that lower PDGF-AB/BB and leptin concentrations in serum were associated with cancer, and lower concentrations of sTIE-2, osteopontin, and leptin in the cystic fluid may be associated with cancerous tumors. This evidence concerns the gene SPP1 and cancer.