THE EFFECT OF PARTIAL-HEPATECTOMY ON TUMOR-GROWTH IN RATS - IN-VIVO AND IN-VITRO STUDIES

Residual tumor in the remnant liver after partial hepatectomy (PH) for colorectal liver metastases is a serious clinical problem, This fact is reflected by the high number of recurrences after potentially curat ive liver resections, Liver regeneration, it appears, might influence the growth of remaining micrometastases in the Liver. Using rats, we d emonstrated enhancement of growth of a syngeneic colon carcinoma (CC 5 31) in the remnant liver after 70% PH. Fourteen days after PH, tumor w eights in the liver were twice as high as those of sham-operated rats. This difference in tumor weight was not found in extrahepatic tumors, In vitro experiments did not show stimulation of cultured CC 531 cell s by portal or systemic serum withdrawn 24 hours or 14 days after hepa tectomy as compared with sera obtained after sham operation. Go-cultur es of CC 531 cells and hepatocytes (in ratios of 1:10 or 1:1) demonstr ated a higher H-3-thymidine incorporation than was the case in separat ely cultured cells, In co-cultures, bromodeoxyuridine (BrdU) incorpora tion in DNA was found primarily in CC 531 cells and rarely in hepatocy tes. Cell density appeared to be of influence on H-3-thymidine incorpo ration in co-cultures, Hepatocytes were found to have a stimulating ef fect on CC 531 cells in low-density cultures, whereas high density cul tures exhibited an inhibiting effect after a culture time of 120 hours , These results show that, depending on cell density in co-cultures, a paracrine stimulating influence of hepatocytes on this type of colon carcinoma cells (CC 531) might be responsible for the increased tumor growth in vivo.