Surgery promotes implantation of disseminated tumor cells, but does not increase growth of tumor cell clusters

Introduction: Local recurrence and peritoneal dissemination is common after intentionally curative resection of colorectal carcinoma. It is not yet clear which mechanisms stimulate post-operative intra-abdominal tumor development. Enhanced adhesion or growth of tumor cells and/or post-operative immuno suppression may influence tumor recurrence. Aims of the study: In the present study, we evaluated effects of local and remote surgery on intra-abdominal tumor development. Materials and Methods: A standardized intra-abdominal trauma was inflicted by rubbing both uterus horns in laparotomy groups, while a dorsolateral thoracotomy was performed in thoracotomy groups (on day -1, 0, or +3). To induce tumor development rats were injected intra-peritoneally with the coloncarcinoma cell line CC531s on day 0 and evaluated after 21 days. Results: Rats undergoing laparotomy and injection on day 0 showed significantly higher tumorload than control rats (195 ± 20 vs. 47 ± 29, P < 0.001). When a laparotomy was performed, the day before tumor inoculation even higher tumorload was seen (245 ± 37 vs. 195 ± 20, P < 0.01). Strikingly, performing a thoracotomy on the day before or on the same day as tumor inoculation resulted in enhanced tumorload compared to controls as well (135 ± 84 vs. 47 ± 29; P < 0.001 and 88 ± 38 vs. 47 ± 29; P < 0.02, respectively). Either laparotomy or thoracotomy 3 days after tumor cell inoculation did not affect growth of pre-existing tumor cell clusters. Conclusions: The (post) surgical intra-peritoneal microenvironment enhances successful implantation of spilled tumor cells, whereas growth of adhered tumor cell clusters is not affected. The inflammatory response as a result of remote surgery promotes successful tumor development as well.

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