Hepatic tumor spread of colorectal cancer in a laparoscopic animal model

Background: We devised a standardized animal model to study the impact of laparoscopic colorectal surgery on intrahepatic tumor cell growth. Methods: The technique of laparoscopic surgery in the rat was extended by endoscopic inoculation of colon cancer cells (CC531) into the portal vein (1 x 10(4), 5 x 10(4), 1 x 10(5), 3 x 10(5), 5 x 10(5) cells/ml) of WAG/Rij rats (n = 25). As controls, five animals underwent laparotomy and open intraportal inoculation of 5 x 10(4) cells/ml. Results: Hepatic tumor growth occurred after inoculation of 5 x 10(4), 1 x 10(5), 3 x 10(5), and 5 x 10(5) cells/ml. Extrahepatic tumor and conflating hepatic tumor was observed after the inoculation of 1 x 10(5), 3 x 10(5), and 5 x 105 cells/ml. Concentrations of 5 x 10(4) cells/ml injected either laparoscopically or via an open technique led to single hepatic tumor nodules. No tumor growth was seen after inoculation of 1 x 10(4) cells/ml. Conclusions: Laparoscopic intraportal tumor cell inoculation is a feasible technique to create hepatic metastases. The inoculation of 5 x 10(4) CC531 cells leads to reliable cell growth that can be used to investigate the impact of various laparoscopic techniques on tumor spread.