CO2 pneumoperitoneum increases systemic but not local tumor spread after intraperitoneal murine neuroblastoma spillage in mice

Background Minimally invasive techniques are increasingly used for biopsy and resection of neuroblastoma, but the impact on the behavior of spilled tumor cells is unknown. We aimed to investigate whether CO 2 pneumoperitoneum can affect local or systemic tumor manifestation after spillage of neuroblastoma cells into the peritoneal cavity. Methods Murine neuroblastoma cells (Neuro2a, 1x10 6 ) were inoculated into the peritoneal cavity of 25 male A/J mice, which subsequently underwent CO 2 pneumoperitoneum ( n = 12) or laparotomy ( n = 13) for 1 h. At the 28th postoperative day, local (peritoneal and surface of the gut) and systemic (liver, lung, spine) tumor spread was graded in a blinded manner (1–4 point scale) and specimens were histologically examined for tumor manifestation (hematoxylin and eosin stain) and tumor cell proliferation rate (Ki-67-stain). In the case of no visible lesion, five random sections were histologically examined. Peritoneal carcinosis was graded macroscopically. Results Tumor manifestations were detected in 10 out of 12 (83%) animals after CO 2 pneumoperitoneum, and in 9 out of 13 (69%) after laparotomy (n.s.). Incidence of liver metastasis was higher after CO 2 pneumoperitoneum versus laparotomy (83% versus 31%; p