Elevated serum level of carbohydrate antigen 19-9 in benign biliary stricture diseases can reduce its value as a tumor marker.

Although carbohydrate antigen (CA19-9) level is frequently upregulated in pancreatobiliary cancer, it is also elevated in some benign diseases. This study aimed to determine whether CA19-9 levels could be used to distinguish between benign obstructive jaundice and pancreatobiliary cancer. Fifty-seven patients with obstructive jaundice were studied retrospectively. Endoscopic retrograde cholangiopancreatography (ERCP), sphincterotomy, stone extraction, or stent placement were used to treat patients with benign bile duct stricture or inoperable malignant biliopancreatic diseases, whilst surgery was performed in suitable cases. Serum CA19-9 levels and some additional biochemical parameters were evaluated before and after treatment. CA19-9 levels were elevated in most patients, along with levels of total bilirubin, alkaline phosphatase (ALP), and gamma glutamyl transpeptidase (GGT), and 10 patients with benign disorders had extraordinarily high levels of these markers (> 1000 U/mL). The mean CA19-9 level in the malignant group was greater than that in the benign group (826.83 ± 557.34 vs. 401.92 ± 483.92 U/mL, P = 0.005), and the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for CA19-9 were 100%, 7.69%, 33.33% and 47.47%, respectively. CA19-9 levels in the whole cohort were correlated with ALP (r = 0.77, P < 0.001), GGT (r = 0.83, P < 0.001), bilirubin (r = 0.69, P < 0.001), and CRP (r = 0.37, P = 0.004). The reduction in serum level of CA19-9 after treatment in the malignant group was remarkably less than that observed in the benign group (97.26 ± 123.24 U/mL vs. 352.71 ± 397.29 U/mL, P < 0.001). CA19-9 levels may not be sufficient to distinguish between malignant and benign obstructive jaundice diseases.