Tumor implantation following laparoscopy using different insufflation gases

Port-site metastasis and atypical recurrences after robotic-assisted radical cystectomy (RARC): an updated comprehensive and systematic review of current evidences

The objective of this systematic review is to evaluate the current evidence regarding atypical metastases in patients undergoing robotic-assisted radical cystectomy (RARC). A review of the current literature was conducted through the Medline and NCBI PubMed, Cochrane Central Register of Controlled Trials (CENTRAL) and Google Scholar databases in October 2019. From the literature search using the cited keys and after a careful evaluation of the full texts, we included 31 articles in the study. Fourteen studies (45.2%) reported at least an atypical recurrence during the follow-up period with a rate between 4 and 40% of all the recurrences. Overall, 105 (1.63%) of the 6720 patients who have been evaluated in the included studies developed an atypical recurrence. Sixty-three (60%) of these atypical metastases were peritoneal carcinomatosis, 16 (15.2%) extrapelvic lymph nodes metastases, 11 (10.5%) port-site metastases, 10 (9.5%) retroperitoneal nodal metastases, while 5 (3.8%) patients developed more than one type of atypical recurrence. In literature, there is a low but not negligible incidence of atypical recurrences after RARC. However, publication bias and retrospective design of most studies could influence the evidences. Further prospective randomized studies are needed to clarify the real risk of patients undergoing RARC to develop atypical metastases.

Evidence for the absence of visceral pain in C57BL6/N mice subjected to therapeutically relevant O3/O2-pneumoperitoneum

Each different gas that is used to induce a pneumoperitoneum (PP) exhibits individual effects within the peritoneal cavity. This might include adverse effects such as pain and/or inflammatory reactions. The acute effects of ozonized oxygen (O₃/O₂), a highly oxidative gas mixture, after being insufflated into the peritoneal cavity are analysed in this study. Using the abdominal constriction response ('writhing') assay of chemical nociception in C57BL6/N mice, O₃/O₂-PP was found not to be associated with visible pain responses and did not alter the c-fos expression in the spinal cord. In addition, mRNA expression levels of the pro-inflammatory cytokines, interleukin (IL)-1β and IL-6, were found unaltered in the spleen 2 h after insufflation. In conclusion, O₃/O₂-PP is free of adverse pain and does not trigger inflammatory immune responses.

Conditioning of the abdominal cavity reduces tumor implantation in a laparoscopic mouse model

Purpose

The addition of 4 % O₂ and 10 % N₂O to the CO₂ pneumoperitoneum (PP), together with slight cooling and humidification (conditioning), contributes to reducing adhesions by preventing mesothelial damage. We investigated the effect of peritoneal damage during laparoscopy on tumor implantation.

Methods

In Experiment 1, different tumor cell concentrations were injected into control mice without PP and into mice with 60-min dry CO₂PP (mesothelial damage). In Experiment 2, tumor cells were injected into control mice (group I) and in mice with mesothelial damage (group II). In groups III to VI, mesothelial damage was decreased by adding humidification, humidification + 10 % N₂O, humidification + 10 % N₂O + 4 % O₂, and conditioning, respectively.

Results

In Experiment 1, the tumors increased with the number of cells injected and with mesothelial damage in the abdominal cavity (p = 0.018) and abdominal wall (p < 0.0001). Experiment 2 confirmed that 60 min of dry CO₂PP increased the number of tumors in the abdominal cavity and wall (p = 0.026 and p = 0.003, respectively). The number of tumors was decreased in the abdominal cavity by conditioning (p = 0.030) and in the abdominal wall using humidified CO₂ (p = 0.032) or conditioning (p = 0.026).

Conclusions

Tumor implantation was enhanced by peritoneal damage (60 min of dry CO₂PP and desiccation), but this was prevented by conditioning. If confirmed in humans, conditioning would become important for oncologic surgery.

Tumor implantation during laparoscopy using different insufflation gases – an experimental study using cultured cancer cells

Recent work using an experimental model in our laboratory has shown that the likelihood of tumor implantation at laparoscopy port-sites following laparoscopy might be influenced by the specific gas used for insufflation. In particular helium insufflation was associated with less port site metastases. The model entailed an inbred rat strain and a tumor cell suspension of mixed heterogeneity, native to the rat strain. To determine whether our previous findings could be reproduced using a different model, we investigated the effect of insufflation with either helium or carbon dioxide gas on the implantation of a purified cell suspension of cultured cancer cells. Thirty-eight Dark Agouti rats were randomized to undergo a 40 minute period of laparoscopic insufflation with either helium or carbon dioxide (19 animals in each group/three different experiments). Three laparoscopy ports were placed and 2 x 10<dformgrp> <dformula> 5 </dformula> </dformgrp> cultured mammary adenocarcinoma cells were introduced into the abdominal cavity at the beginning of the period of insufflation. The rats were killed nine days after surgery and the port sites and abdominal cavity were examined for presence of tumor. Rats undergoing helium insufflation were equally likely to develop port-site metastases compared to rats undergoing carbon dioxide insufflation. There was, however, a predilection for port site metastases to develop at the port site used for camera placement in both groups. Because this port site accommodated a 2 mm laparoscope, it was associated with a larger wound than the other two port sites. Peritoneal tumor deposits elsewhere in the peritoneal cavity were more common following helium insufflation, compared to carbon dioxide. The outcome of this study is different to the results from previous studies using a heterogeneous tumor cell suspension in the same model in our laboratory, or elsewhere, with no advantages demonstrated for insufflation with helium gas. Purified cell suspensions could behave differently to a heterogeneous cell suspension of identical cancer cells in a port-site implantation model, and other cells present within heterogeneous tumor suspension might influence the likelihood of metastasis. As reported previously, tumor implantation is more likely in larger port site wounds and this is independent of the insufflation gas.

Drugs of anaesthesia and cancer

Anaesthesia represents one of the most important medical advances in history, and, nowadays, can widely be considered safe, thanks to the discovery of new drugs and the adoption of modern technologies. Nevertheless, anaesthetic practices still represent cause for concern regarding the consequences they produce. Various anaesthetics are frequently used without knowing their effects on specific diseases: despite having been reported that invasion or metastasis of cancer cells easily occurs during surgical procedures, numerous anaesthetics are used for cancer resection even if their effect on the behaviour of cancer cells is unclear. Guidelines for a proper use of anaesthetics in cancer surgery are not available, therefore, the aim of the present review is to survey available up-to-date information on the effects of the most used drugs in anaesthesia (volatile and intravenous anaesthetics, nitrous oxide, opioids, local anaesthetics and neuromuscular blocking drugs) in correlation to cancer. This kind of knowledge could be a basic valuable support to improve anaesthesia performance and patient safety.

