CA 19-9 in combination with abdominal CT scan for the diagnosis of mass-forming intrahepatic cholangiocarcinoma.

Aim: Cholangiocarcinoma (CCA) is a common form of cancer in Thailand. The diagnosis of CCA by pathology is widely accepted. Unfortunately, tissue diagnosis of mass-forming intrahepatic cholangiocarcinoma is difficult to perform due to the risk of the procedure and accessibility. The aim of this study is to assess the diagnostic utility of CA19-9 in combination with CT scan for the diagnosis of mass-forming cholangiocarcinoma.

Materials & Methods: The medical records of patients with a diagnosis of CCA and hepatocellular carcinoma (HCC) during January 2005-December 2009 were reviewed. Only cases with pathology and CT scan reports from Maharaj Nakorn Chiang Mai Hospital were included. Demographic data, clinical manifestations and laboratory results, including CA19-9 and CT scans of the liver, were carefully examined in order to establish their diagnostic utility in mass-forming CCA without a pathological diagnosis.

Results: A total of 79 CCA patients and 66 HCC patients were included in CA19-9 cut-off level analyses. A total of 31 CCA patients and 44 HCC patients were included in the CT scan evaluation and scored according to the Chiang Mai CT score for CCA. The specificity of a CA19-9 value of 500 U/ml for the diagnosis of CCA was 95.5% with a sensitivity of 50.6%, positive predictive value of 91.8% and likelihood ratio of positive (LR+) of 11.24. A CT score greater than 2 demonstrates a positive predictive value of more than 90% in diagnosis of CCA. The CA19-9 level of 140 U/ml in combination with a CT score of 2 demonstrated LR+ as high as 57.09. A CA19-9 level of 280 U/ml in combination with a CT score of 1 demonstrated LR+ of 58.4.

Conclusion: A CA19-9 level combined with the Chiang Mai CT score for CCA are good diagnostic tools for the diagnosis of mass-forming cholangiocarcinoma with high specificity, high positive predictive value and high likelihood ratio of positive.