A New Cell Block Method for Multiple Immunohistochemical Analysis of Circulating Tumor Cells in Patients with Liver Cancer

PURPOSE: We developed a new method of detecting circulating tumor cells (CTCs) in liver cancer patients by constructing cell blocks from peripheral blood cells, including CTCs, followed by multiple immunohistochemical analysis. MATERIALS AND METHODS: Cell blockswere constructed from the nucleated cell pellets of peripheral blood afterremoval of red blood cells. The blood cell blocks were obtained from 29 patients with liver cancer, and from healthy donor blood spikedwith seven cell lines. The cell blocks and corresponding tumor tissues were immunostained with antibodies to seven markers: cytokeratin (CK), epithelial cell adhesion molecule (EpCAM), epithelial membrane antigen (EMA), CK18, α-fetoprotein (AFP), Glypican 3, and HepPar1. RESULTS: The average recovery rate of spiked SW620 cells from blood cell blocks was 91%. CTCs were detected in 14 out of 29 patients (48.3%); 11/23 hepatocellular carcinomas (HCC), 1/2 cholangiocarcinomas (CC), 1/1 combined HCC-CC, and 1/3 metastatic cancers. CTCs from 14 patients were positive for EpCAM (57.1%), EMA (42.9%), AFP (21.4%), CK18 (14.3%), Gypican3 and CK (7.1%, each), and HepPar1 (0%). Patients with HCC expressed EpCAM, EMA, CK18, and AFP in tissue and/or CTCs, whereas CK, HepPar1, and Glypican3 were expressed only in tissue. Only EMA was significantly associated with the expressions in CTC and tissue. CTC detection was associated with higher T stage and portal vein invasion in HCC patients. CONCLUSION: This cell block method allows cytologic detection and multiple immunohistochemical analysis of CTCs. Our results show that tissue biomarkers of HCC may not be useful for the detection of CTC. EpCAM could be a candidate marker for CTCs in patients with HCC.