Novel method to measure serum levels of des‐gamma‐carboxy prothrombin for hepatocellular carcinoma in patients taking warfarin: A preliminary report

Des-gamma-carboxy prothrombin (DCP) is a useful tumor marker for hepatocellular carcinoma (HCC), but its utility is limited in patients taking vitamin K antagonists. We evaluated the NX-DCP ratio, a newly developed method to measure serum DCP, for its ability to identify DCP elevation induced by HCC in this patient subpopulation. Conventional DCP measurements and the NX-DCP ratio were compared in patients with and without HCC, all of whom were taking the vitamin K antagonist warfarin. We found no differences in conventional DCP measurements between patients with and without HCC due to warfarin treatment. In contrast, the NX-DCP ratio was significantly higher in patients with HCC; the NX-DCP ratio in all patients without HCC was <1.50. When the cut-off was fixed at 1.50, sensitivity and specificity for HCC diagnosis were 60.0% and 100.0%, respectively, which are comparable to those of conventional DCP measurements in patients not taking warfarin. The novel NX-DCP ratio identifies patients on warfarin with elevated DCP due to HCC and is useful as a tumor marker for HCC in this patient subpopulation.