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Impact of laparoscopic and conventional surgery on Kupffer cells, tumor-associated CD44 expression, and intrahepatic tumor spread.

BACKGROUND
The oncologic feasibility of laparoscopic surgery for the cure of colorectal cancer is under debate. The effect of laparoscopic colorectal cancer resection on hepatic tumor spread has not yet been clarified.


HYPOTHESIS
Laparoscopic surgery affects cell-mediated immune response and hepatic tumor spread dependent on intraperitoneal insufflation.


METHODS
Thirty WAG/Rij rats were randomized into 3 operative groups: carbon dioxide (CO( 2)) laparoscopy (n = 10), "gasless" laparoscopy (n = 10), and laparotomy (n = 10). To induce liver metastases, 50 000 CC531 colon carcinoma cells were injected into the portal vein during either laparoscopy or laparotomy. Twenty-eight days after injection, specimens were explanted, sectioned, and examined immunohistochemically for CC531 tumor cells (monoclonal antibody CC52), CD44v5, v6 (monoclonal antibody OX49), and Kupffer cells (monoclonal antibody HIS36). For quantification, a morphometric analysis system was applied. Data were analyzed using the Kruskal-Wallis, Dunn, and Holm tests.


RESULTS
No statistically significant differences in hepatic tumor growth were found between CO(2) laparoscopy and laparotomy (P =.37). However, compared with CO(2) laparoscopy and laparotomy, a significant decrease in intrahepatic tumor growth was found after gasless laparoscopy (P =.02). Kupffer cells had significantly decreased after CO(2) laparoscopy and laparotomy compared with after gasless laparoscopy (P<.001 and P =.002, respectively). CD44v5, v6 expression was significantly increased after CO(2) laparoscopy and laparotomy compared with after gasless laparoscopy (P =.002 and P =.05, respectively).


CONCLUSIONS
Hepatic resistance to tumor growth is best preserved by gasless laparoscopy as opposed to CO(2) laparoscopy or laparotomy. The amount of intra-abdominal pressure with circulatory changes rather than the used gas may explain this finding. On the other hand, conventional laparoscopy vs laparotomy did not preserve hepatic immune function.