Experimental study of the effect of intra-abdominal pressure during laparoscopy on tumour growth and port site metastasis.

BACKGROUND: The influence of raised intraperitoneal pressure during laparoscopy on tumour growth and port site metastasis is still unknown.
METHODS: Tumour growth of colonic adenocarcinoma DHD/K12/TRb was measured after laparoscopy with carbon dioxide at different pressures (0, 5, 10 and 15 mmHg) in a rat model. Cell kinetics were determined after incubation with carbon dioxide (0, 5, 10 and 15 mmHg) in vitro (n=60). Additionally, tumour growth was measured subcutaneously and intraperitoneally 4 weeks after laparoscopy at different intraperitoneal pressures (5, 10 and 15 mmHg) (n=100).
RESULTS: In vitro tumour growth decreased significantly after incubation with carbon dioxide at 10 and 15 mmHg compared with a pressure of 0 or 5 mmHg. In vivo, mean(s.d.) intraperitoneal tumour weight was significantly increased after laparoscopy at 5 mmHg (919(1085) mg) and at 10 mmHg (1274(1523) mg) (P< 0.05), but decreased again after laparoscopy with an intraperitoneal pressure of 15 mmHg (731(929) mg) compared with the control group (365(353) mg) (P=0.3). Mean(s.d.) subcutaneous tumour growth was promoted after laparoscopy at 5 mmHg (172(234) mg), at 10 mmHg (190(253) mg) and at 15 mmHg (178(194) mg) compared with controls (48(33) mg) (P < 0.05).
CONCLUSION: In vitro, raised intraperitoneal pressure leads to suppression of tumour growth. In vivo, intraperitoneal tumour growth is suppressed only by higher pressure (15 mmHg). Subcutaneous tumour growth is stimulated by carbon dioxide independently of the intraperitoneal pressure.