The addition of 4% oxygen to the CO(2) pneumoperitoneum does not decrease dramatically port site metastases

STUDY OBJECTIVE

Port site metastases (PSM) after laparoscopic surgery for advanced-stage ovarian carcinoma are a cause of concern, but the pathophysiology is unknown. Because CO(2) pneumoperitoneum was recently demonstrated to be a cofactor in adhesion formation and tumor implantation in a laparoscopic mouse model, and because both could be prevented by the addition of 4% oxygen to the CO(2) pneumoperitoneum, we wanted to test the hypothesis that PSM could be related to tumor cell hypoxia during CO(2) pneumoperitoneum.

DESIGN

A randomized controlled pilot trial to compare the incidence of PSM in women undergoing laparoscopy with a pure CO(2) pneumoperitoneum in comparison with women with CO(2) pneumoperitoneum with the addition of 4% oxygen (Canadian Task Force classification C).

SETTING

University Hospital Gasthuisberg, Leuven, Belgium.

PATIENTS

Since January 1, 2007, 22 consecutive women undergoing laparoscopy for suspected ovarian cancer with subsequent debulking laparotomy were included.

INTERVENTIONS

Diagnostic laparoscopy with 100% CO(2) versus laparoscopy with addition of 4% oxygen.

MEASUREMENTS AND MAIN RESULTS

In the control group, 9 (47%) PSM found in 19 port sites were excised. In the CO(2)+oxygen group, a similar incidence was found, that is, 8 (50%) PSM in 16 port sites. The incidence of PSM was higher in small women (p <.018) and in high-grade malignancies. The pathophysiology of PSM is unknown, but besides direct wound contamination, aerosolization of tumor cells and gas leaks have been suggested together with a causal relationship with the CO(2) pneumoperitoneum. Tumor cell hypoxia probably is not an important mechanism because PSM were not prevented by adding small amounts of oxygen to the CO(2) pneumoperitoneum.

CONCLUSION

The hypothesis of tumor cell hypoxia by the CO(2) pneumoperitoneum as a mechanism for PSM could not be confirmed.

The uses of helium and xenon in current clinical practice

The noble gases have always been an enigma. Discovered late in the history of chemistry and in seemingly small quantities in our atmosphere, they are some of the most unreactive elements known. However, despite being extremely inert, the noble gases (helium, neon, argon, krypton, xenon and radon) have found diverse and ever expanding applications in medicine. Of all of them, the gases that have found the greatest number of uses in the field of anaesthesia and related specialties are helium and xenon. This review focuses on the history of the discovery of both gases, their unique physicochemical properties and describes their uses in clinical practice with particular emphasis on those applicable to anaesthesia.

Laparoscopic resection of curable colon and rectal cancer: an evidence-based review

The initial enthusiastic application of laparoscopic techniques to colorectal surgical procedures was tempered in the early 1990s by reports of tumor implants in the laparoscopic incisions. Substantial evidence has accumulated, including evidence from randomized controlled trials, to support that laparoscopic resection results in oncologic outcomes similar to open resection, when performed by well-trained, experienced surgeons. This review was developed in conjunction with guidelines published by the Society of American Gastrointestinal and Endoscopic Surgeons. Data from the surgical literature concerning laparoscopic resection of curable colorectal cancer was evaluated regarding diagnostic evaluation, preoperative preparation, operative techniques, prevention of tumor implants, and training and experience. Recommendations are accompanied by an assessment of the level of supporting evidence available at the time of the development of the guidelines.

Is carbon dioxide insufflation safe for laparoscopic surgery? A model to assess the effects of carbon dioxide on transitional-cell carcinoma growth, apoptosis, and necrosis

PURPOSE

To study the effects of carbon dioxide insufflation pressure and concentration on the adhesion, growth, apoptosis, and necrosis of transitional-cell carcinoma (TCC).

MATERIALS AND METHODS

Adhesion and growth of the AY-27 rat TCC cell line was measured after CO2 insufflation in vitro at different pressures ranging from 0 to 15 mm Hg and after incubation in CO2-air mixtures at 5%, 10%, and 15% CO2 by volume.

RESULTS

Tumor adhesion decreased significantly after CO2 insufflation. For all insufflation pressures, there was an increase in cell growth, apoptosis, and necrosis for the first 24 hours followed by a steady decline. High concentrations of CO2 (>5%) inhibited cell growth for only the first 48 hours. The effects of CO2 pneumoperitoneum on tumor-cell adhesion, growth inhibition, apoptosis, and necrosis were more prominent at high CO2 pressure (> or =15 mm Hg) and concentration (>5% CO2). However, insufflation pressure had a greater inhibitory effect on tumor growth than did CO2 concentration. High insufflation pressures and CO2 concentrations significantly decreased extracellular pH.

CONCLUSION

The short-term effect of CO2 on TCC growth and apoptosis is complex. Overall, CO2 has a toxic effect on TCC and inhibits cell adhesion and growth. High CO2 concentrations (>5%) and high insufflation pressures (> or =15 mm Hg) are most effective in decreasing tumor-cell adhesion and growth.

Diagnostic laparoscopy and ultrasonography for colorectal liver metastases

BACKGROUND AND AIMS

To evaluate diagnostic laparoscopy (DL) and laparoscopic ultrasonography (LUS) in the diagnostic workout of patients with colorectal liver metastases, who were considered to have resectable disease after multi detector computed tomography (MDCT).

MATERIAL AND METHODS

The medical records of 45 patients, 22M/23F, mean age 62.0 (+/-10.6), who were considered to have resectable liver metastases after CT-scan, were analysed.

RESULTS

DL and LUS could not be performed in 7 patients (16%) because of adhesions. Unresectable disease was detected by DL in 3 patients (7%), in all cases due to carcinosis. Additional lesions in the liver were detected by DL in 2 cases (4%), none of these making the patient unresectable. LUS showed additional lesions in 3 patients (7%), which in one case (2%) made the patient unresectable. None of the patients in the present study experienced adverse effects to DL or LUS.

CONCLUSION

DL and LUS, due to the low efficacy with regard to avoid unnecessary laparotomies and the relative high failure rate because of adhesions, should not be a routine part of the diagnostic work out in patients with colo-rectal liver metastases.

Minimally invasive management of colon cancer

One of the most controversial issues in minimally invasive surgery has been the implementation of laparoscopic techniques for the curative resection of colorectal malignancies. Initial concerns included the potential violation of oncologic principles, the effects of carbon dioxide, and the phenomenon of port site tumor recurrence. Basic science research and large randomized controlled trials are now demonstrating that these fears were unjustified. Long-term outcomes of laparoscopic colon resection compared with open colon resection for malignancy are comparable, and there may even be a survival benefit for a subset of patients who undergo laparoscopic resection.

