To investigate the expression of multidrug resistance- associated proteins (MRP2, MRP3) and their correlation to chemotherapeutic efficacy in hepatocellular carcinoma (HCC) with tumor thrombi in major portal vein.

Twenty-nine HCC patients with tumor thrombi in major portal vein following hepatectomy, thrombectomy and postoperative adjuvantchemotherapy were enrolled in this study. Specimens embedded in paraffin were collected for the construction of tissue microarrays. MRP2 and MRP3 were visualized by immunohistochemical staining. 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 MRP2 and MRP3 was 86.21%, 62.07% , respectively. Tumor-free survival time and overall survival time were significantly different between the two groups according to the staining grade of MRP2 (P=0.039, 0.010, respectively). Only tumor-free survival time was significantly different according to the staining grade of MRP3 (P=0.043). Multivariate analysis revealed that the expression grade of MRP2 and MRP3 was independent prognostic factor for tumor-free survival time (P=0.009, 0.002, respectively).

In HCC patients with tumor thrombi in major portal vein, the overexpression of MRP2, MRP3 is one of the major reasons for resistance to chemotherapy. Detection of MRP2 and MRP3 will be helpful in chemotherapy decision making.