Elevated tumour marker CA19-9: clinical interpretation and influence of obstructive jaundice.
OBJECTIVE
The tumour marker CA19-9 has been promoted as a reliable test for the detection of pancreatobiliary malignancy, yet its diagnostic role remains poorly defined. In this study the clinical interpretation of a raised serum CA19-9 level has been evaluated, with particular reference to obstructive jaundice.


METHODS
One hundred and sixty-four patients with a CA19-9 level above 33 U/ml were studied. Serum CA19-9 was compared with clinical diagnosis and correlated with serum bilirubin level. In a subgroup of jaundiced patients (16 benign and 15 malignant cases), follow-up CA19-9 levels were determined 2 weeks after biliary drainage.


RESULTS
The median CA19-9 level was lower in benign cases (102 (IQR 50-264) U/ml) than those with pancreatobiliary tumours (910 (IQR 263-6170) U/ml; P<0.01), although the overlap was substantial. In benign jaundiced cases, a positive correlation was observed between bilirubin and CA19-9 elevation (R=0.41, P<0.01). Relief of jaundice was associated with a fall in CA19-9 level in all benign cases and in nine of the 15 with malignancy.


CONCLUSIONS
Confident discrimination between benign and malignant disease could not be made on the basis of a solitary elevated CA19-9 measurement. Hyperbilirubinaemia was associated with a further deterioration in specificity and caution is warranted when interpreting the results in jaundiced patients. Overall, only one half of patients with an elevated CA19-9 level ultimately proved to harbour a malignancy.
Mann
D V
DV
Department of Surgery, St Mary's Hospital, London, UK.
Edwards
R
R
Ho
S
S
Lau
W Y
WY
Glazer
G
G
D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001661:Biliary Tract Neoplasms / Q000097:blood / Q000150:complications / Q000175:diagnosis* / Q000276:immunology; D001663:Bilirubin / Q000097:blood; D014408:Biomarkers, Tumor / Q000097:blood*; D018395:CA-19-9 Antigen / Q000097:blood*; D002779:Cholestasis / Q000097:blood / Q000209:etiology* / Q000276:immunology; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000097:blood / Q000150:complications / Q000175:diagnosis* / Q000276:immunology; D011237:Predictive Value of Tests
D014408:Biomarkers, Tumor; D018395:CA-19-9 Antigen; D001663:Bilirubin