Effect of acidosis on expression of mesothelial cell plasminogen activator inhibitor type-1

BACKGROUND

Abdominal mesothelial cells are exposed to carbon dioxide during laparoscopy. Previous data indicate that carbon dioxide increases release and expression of plasminogen activator inhibitor type-1 (PAI-1) and induces acidification.

METHODS

To assess the impact resulting from a range of pH, human mesothelial cells were exposed to culturing media balanced to pH levels of 6.0 to 8.0 for 90 min. Samples from cell media were withdrawn at several time points. Concentrations of PAI-1 and PAI-1 activity were measured using enzyme-linked immunoassay techniques. To focus on the effect of clinically relevant pH, cells were subjected to pH 6.4 and 7.4. Samples were withdrawn for PAI-1 assessments and for PAI-1 mRNA analyses.

RESULTS

During exposure to various levels of pH, PAI-1 secretion and activity were variable. However, 5 h after exposure, greater concentration and activity of PAI-1 were observed in acidified cultures. More PAI-1 mRNA was isolated after exposure of cells to a pH of 6.4, apparently indicating transcriptional regulation.

CONCLUSIONS

Mesothelial cells seem to respond to acidification by an increased release and production of PAI-1 in vitro.

Does CO2 pneumoperitoneum alter the ultra-structuture of the mesothelium?

BACKGROUND

Pneumoperitoneum may be responsible for ultra-structural alterations in the mesothelium during laparoscopy. To characterize the effect of pneumoperitoneum on the mesothelial cells with CO(2) and compressed air; and to compare to laparotomy and control group (anesthesia only).

MATERIALS AND METHODS

Forty C-57 mice were divided in four groups of 10 animals each: CO(2), air, laparotomy, and control group. The animals were submitted to pneumoperitoneum at 8 mmHg during 30 min (CO(2) or compressed air). Five animals of each group were sacrificed 2 and 24 h after the procedure. Fragments of parietal peritoneum were collected and processed for scanning electron microscopy.

RESULTS

Control group revealed uninterrupted mesothelial cells, without any evidence of cellular limits; close contact between the cells; absence of intercellular clefts and presence of microvilli. In the laparotomy group, similar results to the control group, with decreased microvilli were noted. Air pneumoperitoneum was associated with alterations in the morphology of the mesothelial cells, clear cellular limits, and cells with spherical and fusiforme formats. CO(2) pneumoperitoneum showed mesothelial cells with clear cellular limits, predominantly spherical cellular format, and intercellular clefts that allowed the visualization of the exposed basal membrane. These alterations were more intense after 24 h. There was a statistical significance between CO(2) group (2 and 24 h) compared to the control group and laparotomy for cellular limits, intercellular clefts and microvilli, P < 0.0001.

CONCLUSIONS

Pneumoperitoneum causes damage in the mesothelial ultra-structure, which differs from the laparotomy group. CO(2) pneumoperitoneum is more harmful to the mesothelium than the air.

Laparoscopic port-site metastases in patients with gynecological malignancies

OBJECTIVE

The purpose of this study is to review all reported cases of laparoscopic port-site metastases in patients with gynecological malignancies. Potential etiologies as well as options for prevention are discussed.

METHODS

We searched the Medline database for English-language articles presenting raw data on laparoscopic port-site metastases in patients with gynecological malignancies.

RESULTS

We found 31 articles describing port-site metastases in 58 patients. Forty patients had low malignant potential (seven patients) or invasive ovarian carcinoma (33 patients). The median age of these patients was 50 years (range: 22-79), and 83% had advanced (stage III or IV) disease. Seventy-one percent of the patients (24 of 34) had ascites, and 97% (29 of 30) had carcinomatosis. Seventy-five percent of the laparoscopic procedures in this group were performed for diagnosis. Median time to diagnosis of port-site metastases was 17 days (range: 4-730). Seventy-one percent of port-site recurrences (15 of 21) were isolated to a tissue-manipulating port. Twelve patients had port-site metastases after laparoscopy for cervical cancer. The median age was 44 years (range: 31-74). Eighty percent of cases were squamous cell carcinoma. In 75% of the patients, laparoscopy was performed for therapeutic purposes. The median time to diagnosis of port-site metastases was 5 months (range: 1.5-19). Four patients had port-site metastases after laparoscopy for uterine cancer. The median age was 63 years (range: 56-72). The median time to diagnosis of metastases was 13.5 months (range: 6-21). Half of the recurrences were in the tissue-manipulating port. Port-site metastases after laparoscopy were reported for one patient each with a diagnosis of fallopian tube carcinoma and vaginal carcinoma.

CONCLUSIONS

Laparoscopic port-site metastases are a potential complication of laparoscopy in patients with gynecological malignancies, even in patients with early-stage disease.

Laparoscopy and Malignancy

BACKGROUND

The advantages of pneumoperitoneum-based surgery are well documented. Laparoscopy is the gold standard of treatment in certain benign conditions such as cholelithiasis and gastroesophageal disease. This success has led to the application of laparoscopy in the management algorithm of malignant conditions. There is currently no universally accepted consensus of the role of pneumoperitoneum-based surgery in the treatment of cancer. This is due to the early reports of port site metastasis, initial lack of randomized controlled trials and the concern of performing oncologically adequate operations. The aim of this section is to review the current literature and attempt to obtain a consensus of the role of laparoscopy in the treatment of cancer.

MATERIALS AND METHODS

A literature search was conducted through Pubmed with key words laparoscopy, pneumoperitoneum, carbon dioxide, malignancy, cancer, and port site metastasis. The obtained results were divided into various sections such as non-randomized reports, randomized reports, animal studies, human studies, etc. A comparison was made between laparoscopic and open resections when possible.

RESULTS

There are several published reports of studies in animal models and in humans relating to pneumoperitoneum-based surgery in the setting of malignancy. There are also a few randomized controlled trials that compared open versus laparoscopic surgery for malignancies of various organ systems. In addition, the early reports of alarmingly high rate of port site metastasis have been scaled down to rates comparable to wound recurrences after open resections.

SUMMARY

Laparoscopy has added another dimension to the management of patients with cancer. Advanced training, superior instrumentation, and a better understanding of the pathophysiology of carbon dioxide pneumoperitoneum has led to the successful application of laparoscopy. The improved results are obtained in centers with high volume of patients and with experience in both fields of oncology and minimally invasive surgery. Laparoscopy is now an integral tool in the management algorithm of malignancies of some organ systems and its role will be further expanded in the future.

Effect of carbon dioxide pneumoperitoneum and wound closure technique on port site tumor implantation in a rat model

BACKGROUND

The purpose of this study was to evaluate the effects of carbon dioxide (CO2) pneumoperitoneum and wound closure technique on port site tumor implantation.

