Growth of hepatocellular carcinoma in the regenerating liver.

Liver resection and liver transplantation are the treatment modalities with the greatest potential for curing hepatocellular carcinoma (HCC). Tumor recurrence after resection for HCC is, however, a major problem, and an increased rate of recurrence after living donor transplantation versus cadaveric whole liver transplantation has been suggested. Factors involved in liver regeneration may stimulate the growth of occult tumors. The aim of this project was to test the hypothesis that a microscopic HCC tumor in the setting of partial hepatectomy would show enhanced growth and signs of increased invasiveness corresponding to the size of the liver resection. Hepatectomy was performed to various degrees in groups of Buffalo rats with the concomitant implantation of a fixed number of hepatoma cells in the remnant liver; a control group underwent only resection. After 21 days, the sizes and numbers of the tumors and the expression of alpha-fetoprotein (AFP), cyclin D1, calpain small subunit 1 (CAPNS1), CD34 (a microvessel density marker), vascular endothelial growth factor (VEGF), and vascular endothelial growth factor receptor 2 (VEGFR2) were evaluated and compared between the groups. The tumor volume and number increased significantly with the size of the partial hepatectomy (P < 0.05). The largest resections were also associated with increased hepatoma cell infiltration in the lungs and significant up-regulation of cyclin D1, AFP, CAPNS1, CD34, VEGF, and VEGFR2. The results suggest that liver regeneration after partial hepatectomy facilitates the growth and malignant transformation of microscopic HCC, and this could be significant for liver resection and partial liver transplantation strategies for HCC.