TROCAR SITE RECURRENCE IS UNLIKELY TO RESULT FROM AEROSOLIZATION OF TUMOR-CELLS

PURPOSE: This study was undertaken to investigate the ability of a hig h-pressure CO2 environment to aerosolize tumor cells in both in vitro and in vivo models. (An aerosol is defined as a stable gaseous suspens ion of insoluble particles.) Also, this study was designed to determin e if rapid desufflation is capable of transporting fluid laden with tu mor cells. METHODS: The four in vitro aerosol experiments were perform ed in an 18.9-1 plastic vessel fitted with two 7-mm ports and a compli ant latex balloon affixed to the top. After CO2 insufflation, the vess el was desufflated through a sterile soluset containing 25 ml of cultu re media that was subsequently emptied into a culture dish, incubated for two weeks, and periodically assessed for growth. At the bottom of the vessel, one of the following was placed: Study 1 and 2, a suspensi on of B16 melanoma or colon 26 tumor cells in Liquid culture media; St udy 3, colon 26 cells in saline solution; Study 4, several pieces of s olid colon 26 tumor. In Studies 1 to 3, cell preparations were subject ed to the following high-pressure CO2 conditions (pneumo): 1) static p neumo of 15 and 30 mmHg (10 minute dwell); 2) a continuous flow (CF) o f CO2 (10 l) while maintaining a pressure of 15 or 30 mmHg in the vess el. In Study 4, only the 30 mmHg static and CF conditions were tested. Between 6 and 12 determinations were performed for each condition and cell preparation. In vivo aerosol experiments consisted of Spraque Da wley rats that received intraperitoneal injections of 10-5 B16 cells i n 0.1 ml of liquid media. Two laparoscopic ports were placed in the ab domen, one each for insufflation and desufflation. Study groups were: 1, static CO2 pneumo of 15 mmHg; 2 and 3, continuous CO2 flow (10 l) a t a stable pneumo pressure of 5 and 10 mmHg. Desufflation was performe d via the same collecting device and handled in an identical manner to the in vitro experiments described above. The in vitro balloon experi ment was designed to investigate the ability of desufflation to transp ort fluid-containing tumor cells; latex balloon model was used. To pre vent complete loss of volume on desufflation, a wire coil was placed i nside the balloon. Twenty ml of media containing 20 X 10(-6) B16 cells was placed in the bottom of the balloon. The balloon was insufflated with 1 to 2 l of gas. There were three study groups that differed in t he degree to which the cell suspension was agitated before desufflatio n. Study conditions were as follows: 1) no agitation; 2) moderate agit ation to coat the lower walls and coil; 3) maximum agitation to coat t he entire balloon. To verify the viability of tumor cells, at the end of each in vitro and in vivo study, a sample of tumor cells or periton eal washing was incubated in sterile media. These samples served as po sitive controls. RESULTS: In vitro aerosol studies consisted of the fo llowing. At the end of two weeks of incubation, no tumor growth was no ted in any of the 124 test dishes. The 14 control samples all demonstr ated tumor growth. In vivo aerosol studies consisted of the following. Zero of 18 experimental dishes grew tumor. All three peritoneal washi ng samples demonstrated growth. In vitro balloon studies consisted of the following. Zero of 12 test dishes in Groups 1 and 2 demonstrated g rowth, whereas five of six dishes did so in Group 3 (maximally agitate d before desufflation). Again, positive controls all grew tumor cells. SUMMARY: We were unable to demonstrate aerosol formation in any of th e in vitro and in vivo studies performed. In the balloon experiment, d esufflation-related transport of tumor cells was demonstrated but only when the entire balloon surface was coated with the tumor cell suspen sion before desufflation. CONCLUSION: Aerosols of tumor cells are not likely to form. Free intraperitoneal tumor cells are most likely found in liquid suspension. Desufflation is a potential means of transport of cell-laden fluid.