METHODS

A standard quantity of rat mammary adenocarcinoma (SMT2A)was allowed to grow in a flank incision in Wistar-Furth rats (n = 90) for 14 days. Thereafter, 1-cm incisions were made in each animal in three quadrants. There were six control animals. The experimental animals were divided into a 60-min CO2 pneumoperitoneum group (n = 42) and a no pneumoperitoneum (n = 42) group. The flank tumor was lacerated transabdominally in the experimental groups. The three wound sites were randomized to closure of (a) skin; (b) skin and fascia; and (c) skin, fascia, and peritoneum. The abdominal wounds were harvested en bloc on postoperative day 7.

RESULTS

Histologic comparison of the port sites in the pneumoperitoneum and no-pneumoperitoneum groups did not demonstrate a statistically significant difference in tumor implantation for any of the closure methods. Evaluation of the closure techniques showed no statistical difference between the pneumoperitoneum group and the no-pneumoperitoneum group in the incidence of port site tumor implantation. Within the no-pneumoperitoneum group, there was a significant increase (p = 0.03) in tumor implantation with skin closure alone vs all three layers. Additionally, when we compared all groups by closure technique, the rate of tumor implantation was found to be significantly higher (p = 0.01) for skin closure alone vs closure of all three layers.

CONCLUSIONS

This study suggests that closure technique may influence the rate of port site tumor implantation. The use of a CO2 pneumoperitoneum did not alter the incidence of port site tumor implantation at 7 days postoperatively.

Increased tumor growth after high pressure pneumoperitoneum with helium and air

BACKGROUND

Tumor growth appears proportional to the pressure of carbon dioxide insufflation during laparoscopic surgery. Air and helium are alternative insufflation gases. The objective of this study is to assess tumor growth after air and helium insufflation at different pressures.

METHOD

Ninety-six WAG rats were allocated to either air or helium. In both arms, rats were randomly exposed to a one hour gasless procedure, or to 4 mm Hg, 10 mm Hg, or 16 mm Hg insufflation. At the start of the procedure, 500,000 CC531 tumor cells were injected intraperitoneally. After three weeks, intraperitoneal tumor growth was assessed.

RESULTS

Higher insufflation pressures were associated with greater tumor growth. No difference of tumor growth between air and helium insufflation was found.

CONCLUSION

In this experimental model, insufflation pressure appeared to have a greater impact on tumor growth than the type of gas. Further studies are necessary but it seems prudent to recommend employment of lower insufflation pressures in laparoscopic oncologic surgery.

Power spectral analysis of heart rate variability during helium pneumoperitoneum: The mechanism of increased cardiac sympathetic activity and its clinical significance

BACKGROUND

Carbon dioxide pneumoperitoneum (PP) is known to induce increased cardiac sympathetic expression. The role of the insufflated gas involved in this mechanism should be elucidated in an attempt to eliminate its possible serious consequences.

METHODS

Twenty-five patients undergoing elective laparoscopic cholecystectomy were prospectively analyzed for cardiac autonomic nervous activity by spectral heart rate variability. In 15 patients, helium was used as CO(2) substitution for abdominal insufflation (study group). Four frequency bands of interest were obtained from the power spectrum of R-R intervals, as well as the ratio between the low and high frequency (LF/HF), using the fast Fourier transformation algorithm to characterize the synergy of both autonomic branches during PP.

RESULTS

Significantly increased values of the power spectrum related to the LF and VLF bands (from 130 to 377 msec(2)/Hz and from 145 to 516 msec(2)/Hz, respectively) were inspected during CO(2) PP, as well as increased LF/LH ratio (2.1). Using helium as CO(2) substitution has eliminated the significant changes in the power spectrum that reflect increased cardiac sympathetic activity.

CONCLUSIONS

The elimination of sympathetic predominance by helium PP indicates the central role of CO(2) in establishing this phenomena. Considering this information and its other known advantages, helium should be considered for use during prolonged laparoscopic procedures for high-risk patients.

Carbon dioxide pneumoperitoneum causes severe peritoneal acidosis, unaltered by heating, humidification, or bicarbonate in a porcine model

BACKGROUND

Carbon dioxide (CO(2)) is the most common gas used for insufflation in laparoscopy, but its effects on peritoneal physiology are poorly understood. This study looks at the changes in peritoneal and bowel serosal pH during CO(2) pneumoperitoneum, and whether heating and humidification with or without bicarbonate alters the outcomes.

METHODS

Twenty-one pigs divided into four groups as follows: (1) standard (STD) laparoscopy (n = 5); (2) heated and humidified (HH) laparoscopy (n = 6); (3) heated and humidified with bicarbonate (HHBI) laparoscopy (n = 5); and (4) laparotomy (n = 5). Peritoneal pH, bowel serosal pH, and arterial blood gas (ABG) were obtained at 15-min intervals for 3 h.

RESULTS

Severe peritoneal acidosis (pH range 6.59-6.74) was observed in all laparoscopy groups, and this was unaltered by heating and humidification or the addition of bicarbonate. Bowel serosal acidosis was observed in all laparoscopy groups with onset of pneumoperitoneum, but it recovered after 45 minutes. No significant changes in peritoneal or bowel serosal pH were observed in the laparotomy group.

CONCLUSION

CO(2) pneumoperitoneum resulted in severe peritoneal acidosis that was unaltered by heating and humidification with or without bicarbonate. Alteration in peritoneal pH may conceivably be responsible for providing an environment favorable for tumor-cell implantation during laparoscopy.

Laparoscopic resection of colon Cancer: Consensus of the European Association of Endoscopic Surgery (EAES)

BACKGROUND

The European Association of Endoscopic Surgery (EAES) initiated a consensus development conference on the laparoscopic resection of colon cancer during the annual congress in Lisbon, Portugal, in June 2002.

METHODS

A systematic review of the current literature was combined with the opinions, of experts in the field of colon cancer surgery to formulate evidence-based statements and recommendations on the laparoscopic resection of colon cancer.

RESULTS

Advanced age, obesity, and previous abdominal operations are not considered absolute contraindications for laparoscopic colon cancer surgery. The most common cause for conversion is the presence of bulky or invasive tumors. Laparoscopic operation takes longer to perform than the open counterpart, but the outcome is similar in terms of specimen size and pathological examination. Immediate postoperative morbidity and mortality are comparable for laparoscopic and open colonic cancer surgery. The laparoscopically operated patients had less postoperative pain, better-preserved pulmonary function, earlier restoration of gastrointestinal function, and an earlier discharge from the hospital. The postoperative stress response is lower after laparoscopic colectomy. The incidence of port site metastases is <1%. Survival after laparoscopic resection of colon cancer appears to be at least equal to survival after open resection. The costs of laparoscopic surgery for colon cancer are higher than those for open surgery.

