DETERMINATION OF SERUM DES-GAMMA-CARBOXY PROTHROMBIN LEVELS IN PATIENTS WITH SMALL-SIZED HEPATOCELLULAR-CARCINOMA - COMPARISON OF THE CONVENTIONAL ENZYME-IMMUNOASSAY AND 2 MODIFIED METHODS

Objectives: Currently available enzyme immunoassays for des-gamma-carb oxy prothrombin (DCP) are not sensitive enough to detect hepatocellula r carcinoma (HCC) at an early stage. Therefore, the objectives of this study were to enhance the sensitivity of the currently available enzy me immunoassay (EIA) for DCP and to assess the diagnostic values of th e new methods compared with those of alpha-fetoprotein (AFP) in patien ts with small-sized HCC. Methods: Coded serum samples obtained from a total of 128 patients with chronic liver diseases, including 27 patien ts with small-sized HCC, were analyzed. DCP levels were determined in three different ways: 1) conventional EIA, 2) the overnight method, si milar to the conventional EIA but the first reaction (immunoreaction o f DCP with the monoclonal antibody) was proceeded overnight, and 3) th e avidin-biotin complex (ABC) method. Results: In 27 patients with HCC (less than or equal to 3 cm in diameter), the rates of abnormal value s obtained by the conventional, the overnight, and the ABC methods wer e 14.8, 25.9, and 29.6%, respectively. The overnight and the ABC metho ds comparably increased the sensitivity, whereas the ABC method gave t he highest false-positive value in patients with chronic liver disease s (cirrhosis and chronic hepatitis) without HCC. The negative predicti ve value was 84.9% when AFP and the overnight DCP assays were combined , whereas the true positive rate by the combination assay of the ABC m ethod for DCP and AFP (cut-off level at 200 ng/ml) was 33.3%. Conclusi ons: Two modifications of the conventional EIA for DCP comparably incr eased the sensitivity, but the overnight method may be of more practic al value in termis of specificity and ease. The rate of detection of s mall-sized HCC by tumor markers alone, however, is not satisfactory ev en when the modified DCP and AFP measurements are combined.