To investigate the expression of P-glycoprotein (P-gp) and its correlation to chemotherapeutic efficacy in hepatocellular carcinoma (HCC) with tumor thrombi in major portal vein.

Twenty-nine patients of HCC with tumor thrombi in major portal vein following hepatectomy and thrombectomy were enrolled in this study, all the patients received immunochemotherapy postperatively. Specimens embedded in paraffin were collected for the construction of tissue microarrays. P-gp protein were visualized by immunohistochemical staining using Monoclonal antibodies JSB-1. The patients were divided into chemotherapy sensitive and resistant groups according to the staining grade. The intensity≥(++) were considered resistant to chemotherapy. Survival time was compared between the two groups and prognostic factors were identified using Cox proportional hazards model.

The positive rate of P-gp was 75.86% (22/29). Medium tumor-free survival time showed significant differences between two groups. Multivariate analysis revealed that the expression grade of P-gp was independent prognostic factor for tumor-free survival time.

In HCC with tumor thrombi in major portal vein, the overexpression of P-gp is one of the major reason for resistance to chemotherapy, detection of which will be helpful in chemotherapy decision making.