Nomura F, Ishijima M, Horikoshi A, Nakai T, Ohnishi K
Department of Clinical Pathology, Tsukuba University, Japan.
Am J Gastroenterol. 1996 Jul;91(7):1380-3.
Currently available enzyme immunoassays for des-gamma-carboxy prothrombin (DCP) are not sensitive enough to detect hepatocellular carcinoma (HCC) at an early stage. Therefore, the objectives of this study were to enhance the sensitivity of the currently available enzyme immunoassay (EIA) for DCP and to assess the diagnostic values of the new methods compared with those of alpha-fetoprotein (AFP) in patients with small-sized HCC.
Coded serum samples obtained from a total of 128 patients with chronic liver diseases, including 27 patients with small-sized HCC, were analyzed. DCP levels were determined in three different ways: 1) conventional EIA, 2) the overnight method, similar to the conventional EIA but the first reaction (immunoreaction of DCP with the monoclonal antibody) was proceeded overnight, and 3) the avidin-biotin complex (ABC) method.
In 27 patients with HCC ( < or = 3 cm in diameter), the rates of abnormal values obtained by the conventional, the overnight, and the ABC methods were 14.8, 25.9, and 29.6%, respectively. The overnight and the ABC methods comparably increased the sensitivity, whereas the ABC method gave the highest false-positive value in patients with chronic liver diseases (cirrhosis and chronic hepatitis) without HCC. The negative predictive 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 method for DCP and AFP (cut-off level at 200 ng/ml) was 33.3%.
Two modifications of the conventional EIA for DCP comparably increased the sensitivity, but the overnight method may be of more practical value in terms of specificity and ease. The rate of detection of small-sized HCC by tumor markers alone, however, is not satisfactory even when the modified DCP and AFP measurements are combined.
目前可用的去γ-羧基凝血酶原（DCP）酶免疫测定法对早期肝细胞癌（HCC）的检测不够敏感。因此，本研究的目的是提高目前可用的DCP酶免疫测定法（EIA）的灵敏度，并评估新方法与甲胎蛋白（AFP）相比在小肝癌患者中的诊断价值。
分析了从总共128例慢性肝病患者（包括27例小肝癌患者）获得的编码血清样本。用三种不同方法测定DCP水平：1）传统EIA；2）过夜法，类似于传统EIA，但第一个反应（DCP与单克隆抗体的免疫反应）进行过夜；3）抗生物素蛋白-生物素复合物（ABC）法。
在27例肝癌患者（直径≤3 cm）中，传统法、过夜法和ABC法获得的异常值率分别为14.8%、25.9%和29.6%。过夜法和ABC法同等程度地提高了灵敏度，而ABC法在无HCC的慢性肝病（肝硬化和慢性肝炎）患者中产生的假阳性值最高。当AFP和过夜DCP测定法联合使用时，阴性预测值为84.9%，而DCP的ABC法与AFP联合测定法（临界值设定为200 ng/ml）的真阳性率为33.3%。
对DCP传统EIA的两种改进方法同等程度地提高了灵敏度，但过夜法在特异性和简便性方面可能更具实用价值。然而，即使将改良的DCP和AFP测量方法联合使用，仅靠肿瘤标志物检测小肝癌的比率仍不令人满意。
