Clinical discrimination between choledocholithiasis and biliopancreatic malignancy based on a new biochemical model.

Purpose: This study aims to establish predictive laboratory tests, which could confidently assist for an initial clinical discrimination of choledocholithiasis from biliopancreatic malignancy, before an invasive endoscopic or surgical diagnosis. Results: A total of 174 patients, who underwent ERCP were analyzed. Patients with final diagnosis of choledocholithiasis (137 patients) and biliopancreatic adenocarcinoma (37 patients) had their biochemistry parameters compared using Mann-Whittney test. Cut-off values for each parameter were defined. The cut-off values that provided the best trade-off between sensitivity and specificity were: 8.65 mg/ dL for total bilirubin, 276 U/L for serum alkaline phosphatase and 306 IU/ml for CA19-9. A patient most probably (96%) suffers from cancer, if he has high incriminating values in all these three parameters. Conclusions: A simple, reproducible, easy-to-obtain predictive model with laboratory tests, successfully differentiates choledocholithiasis from malignant biliopancreatic diseases and could be useful for a more cost-effective investigation and treatment of patients with such pathology.