Abdominal Wound Tumor Recurrence After Open and Laparoscopic-Assisted Splenectomy in a Murine Model Sang W. Lee, M.D., Richard L. Whelan, M.D., John C. Southall, M.D., Marc Bessler, M.D. From the Department of Surge(y, Columbia-Presbyterian Medical Center, New Ybrk, New York PURPOSE: The cause of abdominal wall tumor recurrences after laparoscopic surgery for cancer remains unknown. A recent study from our laboratory using a murine splenic tumor model suggests that poor surgical technique (i.e., crushing of the tumor) and not the CO 2 pneumoperito- neum is responsible for port wound tumors. However, in that experiment no actual laparoscopic procedure or ma- nipulation was performed. The purpose of the current study was to determine the rate of abdominal wound tu- mors after laparoscopic-assisted splenectomy performed via a CO 2 pneumoperitoneum vs. open splenectomy using the mouse splenic tumor model. METHODS: To establish splenic tumors, female BALB/c mice (N = 72) were given subcapsutar splenic injections of a 0.1-ml suspension con- taining 105 C-26 colon adenocarcinoma cells via a left flank incision at the initial procedure. Eight days later, animals were randomized into one of two groups: 1) laparoscopic- assisted splenectomy, or 2) open splenectomy. Laparo- scopic-assisted splenectomy animals had three laparoscopic ports placed and then underwent laparoscopic mobilization of the spleen under a CO 2 pneumoperitoneum followed by extracorporeal splenectomy via a subcostal incision. Group 2 animals underwent open splenectomy via a subcostal incision after three port incisions were made in the same locations as for laparoscopic-assisted splenectomy mice. The incision was closed after 20 minutes in both groups. Ten days later, the mice were killed and inspected for abdominal wall tumor implants. The experiment was per- formed via two separate trials. RESULTS: When results of the two trials were combined, there was no significant difference in the incidence of animals in each group with at least 1 port tumor (open, 21 percent; laparoscopic-assisted splenectomy, 33 percent; P = 0.14). However, the overall incidence of port site tumors (number of ports with tu- mors/total number of ports for each group) was signifi- cantly higher in the laparoscopic-assisted splenectomy group than in the open group (20 vs. 7 percent; P = 0.01). The subcostal incisional tumor recurrence rate was also higher in the laparoscopic-assisted splenectomy group (50 vs. 21 percent; P = 0.02). as was the perioperative mortality rate (21 vs. 7 percent; P = 0.08). Results of the two indi- vidual trials were also considered separately. The incidence of port wound tumors decreased significantly from the first to the second laparoscopic-assisted splenectomy trial Supported by the 1996 American Society of Colon and Rectal Surgeons/Ethicola Research Fellowship, Ethicon-Endosurgery Inc., Ethicon Inc. Read at the meeting of The American Society of Colon and Rectal Surgeons, Philadelphia, Pennsylvania, June 22 to 26, 1997. Address reprint request to Dr. Whelan: Atchley Pavilion, 161 Fort Washington Avenue, New York, New York 10032. 824 (36 vs. 9 percent; P = 0.003), although the incidence of tumors at the subcostal incision and the mortality rate for the two laparoscopic-assisted splenectomy group trials were not significantly different. The open group tumor incidences did not change from trim to trial. CONCLU- SIONS: Overall, significantly more port and incisional tu- mors were noted in the laparoscopic-assisted group. M- though not statistically significant, mortality rate of the laparoscopic-assisted group was higher than the open group. The reasons for these findings are unclear. Laparo- scopic mobilization was quite difficult and required exces- sive splenic manipulation, which may have liberated tumor cells from the primary tumor and facilitated port tumor formation. With increased experience, less manipulation was required to complete mobilization. Of note, the inci- dence of port tumors in the laparoscopic-assisted splenec- tomy group decreased significantly from the first to the second trims; therefore, it is possible that surgical technique is a factor in port tumor formation. However, the persis- tently high tumor incidence at the subcostal incision site argues against the hypothesis that the second trial's laparo- scopic mobilizations were less traumatic. The CO2 pneumo- peritoneum may also be a factor. Further studies are war- ranted to clarify these issues, lKey words: Port site tumor recurrence; Port wound tumors; Pneumoperitoneum; Lapa- roscopy; Splenic tumor model] Lee SW, Whelan RL, Southall JC, Bessler M. Abdominal wound tumor recurrence after open and laparoscopic-as- sisted splenectomy in a murine model. Dis Colon Rectum 1998;41:824 -831. R eports documenting the occurrence of port wound tumors following laparoscopic resection of cancers have raised legitimate concerns regarding the safety" of laparoscopic methods in this setting. The cause of these port site tumors is presently unknown. The vast majority of animal studies in this area, to date, have used cell suspension models. A number of these studies have suggested that the CO 2 pneumo- peritoneum alone may play a role in development of port wound tumor recurrences. The cell suspension model, however, has several drawbacks that make it unrealistic and, in our opinion, of limited usefulness in the study of abdominal wound recurrences. Recently, our laboratory reported the development of a mouse splenic tumor model that, in several re- spects, is a more realistic animal model for the study