Usefulness of the high sensitivity PIVKA-II measurement method in diagnosis of hepatocellular carcinoma: A comparison with the conventional method

We investigated a new PIVKA-II assay kit (Eizai, ED-008) that incorporates the use of an improved secondary antibody compared with the conventional EIA method, and is highly sensitive to PIVKA-II (sensitivity: 0,0125 AU/ml). Using this new kit, we measured plasma PIVKA-II levels in 76 subjects in whom the conventional PIVKA-II assay was negative (≤ 0.0625 AU/ml). There were 30 patients with HCC, 14 patients with liver cirrhosis (six with α-fetoprotein ≥ 50 ng/ml), 11 patients with chronic active hepatitis C, 11 patients with chronic inactive hepatitis C, and ten healthy volunteers. The new assay kit detected PIVKA-II (≥ 0.0125 AU/ml) in 11 patients with HCC (36.7%), and one patient with liver cirrhosis (7.1%), but was negative in the patients with chronic active or inactive hepatitis C and the controls. Among the 11 HCC patients positive for PIVKA-II, the plasma α-fetoprotein level was greater than 100 ng/ml in two patients (18.2%), while it was above this level in three of the 19 patients negative for PIVKA-II. The mean size of the main tumor in the patients positive and negative for PIVKA-II was 2.16 + 0.87 cm and 2.62 + 1.50 cm, respectively, with no significant difference between the groups (P = 0.47). However, in seven patients positive for PIVKA-II, the tumor size was less than 2 cm. This assay also showed a high specificity for HCC (0.98). We concluded that this assay may allow PIVKA-II to be used as a more effective indicator of HCC.