CONCLUSION

Laparoscopic resection of colon cancer is a safe and feasible procedure that improves short-term outcome. Results regarding the long-term survival of patients enrolled in large multicenter trials will determine its role in general surgery.

Port site metastases

BACKGROUND

Concerns about port site metastases have limited the application of minimally invasive surgery for intra-abdominal malignancies. The purpose of this review article was to summarize the current literature regarding port site metastases.

METHODS

A Medline search identified >100 articles in English published during the last 15 years regarding the history, incidence, etiology, and prevention of port site metastases. These articles were reviewed and are summarized.

RESULTS

The incidence of port site metastases, initially thought to be as high as 21%, is now thought to be closer to the incidence of wound metastases after open surgery. Multiple etiologic factors have been studied including direct wound contamination, surgical technique, effects of carbon dioxide pneumoperitoneum, and changes in host immune response. Various preventive measures have been proposed.

CONCLUSIONS

Port site metastases are a well-documented and devastating complication after laparoscopic resection of intra-abdominal malignancies. Although the etiology is not yet understood, a number of factors are contributory. All efforts should be made to prevent port site metastases.

Laparoscopic colon resection for colon cancer

INTRODUCTION

Laparoscopic colon resection for cancer is as yet an unproven operation. This review article summarizes current data on the topic.

METHODS

A Medline review identified articles published since 1990 summarizing patients with potentially curable colon cancer who underwent a laparoscopic-assisted colon resection. Only articles that were randomized or had a control group with historical or matched open cases were used.

RESULTS

Very few prospective randomized controls exist. Several clinical trials are under way with one completed. Data thus far support some patient benefits with a laparoscopic approach. No differences in morbidity, oncologic data, or survival appear to exist.

CONCLUSIONS

The results of ongoing clinical trials are still needed to further evaluate the role of laparoscopic assisted colon resection in patients with potentially curable colon cancer.

Laparoscopic port-site metastases: etiology and prevention

OBJECTIVE

The purpose of this article is to summarize current hypotheses for the possible sources of laparoscopic port-site metastasis, to review the results of experimental models that support such hypotheses, and to discuss the potential options for preventing these metastases.

METHODS

We performed a Medline search to identify in vitro and in vivo studies and clinical trials that analyzed port-site metastases associated with laparoscopic surgery. We report the incidence of port-site metastases and causative factors associated with this condition.

RESULTS

The estimated incidence of port-site metastases in all patients undergoing laparoscopic surgery for malignant disease is approximately 1-2%. Multiple factors are associated with this complication. Among the most common proposed etiologies are the wound implantations caused by the surgical technique and instrumentation; the leakage of insufflation gas through the ports, known as the "chimney effect"; and the impact of pneumoperitoneum on local immune reactions. Several preventive measures, have been suggested, including careful patient selection, lavage of the peritoneal cavity as well as of the port wounds with cytotoxic agents, and modifications of surgical technique.

CONCLUSIONS

Only through the results of well-conducted large multi-institutional prospective randomized trials will we learn not only the true incidence of port-site metastases, but also the potential factors that lead to the occurrence of this complication.

Laparoscopic resection of colonic cancer

Laparoscopic resection of colonic cancer can be regarded as a safe and efficacious procedure. Short-term outcome is better after laparoscopic colectomy than after open colectomy. Long-term results of the first published randomized clinical trial indicate improved cancer related survival following laparoscopic resection of colonic cancer. However, patients included in this single center study were operated on by highly experienced laparoscopic surgeons and included relative small numbers of patients. Results of other large randomized controlled trials have to be awaited before laparoscopic resection can be recommended for colonic cancer. Higher in-hospital costs and a long learning curve hinder rapid implementation of laparoscopic colectomy into general surgical practice. Integration of laparoscopic surgery into surgical training programs is mandatory.

Minimally invasive exploration of the female reproductive tract in infertility

Classically, invasive and non-invasive tests are performed to evaluate the causes of infertility. Transvaginal hydrolaparoscopy (THL) allows the exploration of the pelvic structures with a mini-endoscope, using a vaginal needle-guided trocar introduction technique and saline as a distension medium. A first study on 349 patients demonstrated the feasibility of the procedure and gave a high patient satisfaction. Access to the pouch of Douglas was achieved in 330 patients (94.5%) under local anaesthesia and in an ambulatory environment. The mean pain score measured on a visual analogue scale of 10 was 2.7, comparable to the score of mini-hysteroscopy only and significantly lower than the scores of hysterosalpingography with either metal cannula or balloon catheter. A total of 96% of the patients agreed to repeat the procedure under the same circumstances if required. The diagnostic accuracy of the technique was demonstrated in a prospective study, in which two independent endoscopists explored 10 patients with both THL and standard laparoscopy. The inter-observer agreement for ovarian adhesions was 75% for standard laparoscopy and 90% for THL. In addition, in patients with mild endometriosis, more peri-ovarian adhesions were detected with THL than with standard laparoscopy. A multinational survey to evaluate the risk and outcome of bowel injury during THL registered 24 (0.65%) cases in 3667 procedures. In all cases, the diagnosis was made immediately and the treatment was conservative without complications.

Helium vs carbon dioxide gas insufflation with or without saline lavage during laparoscopy

BACKGROUND

Helium is an inert gas that, if used for insufflation during laparoscopy, may be followed by less postoperative pain than carbon dioxide (CO2) insufflation, due to a more limited effect on intraabdominal pH and metabolism. Saline lavage has also recently been shown to reduce postoperative pain following laparoscopic surgery. To evaluate these possibilities and to better define the clinical safety of helium insufflation, we undertook a prospective randomized trial comparing CO2 and helium insufflation with or without saline lavage in patients undergoing elective laparoscopic upper abdominal surgery.

METHODS

From January to November 2000, 173 patients undergoing elective laparoscopic cholecystectomy or fundoplication were randomized to undergo laparoscopy with either CO2 or helium insufflation. Within each group, patients were further randomized to undergo peritoneal lavage with 2 L of 0.9% saline at the end of the surgical procedure. This yielded the following four patient groups; CO2 (group 1, n = 47), CO2 + saline lavage (group 2, n = 43), helium (group 3, n = 43) and helium + saline lavage (group 4, n = 40). Patients were blinded to their randomization, and post-operative assessment was also performed by a blinded investigator, who applied a standardized scoring system to assess postoperative pain.

