[Experimental analysis of postoperative early recurrence of liver cancer]

The author suspected that the high incidence of early recurrence after macroscopically curative operation in human liver cancers correlated with the production of liver regeneration factor which was induced following partial hepatectomy (PH). The author therefore analyzed whether PH enhanced the growth of liver cancers or not, and the relevant mechanism involved, using rats subcutaneously injected with hepatocellular carcinoma (KDH-8, AH-66) cells. Primarily, it proved that PH significantly enhanced the growth of liver cancers injected in rats. The effect of this enhancement of liver cancer growth appeared as an abrupt increase in tumor volume within 24 hours following PH, which fact was supported by the mitotic indices of the hepatocellular carcinoma (KDH-8) cells. However PH did not affect rats injected with mammary carcinoma (SST-2) cells without estrogen receptor (E2R) or fibrosarcoma (KMT-75) cells. Secondly, based on this result, the author tried to analyze the mechanism of enhanced growth of liver cancers following PH, from the standpoints of; changes in postoperative immunity, expression of cytosol E2R in liver cancer cells or liver regeneration factor, using KDH-8 cells. The changes in postoperative immunity (NK-activity and Blastogenesis) did not correlate with the changes in liver cancer growth. Although serum estradiol (E2) increased significantly after PH, E2R was not detected in the KDH-8 cells used in this experiment. Serum was obtained from healthy rats 24 hours after PH, and 20 mg of serum, as calculated from total protein, was eluted into 50 fractions by high liquid chromatography (column; TSK G3000 SW). When the author examined which fractions stimulated both the growth of primarily cultivated hepatocytes and KDH-8 cells, only the fraction Fr. 30, the molecular weight of which was about 100 Kd, enhanced both. Furthermore, the author performed an in vivo assay to determine the number of days needed for tumor appearance: PHs were carried out 2 months, 5 days and 1 day before, at the same day of, and 1 day and 5 days after KDH-8 cell (500 cells/100 microliters, sc) inoculation. The author also noticed from these in vivo tests that PHs which were performed 1 day before, at the same day of, and 1 day and 5 days after the KDH-8 cell inoculation enhanced significantly the growth of liver cancers.