Recent work using an experimental model in our laboratory has shown that the likelihood of
tumor implantation at laparoscopy port-sites following laparoscopy might be influenced by the specific gas used for insufflation. In particular
helium insufflation was associated with less port site
metastases. The model entailed an inbred rat strain and a
tumor cell
suspension of mixed heterogeneity, native to the rat strain. To determine whether our previous findings could be reproduced using a different model, we investigated the effect of insufflation with either
helium or
carbon dioxide gas on the implantation of a purified cell
suspension of cultured
cancer cells. Thirty-eight Dark Agouti rats were randomized to undergo a 40 minute period of laparoscopic insufflation with either
helium or
carbon dioxide (19 animals in each group/three different experiments). Three laparoscopy ports were placed and 2 x 10<dformgrp> <dformula> 5 </dformula> </dformgrp> cultured mammary
adenocarcinoma cells were introduced into the abdominal cavity at the beginning of the period of insufflation. The rats were killed nine days after surgery and the port sites and abdominal cavity were examined for presence of
tumor. Rats undergoing
helium insufflation were equally likely to develop port-site
metastases compared to rats undergoing
carbon dioxide insufflation. There was, however, a predilection for port site
metastases to develop at the port site used for camera placement in both groups. Because this port site accommodated a 2 mm
laparoscope, it was associated with a larger
wound than the other two port sites. Peritoneal
tumor deposits elsewhere in the peritoneal cavity were more common following
helium insufflation, compared to
carbon dioxide. The outcome of this study is different to the results from previous studies using a heterogeneous
tumor cell
suspension in the same model in our laboratory, or elsewhere, with no advantages demonstrated for insufflation with
helium gas. Purified cell
suspensions could behave differently to a heterogeneous cell
suspension of identical
cancer cells in a port-site implantation model, and other cells present within heterogeneous
tumor suspension might influence the likelihood of
metastasis. As reported previously,
tumor implantation is more likely in larger port site
wounds and this is independent of the insufflation gas.