RESULTS

The study groups were well matched for age, sex, weight, American Society of Anesthesiologists (ASA) status, duration of surgery, and volume of gas utilized, and 81% of patients were discharged within 48 h. There were no differences in the incidence of postoperative complications among the study groups, and postoperative pain scores were not significantly different when all four groups were compared. When helium (groups 3 and 4) was compared with CO2 (groups 1 and 2), no differences in pain score were seen. When no lavage (groups 1 and 3) was compared with lavage (groups 2 and 4), less pain was found in the group undergoing saline peritoneal lavage (mean 4-h pain score, 5.9 vs 5.2; 24-h pain score, 4.8 vs 4.1; p > 0.05).

CONCLUSIONS

The use of helium insufflation for laparoscopic surgery, while not associated with any significant adverse sequelae, was not associated with less postoperative pain in this trial. The use of saline peritoneal lavage was associated with less pain in the early postoperative period.

Tumour implantation following laparoscopy using different insufflation gases

BACKGROUND

Because of the possibility of intraperitoneal seeding and port-site recurrences following laparoscopic surgery, the role of laparoscopy in cancer surgery remains controversial. Previous experimental studies have suggested that chemical, metabolic and immunological changes following carbon dioxide (CO2) insufflation may be responsible for this phenomenon. Earlier experimental studies done by the University of Adelaide Department of Surgery have also shown that helium insufflation is associated with none of the adverse changes brought about by CO2 insufflation. Helium insufflation is also associated with lower rates of intra-abdominal tumour spread. The aim of this study was to determine whether these identified benefits apply to inert gases in general.

METHODS

Twenty-four Dark Agouti rats were randomized to undergo laparoscopy with 40 min insufflation using one of the following four gases (six rats in each group); CO2, helium, argon and nitrogen. A tumour cell suspension was injected into the abdominal cavity at the beginning of laparoscopy. The rats were killed 7 days after surgery, and the peritoneal cavity and port sites were examined for the presence of tumour.

RESULTS

Rats undergoing helium insufflation, had the least number of port-site recurrences and the least amount of intraperitoneal tumour spread. Argon and nitrogen pneumoperitoneum were associated with a large number of port-site recurrences and widespread tumour seeding. The effect of CO2 insufflation was intermediate.

CONCLUSION

The choice of insufflation gas influences the incidence of port-site metastases and the degree of intraperitoneal tumour spread following laparoscopic cancer surgery. The reduced port-site recurrences and intraperitoneal spread that followed helium pneumoperitoneum is likely to be a unique property of this gas rather than a property of inert gases in general.

Morphology of the murine peritoneum after pneumoperitoneum vs laparotomy

BACKGROUND

Although there have been studies of the effects of pneumoperitoneum on the peritoneal cavity, we still do not know whether the morphologic changes to the peritoneum are different for pneumoperitoneum vs laparotomy. Using scanning electron microscopy, we examined the murine peritoneum after pneumoperitoneum vs laparotomy and compared the changes.

METHODS

Forty-five mice were anesthetized with diethyl ether and divided into seven groups. Pneumoperitoneum was established at 5 mmHg for 30 min with carbon dioxide (CO(2)) (n = 9), helium (n = 9), and air (n = 9). One group underwent laparotomy for 30 min (n = 9), and a control group underwent anesthesia only (n = 3). CO(2) pneumoperitoneum was further established at 10 mmHg for 30 min (n = 3) and at 5 mmHg for 60 min (n = 3). After the procedures, the peritoneum was resected from the mesenterium of the small intestine in each animal and examined by scanning electron microscope for morphologic changes of the mesothelial cells.

RESULTS

Bulging up of the mesothelial cells was evident immediately after pneumoperitoneum, whereas detachment of the mesothelial cells was present immediately after laparotomy. Bulging up of the mesothelial cells was reduced at 24 h after CO(2) pneumoperitoneum and fully resolved at 72 h in all pneumoperitoneum groups, whereas the mesothelial cells remained detached at 72 h in the laparotomy group. Intercellular clefts were found immediately after helium pneumoperitoneum and were present at 24 h and 72 h after helium pneumoperitoneum, but they were not seen after air pneumoperitoneum and were only evident after CO(2) pneumoperitoneum at 10 mmHg. Depression of the mesothelial cell surface was observed when pneumoperitoneum lasted 60 min.

CONCLUSION

Morphologic peritoneal alterations after pneumoperitoneum differed from those after laparotomy and were influenced by the type of gas, amount of pressure, and duration of insufflation. These peritoneal changes after pneumoperitoneum may be associated with a specific intraperitoneal tumor spread after laparoscopic cancer surgery.

A proteinase inhibitor decreases tumor growth in a laparoscopic rat model

BACKGROUND

The balance between proteolysis and protease inhibition in the formation and breakdown processes of the extracellular matrix plays a major role in tumor cell invasion. An understanding of this relationship gave rise to the therapeutic concept of lowering tumor cell invasion by inhibiting protease activity. Phosphoramidon is an unspecific proteinase inhibitor. This experimental study investigated the effect of intraperitoneal phosphoramidon administration on tumor growth in a laparoscopic rat model.

METHODS

In the first phase of the study, we investigated the influence of phosphoramidon on tumor cell invasion in a collagen matrix gel chamber in vitro. In a second experiment, a suspension of colon carcinoma cells (CC531) was introduced into the peritoneal cavity of male WAG rats. Prior to laparoscopy (at 6 mmHg for 20 min), the animals were randomized to two groups. At the start of laparoscopy, the test substance was applied intraperitoneally (group 1: controls, 1 ml 0.9% NaCl; group 2: 250 mg phosphoramidon in 1 ml 0.9% NaCl). Three weeks after the injection of tumor cells, the animals were autopsied and the tumor mass determined.

RESULTS

In comparison with the control group (tumor weight 7.42 +/- 1.01 g), intraperitoneal tumor growth in the experimental group was significantly (p < 0.001) reduced by the application of phosphoramidon (tumor weight, 3.22 +/- 1.06 g). Phosphoramidon also significantly (p < 0.05) reduced tumor cell invasion through the matrix gel.

CONCLUSION

The proteinase inhibitor phosphoramidon reduced tumor cell invasion in vitro and tumor cell growth in vivo in this laparoscopic rat model.

Metabolic and immunologic consequences of laparoscopy with helium or carbon dioxide insufflation: a randomized clinical study

BACKGROUND

Previous studies using animal models have demonstrated that carbon dioxide (CO2) pneumoperitoneum during laparoscopy is associated with adverse physiological, metabolic, immunological and oncological effects, and many of these problems can be avoided by the use of helium insufflation. The present study was performed in patients to compare the effect of helium and CO2 insufflation on intraperitoneal markers of immunological and metabolic function.

METHODS

Eighteen patients undergoing elective upper gastrointestinal laparoscopic surgery were randomized to have insufflation achieved by using either helium (n = 8) or CO2 (n = 10) gas. Intraperitoneal pH was monitored continuously during surgery, and peritoneal macrophage function was determined by harvesting peritoneal macrophages at 5 min and 30 min after commencing laparoscopy, and then assessing their ability to produce tumour necrosis factor-alpha (TNF-alpha), and their phagocytic function.

