THURSDAYMarch 14, 2002: Basic Science Forum Abstracts BS01 BS03 EXCISION OF LAPAROSCOPIC PORT SITES INCREASES THE LIKE- RAPID FLOW CO2 LAPAROSCOPY AEROSOLISES CANCER CELLS LIHOOD OF WOUND METASTASES IN AN EXPERIMENTAL MODEL INTO PERITONEAL CAVITY BUT NOT PORT SITES IN A NEW RAT David I Watson MD FRACS, Tanya Ellis BSc (hons), Paul Leeder MODEL 1KS Zayyan FRCSE, 1JS Christie-Brown MRCPath, 1S Van MD FRCS, Susan J Neuhaus PhD, Thomas Dodd FRACP, Glyn G Noorden, 2C-Y Yiu FRCS, 1DP Sellu FRCS, 1RT Mathie PhD , 1Division Jamieson MS FACS, FRACS, The University of Adelaide Department of Surgery, Anaesthetics and Intensive Care, Imperial College School of Surgery, Royal Adelaide Hospital, Adelaide, South Australia, AUSTRALIA of Medicine, Hammersmith Hospital, London, UK, 2Whittington Background: Hospital, London, UK Case reports of patients developing tumour metastases at port Background: The role of CO2 in the pathogenesis of tumor recur- sites following laparoscopic surgery have prompted the develop- rences after laparoscopy remains controversial. This study was ment of preventive strategies to address this potential problem, designed to determine if rapid flow of CO2 contributed to the disper- including local excision of the port sites. Whilst this strategy is cur- sal of free cancer cells during laparoscopy in a new rat model. rently used clinically, its efficacy has not been established. Methods: A novel rat model of desufflation without trocar was Methods: developed and 55 Fischer rats were randomised into three groups: A 24 immune competent Dark Agouti rats underwent laparoscopy (rapid flow of CO2 at 0.67L/min, n=20), B (slow flow at 0.44L/min, and standardized intraperitoneal laceration of an implanted abdomi- n=20) and C (gasless laparoscopy, n=15). CO2 was vented via a port- nal flank tumour, using an established laparoscopic cancer model. less surgical valve that filtered cells. After suspending the abdominal Rats were randomized to either control (n=12) or wound excision wall, half of the animals in each group (non-recovery) were injected (n=12) groups. Both groups underwent laparoscopy using CO2 intraperitoneally with 7.5 x 106 immunolabelled rat colon cancer cells insufflation, and 2 mini-laparoscopy ports. In the wound excision (RCC2) while the other half (recovery), received 7.5 x 106 viable RCC2 group one of the port site wounds was excised following desuffla- prior to insufflation or gasless laparoscopy. Non-recovery animals tion of the abdominal cavity. One week later the port site wounds were killed after insufflation and parietal peritoneal and port site spec- were excised for histological examination. imens were examined for RCC2 by fluorescence microscopy (FM) and Results: flow cytometry (FC). The recovery animals were killed at four weeks Wound involvement with tumour was significantly more common for evidence of wound recurrence. following wound excision, compared with untreated controls (9 of Results: Nine of ten non-recovery animals in A had RCC2 on FM or 12 versus 2 of 12, p=0.002). In the wound excision group, tumour FC compared to two in each of non-recovery B and C (p=0.018). Two metastases arose preferentially in the excised port site wound. of these nine also had RCC2 in their portless valves. Two recovery A Conclusions: animals developed wound recurrence at 4 weeks compared to zero in This study suggests that excision of laparoscopy port site wounds following laparoscopic surgery for cancer does not prevent the sub- the other groups (p=0.315) sequent development of port site tumors. Furthermore, the excision Conclusions: Rapid flow of CO2 aerosolised free cancer cells into the of port sites may actually increase the risk of tumour metastases peritoneal cavity but not the port sites, thus supporting a role for CO2 arising in port sites, suggesting that the clinical application of this in the intraperitoneal dispersal of free tumour but not port site recur- strategy should be re-evaluated. rence. BS02 BS04 INCREASED TUMOR SPREAD AFTER CONVERSION FROM LAPARO- EFFECT OF SURGICAL TRAUMA ON EPCAM VACCINE INDUCED TUMOR SPECIFIC CELL CYTOTOXICITY AND ANTIBODY PRODUC- SCOPIC TO OPEN SURGERY Lars Brinkmann MD, Beate Richter MD, TION Irena Kirman, M.D., Ph.D., Alexandra Maydelman, Zisan Asi, Tobias Weberschock MD, Claus-Georg Schmedt MD, Carsten N Gutt B.A., Daniel Feingold, M.D., Marc Bessler, M.D., Richard L. Whelan, MD Department of General Surgery, J-W Goethe University Frankfurt, Department of Surgery, Columbia University, New York, NY Germany Surgical trauma inhibits immune function. Our goal was to study the Background: effect of surgical intervention on the development of a specific In up to 20% of tumor resection laparoscopic surgery is forced to immune response to EpCAM, a tumor associated protein. Methods: convert to conventional open technique based on diverse complicated EpCAM protein and the adjuvant MPLA were incorporated in alginate intra-abdominal conditions. Concerning the effect of conversion from beads. Control beads contained alginate only. The beads were laparoscopic to open