Elevation of Carbohydrate Antigen 19.9 in Benign Hepatobiliary Conditions and Its Correlation with Serum Bilirubin Concentration

Background Carbohydrate antigen 19.9 (CA19.9), a tumor marker for malignancies of the hepatobiliary tract and pancreas, has frequently been shown to be deranged in a number of non-malignant conditions that are associated with jaundice. This study aims to demonstrate the correlation between CA19.9 and serum bilirubin concentration in patients with benign conditions and to determine the frequency of a false-positive increase in CA19.9 in patients being investigated for potential HPB malignancies. Methods This is a retrospective review of 83 consecutive patients presenting with an abnormal CA19.9 and radiological or clinical features suggestive of HPB malignancy subsequently shown to have benign disease. All patients were thoroughly investigated and followed up until the diagnosis of malignancy could be safely excluded. Results Serum bilirubin, sodium, lymphocyte count, neutrophil:lymphocyte ratio (NLR), beta-human chorionic gonadotrophin (HCG), and age were found to correlate with CA19.9 by Pearson's correlation (P = 0.001, P = 0.006, P = 0.006, P < 0.001, P = 0.012, and P = 0.049, respectively). In multivariate regression analysis, bilirubin was identified as an independent variable that may predict CA19.9 level (P = 0.028). Conclusion CA19.9 level is significantly influenced by serum bilirubin and elevated levels have been observed in patients with non-malignant HPB conditions. Adjusting CA19.9 according to bilirubin levels is likely to improve the specificity of this antigen in the differential diagnosis of benign and malignant HPB diseases and its reliability in the monitoring of disease response to chemotherapy.