RESULTS

Carbon dioxide laparoscopy was associated with a lower intraperitoneal pH at the commencement of laparoscopy, although this difference disappeared as surgery progressed. The production of TNF-alpha was better preserved by CO2 laparoscopy, but the insufflation gas used did not affect macrophage phagocytosis. Patients undergoing helium laparoscopy required less postoperative analgesia.

CONCLUSION

The choice of insufflation gas can affect intraperitoneal macrophage function in the clinical setting, and possibly acid-base balance. The present study suggested no immunological advantages for the clinical use of helium as an insufflation gas. The outcomes of the present study, however, are different to those obtained from previous laboratory studies and further research is needed to confirm this outcome.

Trocar site recurrence in laparoscopic surgery for colorectal cancer

BACKGROUND

Laparoscopic colorectal surgery has been associated with less postoperative pain, an early return of bowel function, a shorter period of hospitalization and disability, and better cosmetic results. However, the application of laparoscopic techniques to the curative resection of colorectal cancer is still controversial, owing to reports of cancer recurrence at the port site wounds. The accumulation of numerous such reports in a relatively short period raised concern that there might be an extraordinary high rate of port site metastases after laparoscopic colorectal surgery. This concern has led to intense clinical and basic research aimed at determining the incidence and causes of wound recurrence and developing preventative measures to address this problem. Despite these efforts, it is still not clear whether port site metastasis is really an inherent drawback to laparoscopic cancer surgery.

METHODS

In this review of the literature on port site metastasis, we gathered data from clinical series of laparoscopic surgery for colorectal cancer. We eliminated series of <50 patients, since they may be flawed by the learning curve required for this technically demanding procedure.

RESULTS

The rate of port site recurrences in the 1737 patients who participated in these series was 1%. Although the methods and criteria for patient selection in these studies varied, this figure appears to be comparable to the incidence reported for other malignancies and for laparotomies performed to treat colorectal cancer.

CONCLUSION

This review suggests that wound recurrence may actually be the result of an unfortunate learning curve, rather than an inherent concern. However, we must await the final results of large randomized studies before drawing any definitive conclusions.

Effect of laparotomy and laparoscopy on the establishment of lung metastasis in a murine model

BACKGROUND

Laparoscopic surgery is now applied to patients with gastrointestinal cancer. In animal studies, extraperitoneal tumor growth has been significantly less after laparoscopy than after laparotomy, but whether hematogenous metastasis occurs less frequently after laparoscopy is unknown. The aim of this study was to compare the frequency and growth of lung metastasis and serum levels of IL-6 and tumor necrosis factor-alpha (TNF-alpha) in mice treated by laparotomy and in mice treated by laparoscopy.

METHODS

We used 182 male BALB/c mice. Colon 26 cancer cells (5 x 10(4)) were injected into the tail vein, and the mice were assigned to a laparotomy group (3-cm laparotomy), a laparoscopy group (carbon dioxide pneumoperitoneum at 6 to 8 mm Hg for 30 minutes), or a control group. Lung weight, number of lung metastases, and serum levels of IL-6 and TNF-alpha were measured and compared among the 3 groups.

RESULTS

The lung weight and number of metastases on the lung surface and cut section in the laparotomy group (0.44+/-0.21 g, 55.7+/-46.7, 23.0+/-19.0) were significantly larger than those in the laparoscopy group (0.32+/-0.15 g, 29.9+/- 25.5, 13.1+/-9.9) or the control group (0.28+/-0.13, 29.3+/-26.2, 11.1+/-11.1). Three hours after the procedures, the serum level of IL-6 was significantly higher in the laparotomy group (1353 +/- 790 pg/mL) than in the laparoscopy group (671+/-353 pg/mL) or the control group (333+/-341 pg/mL). The lung weight, number of lung metastases, and levels of IL-6 and TNF-alpha were not different between the laparoscopy and control groups.

CONCLUSIONS

Our results indicate that, although laparotomy accelerates tumor metastasis to the lung in this murine model, laparoscopy does not increase the frequency and growth of lung metastasis. The laparoscopic approach may suppress hematogenous metastasis to the lung because of decreased surgical stress and reduced cytokine response.

Experimental study of effect of embolism of different laparoscopy insufflation gases

BACKGROUND AND PURPOSE

Whilst carbon dioxide is the gas generally used for insufflation during laparoscopy, several studies have reported adverse effects specifically associated with its use. These effects may be attributable to chemical, metabolic, or immunologic effects specific to CO2. Because helium is chemically, physiologically, and pharmacologically inert, it has been suggested as a possible substitute insufflation gas. However, there has been concern about the potential implications of venous gas embolism during helium insufflation. The aim of this study was to examine the physiological effect of the intravenous injection of He and CO2 in an experimental model.

MATERIALS AND METHODS

Eleven domestic white pigs were randomly allocated to receive multiple intravenous injections of increasing volumes of either CO2 or He gas. Cardiorespiratory function was measured, and the intravenous volumes of gas that resulted in cardiac arrest were determined.

RESULT

Cardiorespiratory functional measures returned to normal quicker after CO2 than after He injection. Helium injection quickly overwhelmed the animal's ability to compensate and resulted in death at a lower volume than did CO2 injection.

CONCLUSIONS

Gas embolism during He insufflation is more likely to be lethal than is CO2 embolism. This scenario is most likely following Veress needle insertion into a large vein. Therefore, if He is to be used for insufflation during clinical laparoscopy, the possibility of venous injection should be minimized by avoiding Veress needle use. Further investigation of the safety of He insufflation is warranted before a role during clinical laparoscopy can be recommended.

Cancer and laparoscopy, experimental studies: a review

OBJECTIVE

To review the experimental studies on laparoscopy and cancer and to propose guidelines for the clinical management of gynecologic cancer.

METHODS

The literature in MEDLINE was searched from January 1992 to December 1998 using the terms 'cancer', 'laparoscopy' and 'experimental or animal study'. Cross-referencing identified additional publications. Abstracts and letters to the editor were excluded. All the relevant papers were reviewed.

RESULTS

Depending on the model used, controversial results have been reported on the incidence of trocar site metastasis when comparing CO(2) laparoscopy and laparotomy. In contrast, the following conclusions can be proposed: (i) tumour growth after laparotomy is greater than after endoscopy; (ii) tumour dissemination is worse after CO(2) laparoscopy than after laparotomy; (iii) some of the disadvantages of CO(2) laparoscopy may be treated using local or intravenous treatments or avoided using other endoscopic exposure methods, such as gasless laparoscopy.