surgery on tumor growth and spread only few implanted 3 weeks before surgery in all mice. The following experi- data are available. In terms of conversion stronger surgical manipula- mental groups (n=5) were included: anesthesia control + control beads tion and longer total operating time could have an important impact (AC-contr), anesthesia control + vaccine beads (AC-vac), open surgery on the immune function and tumor growth. + control beads (OS-contr), open surgery + vaccine beads (OS-vac), Methods: CO2 pneumopertioneum (pneumo) + control beads (CO2-contr) and 60 male WAG/Rij rats were randomised into four groups: laparoto- CO2 pneumo + vaccine beads (CO2-vac). Following surgery, mice my (Open, n = 15), laparoscopy (CO2, n = 14), early and late conver- were inoculated with EpCAM transfected C26 (C26-EpCAM) cells. Tumors were allowed to grow 5 weeks. Subsequently, blood was sion from laparoscopy to laparotomy after 30 minutes (CV 30, n = 15) obtained, mice sacrificed, their splenocytes isolated and frozen. The and after 60 minutes (CV 60, n = 15). Metastasis were induced by concentration of anti-EpCAM IgG in plasma was determined by ELISA. intrasplenic tumor cell (50,000 cells, CC531) inoculation during proce- EpCAM specific killing was assayed by flow cytometry using PI stain- dure. Total operating time was 90 minutes. Regarding CV 60 total ing and fluorescently labeled C26-EpCAM cells. Student’s t-test was operating time was 120 minutes. 28 days following surgery tumor used for statistical analysis. Results All immunized mice developed growth was evaluated regarding number, diameter and cancer index greater cytotoxic response to C26-EpCAM than their respective con- of tumor nodes. Data were analysed by Kruskal-Wallis Test. trols: AC-vac, vs AC-contr, (p<0.02), OS-vac, vs OS-contr, (p<0.01) and Results: CO2-vac, vs CO2-contr, (p<0.02). However, anti-EpCAM IgG increased After late conversion (CV 60) total tumor growth was significantly significantly in AC-vac, 3.12+/-0.78 ug/ml vs AC-contr, 0.02+/-0.04 increased compared to laparoscopy and laparotomy (p < 0.05). There ug/ml (p<0.01) and in CO2-vac, 1.22+/-0.73 ug/ml vs CO2-contr, 0.02+/- was no significant difference between Open, CO2 and CV 30. CV 30 0.04 ug/ml (p<0.01), but not in OS-vac, 0.64±1.06 ug/ml vs OS-contr, showed less tumor growth than CV 60. 0.002+/-0.64. (Tumor growth is subject of a separate abstract.) Conclusions: Conclusions Perioperatively administered encapsulated EpCAM-MPLA Conversion from laparoscopic to open surgery might result in vaccine induces specific cell mediated and antibody mediated stronger tumor growth than laparoscopic surgery (CO2) or conven- immune response in the setting of anesthesia alone or C02 pneumo. tional open surgery without conversion. From the oncological view an Although vaccination in the open surgery mice also induced a cell- mediated response, a diminished antibody response was observed early decision for conversion seems to be strongly recommended. after laparotomy. Underline denotes presenter. * denotes resident paper. http://www.8thworldcongress.org/ 77 THURSDAYMarch 14, 2002: Basic Science Forum Abstracts BS05 BS07 THE HYPOXIC PNEUMOPERITONEUM INDUCES AUGMENTED MALIGNANT POTENTIAL VIA NF-KB MEDIATED METALLOPROTEASE ALTERATIONS OF T LYMPHOCYTE SUBSETS AND TH1/TH2 BAL- UPREGULATION PF Ridgway MD, S Olsen MD, P Ziprin MD, PA ANCE FOLLOWING LAPAROSCOPY-ASSISTED DISTAL GASTRECTOM Paraskeva MD, DH Peck PhD, AW Darzi MD., Academic Surgical Unit, Kyuzo Fujii, M.D., Kazuhiro Yasuda,M.D., Masafumi Inomata,M.D., Imperial College Faculty of Medicine, St. Mary’s Hospital, London, UK Norio Shiraishi,M.D.,Yosuke Adachi,M.D., Seigo Kitano, M.D. Background: The hypoxic pneumoperitoneum causes an increased Department of Surgery I, Oita Medical University, Oita, Japan malignant potential in vitro although the antecedent mechanism is abstract: [Objective] Postoperative immunosuppression is less in unclear. The authors hypothesise that Matrix Metalloproteases (MMP), laparoscopic surgery than open surgery. There is no report about the lacking a hypoxic response element, are up regulated via a Nuclear alterations of the circulating T lymphocyte and natural killer (NK) cell Factor kappa B (NF-kB) dependant pathway. subsets following laparoscopy-assisted distal gastrectomy (LADG) and Methods: The Colonic (SW1222) tumour cell line was exposed to a conventional open distal gastrectomy (ODG) for early gastric cancer. gas displacement hypoxic model at various time points. Breast (MDA- The aim of this study was to compare the immunosuppression after MB231) cells were used to evaluate adenocarcinoma specificity. LADG to ODG. Invasion across a Matrigel coated 8um Transwell filters as well as cell [Materials and methods] Patients with early gastric cancer were viability was assessed using a MTS non-radioactive cell proliferation divided into two groups, LADG group (n=10) and ODG group (n=10) . assay (Promega). Activity of MMP 2 and 9 were assessed using gelatin Blood was taken on the preoperative day, the first, third and seventh zymography.