SERUM DES-GAMMA-CARBOXYPROTHROMBIN CONCENTRATION DETERMINED BY THE AVIDIN-BIOTIN COMPLEX METHOD IN SMALL HEPATOCELLULAR CARCINOMAS

Background. Des-gamma-carboxyprothrombin (DCP) is a useful tumor marke r for hepatocellular carcinoma (HCC). The present method for measureme nt of DCP concentration, however, does not have adequate sensitivity t o detect small HCCs. Methods. The serum DCP concentration was investig ated by the avidin-biotin complex (ABC) method in patients with an HCC smaller than 20 mm in maximum dimension. A serum DCP concentration gr eater than 4.0 arbitrary units per liter using the ABC method was cons idered abnormal. Results. Of 115 patients with small HCC, 45 (39.1%) h ad an abnormal DCP concentration. Ten of 141 patients with chronic hep atitis (7.1%), 18 of 115 (15.7%) with cirrhosis, and 0 of 30 normal co ntrol patients had abnormal DCP concentrations. This method yielded a sensitivity of 39.1%, a specificity of 89.1%, a positive predictive va lue of 61.6%, and a negative predictive value of 76.5% for detection o f small HCC. The detectability of HCC increased to 56.5% when alpha-fe toprotein (AFP) was was measured (> 40 ng/ml). Abnormal DCP concentrat ions were seen in 8 of 34 (23.5%), 24 of 42 (57.1%), and 5 of 7 (71.4% ) patients with Edmondson's Grade I, II, and III tumors, respectively. There was a significant relationship between DCP concentrations and h istologic grade (P = 0.0017), but there was no association between DCP concentration and other patient characteristics. Elevation of serum A FP concentrations in patients with hepatitis B surface antigen positiv ity, however, was more frequent than that in patients who were antihep atitis C virus (HCV) positive. Therefore, the measurement of serum DCP concentrations may be more useful than that of serum AFP concentratio ns in patients with anti-HCV positivity. Conclusions. The measurement of serum DCP concentrations by the ABC method is a useful diagnostic t ool for the monitoring of small HCC.