CONCLUSIONS

The laparoscopic treatment of gynecologic cancer has potential advantages and disadvantages, and may only be performed in prospective clinical trials. The risk of dissemination appears high when a large number of malignant cells are present. Adnexal tumours with external vegetations, and bulky lymph nodes should be considered as contra-indications to CO(2) laparoscopy.

Office transvaginal hydrolaparoscopy for early diagnosis of pelvic endometriosis and adhesions

STUDY OBJECTIVE. To evaluate the feasibility of a new endoscopic technique, transvaginal hydrolaparoscopy, for early office screening of subfertile women. DESIGN. Retrospective, descriptive feasibility study (Canadian Task Force classification II-2).

SETTING

Office in an infertility center.

PATIENTS

One hundred fifty-seven continuous women with primary or secondary subfertility.

INTERVENTION

Under local anesthesia, a Veress needle-cannula system was inserted into the posterior fornix with peritoneal distention by saline.

MEASUREMENTS AND MAIN RESULTS

Access was achieved in 95% of patients. In 58.5% the findings were normal and in 28% an explorative or operative laparoscopy was indicated. No major complication occurred. Patients' pain scores were similar to those for office hysteroscopy.

CONCLUSION

Transvaginal hydrolaparoscopy was successfully performed in the office. The technique allows early and complete endoscopic screening of subfertile women.

Office hydrolaparoscopy for the diagnosis of endometriosis and tubal infertility

Transvaginal hydrolaparoscopy has been described as an office procedure that is particularly suitable for the diagnosis of endometriosis and adhesions. It is recommended as a first line procedure in patients with infertility. The procedure is performed under local anaesthesia or sedation in an office setting. The abdominal distension is achieved by transvaginal instillation of warm saline using a combined Veress needle-trocar system. The exploration under fluid allows the inspection of the tubo-ovarian structures in their natural position and the easy identification of endometriotic lesions and adhesions in the posterior pelvis. The limitation of the inspection to the posterior pelvis is not a major problem for the diagnosis of endometriosis because exclusively anterior pelvis endometriosis is rare and of doubtful significance in infertility. Transvaginal hydrolaparoscopy can be performed in the office setting in combination with minihysteroscopy, tubal patency test and salpingoscopy, offering major advantages for the diagnosis of pelvic disease in patients with infertility.

Experimental study of the effect of intraperitoneal heparin on tumour implantation following laparoscopy

BACKGROUND

Conclusions drawn from clinical reports of port site metastases following laparoscopic resection of intra-abdominal malignancy are now supported by a burgeoning experimental literature which suggests that laparoscopy promotes tumour metastasis to wounds. This study investigated the effect of intraperitoneal blood and heparin on the incidence of tumour cell implantation and port site metastasis.

METHODS

Twenty-four Dark Agouti rats underwent laparoscopy with carbon dioxide insufflation and the instillation of a tumour cell suspension and/or blood into the peritoneal cavity. Rats were allocated randomly to one of the following study groups (six rats per group): (1) controls; (2) intraperitoneal blood (2 ml blood introduced from a syngeneic donor rat); (3) intraperitoneal heparin; (4) intraperitoneal blood and heparin. Rats were killed 7 days after the procedure, and the peritoneal cavity and port sites were examined for the presence of tumour.

RESULTS

Tumour implantation and port site metastases were reduced by the intraperitoneal administration of heparin, but increased by the presence of intraperitoneal blood.

CONCLUSION

The results of this study suggest that tumour implantation following laparoscopy is promoted by the presence of intraperitoneal blood and that this effect may be reduced by the use of intraperitoneal heparin.

Review of investigations regarding the etiology of port site tumor recurrence

The animal and human studies presented, at first glance, present a confusing and conflicting story. In regards to the animal studies, much of this confusion can be traced to the use of a variety of different models, none of which truly reproduces the human situation. Nonetheless, there is much to be gleaned from these efforts. The authors present conceptualization of the port wound tumor dilemma follows. In order for wound tumors to develop, viable tumor cells must be liberated from the primary tumor and find transport to a wound. Rarely, patients with colon tumors will present with or will develop widespread intraabdominal carcinomatosis. These tumors have the ability to spontaneously shed considerable numbers of viable cells which have the ability to implant on uninjured peritoneal surfaces. Unfortunately, the surgeon has little chance for success in these patients with either open or minimally invasive methods. Fortunately, most colon adenocarcinomas do not spread in this manner. Differences in the clinical behavior and manifestations of colon tumors most likely reflect the genetic makeup of individual tumors. Colonic neoplasm's ability to invade and metastasize varies considerably from tumor to tumor. Thankfully, as mentioned, the vast majority of colon tumors are not prone to cause carcinomatosis. Despite this fact, the human data available suggests that tumor cells can be found in the peritoneal cavity using sophisticated methods in about half of the patients after colectomy. If this is the case, then why aren't more wound tumors seen? Logic dictates that there must be a critical number of free intraabdominal cells above which successful wound seeding is likely. It makes sense that traumatization of the tumor will result in increased numbers of liberated cells. Therefore, surgical approach and technique should impact considerably on outcome. For the majority of colon tumors, if the lesion is assiduously avoided during mobilization and resection, it is unlikely that enough tumor cells will be shed to result in port site tumors. The recent interim results of the Cleveland Clinic's and the Barcelona randomized trials certainly support such a hypothesis. With over 300 patients enrolled (combined series) and with an average follow up of over 2 years, in neither trial has a port site tumor been noted. Similarly, with an average follow up of just under 3 years, Franklin et al noted that there were no port site tumors in their prospective trial of 191 consecutive laparoscopic colectomies for cancer. In the clinical setting, experience and surgical expertise seem to be the best predictor of outcome, in regards to wound tumors. The few animal studies that allow assessment of the impact of technique (i.e. those that utilize an intraabdominal solid tumor model which allows tumor excision) indeed support this hypothesis. In these studies poor technique resulted in significantly more wound tumors. Furthermore, it has been shown that for laparoscopic procedures, there is a definite learning period during which the incidence of wound tumors is considerably higher than that of open resection. With experience the laparoscopic incidence falls to that of open resection. Furthermore, a number of recent studies suggest that is possible to lower the incidence of wound tumors via peritoneal and wound irrigation with a variety of agents. These animal study results are in keeping with the recent clinical results. Both would suggest that given proper and adequate training and with sufficient attention being paid to avoid tumor handling that the incidence of wound tumors will be as low as that following open colectomy. How large a part, if any, does the CO2 pneumoperitoneum play in the port wound tumor story? Certainly, the results of the bulk of the animal studies performed, to date, have suggested that the CO2 pneumoperitoneum plays a critical role in the development of port wound tumors. With few exceptions, these studies have utilized tumor cel