Gastric lymphatic mapping for sentinel node biopsy by natural orifice transluminal endoscopic surgery (NOTES)

Techniques and Current Role of Sentinel Lymph Node (SLN) Concept in Gastric Cancer Surgery

Gastric cancer patients represent a rather divergent patient group and in certain carefully selected cases of early forms of gastric cancer the D2 gastrectomy could be considered a more radical procedure than the biological and oncological characteristics of the primary tumor on the gastric wall would require. As any unnecessary dissection increases morbidity without always respective survival benefits, an approach that could accurately predict and actually dictate the exact extent of lymph node dissection would be ideal. It is more than logical the assumption that the standard D2 lymphadenectomy could represent an overtreatment in distinct patients groups such as patients with early gastric cancer with favorable pathological characteristics and clinically negative nodes not suitable for endoscopic treatment because this early stage disease shows limited lymph node metastasis incidence and excellent overall survival. Considering that the D2 gastrectomy has a negative impact on the quality of life of gastric cancer patients due to the post-gastrectomy functional results, a concept of a more targeted lymph node dissection, when appropriate, is certainly appealing. It is yet to be proven whether sentinel lymph node navigation surgery can fulfill such expectations providing the appropriate balance between morbidity and oncological safety in selected gastric cancer patients.

Sentinel node navigation surgery in gastric cancer: Current status

The theory behind using sentinel node mapping and biopsy in gastric cancer surgery, the so-called sentinel node navigation surgery, is to limit the extent of surgical tissue dissection around the affected organ and subsequently the accompanied morbidity. However, obstacles on the clinical correspondence of sentinel node navigation surgery in everyday practice have occasionally alleviated researchers’ interest on the topic. Only recently with the widespread use of minimally invasive surgical techniques, i.e., laparoscopic gastric cancer resections, surgical community’s interest on the topic have been unavoidably reflated. Double tracer methods appear superior compared to single tracer techniques. Ongoing research is now focused on the invention of new lymph node detection methods utilizing sophisticated technology such as infrared ray endoscopy, florescence imaging and near-infrared technology. Despite its notable limitations, hematoxylin/eosin is still the mainstay staining for assessing the metastatic status of an identified lymph node. An intra-operatively verified metastatic sentinel lymph node will dictate the need for further conventional lymph node dissection. Thus, laparoscopic resection of the gastric primary tumor combined with the appropriate lymph node dissection as determined by the process of sentinel lymph node status characterization represents an option for early gastric cancer. Patients with T3 or more advanced disease should still be managed conventionally with resection plus standard lymph node dissection.

Natural-orifice translumenal endoscopic surgery (NOTES): minimally invasive evolution or revolution?

Since the first animal experimental laparoscopy in 1902, minimal access techniques have revolutionized surgery. Using the natural orifice dates back to at least the second century when Soranus performed a vaginal hysterectomy. The main difference between traditional endolumenal surgery and the translumenal approach of natural-orifice translumenal endoscopic surgery (NOTES) is the intentional puncture of a healthy organ in NOTES to access a cavity or other organ. The aim of this review was to examine the past, present, and potential future role of NOTES in the context of other developments in minimal access surgery. NOTES is at an early stage in its development and a convincing benefit over laparoscopy has not been demonstrated. Concerns regarding complications, for example of viscerotomy closure, have limited the widespread uptake of pure NOTES. However, it is likely that technological advances for NOTES surgery will enhance conventional laparoscopic and endoscopic techniques.

A comparison of five competing lymph node staging schemes in a cohort of resectable gastric cancer patients

BACKGROUND

New classifications for lymph node (LN) staging have recently been proposed to improve upon the UICC/AJCC N category staging convention. Ratio-based systems and logarithmic odds (LODDS) scores are two families of novel competing staging systems. We compared UICC/AJCC staging with 5 ratio and LODDS systems in predicting overall survival (OS) in patients with resected gastric cancer.

METHODS

Using a large population-based dataset, we identified 12,184 nonmetastatic resectable gastric cancer patients between 1988 and 2004. We compared each subject's UICC/AJCC N stage with five novel staging schemes. We analyzed the OS for each method. Our comparison metric was the log-rank Chi squared statistic; larger Chi squared statistics indicate improvements in N stage discrimination.

RESULTS

Median OS was 2.1 years (95 % CI 2.0-2.2 years), while median patient follow-up for surviving patients was 8.3 years (range, 1 month-22 years). Although all 5 staging systems were either comparable or superior to the UICC/AJCC convention, a LN ratio method outperformed others in N stage discrimination based on log-rank tests for OS. This trend was independent of the number of LNs examined.

CONCLUSIONS

Novel LN staging methods have a higher degree of discrimination utility than the UICC/AJCC N convention. These methods may have a role in reducing the prognostic impact of LN count variability. Of the systems assessed, the LN ratio system that assigns greater risk attribution to cases with <16 LNs was the best classification method to predict OS in patients with resectable gastric cancer.

Gastric surgery and notes

Rather than being an end point in and of itself, NOTES offers an approach that encompasses the potential use of a natural orifice in conjunction with flexible instruments as a less invasive and more cosmetically appealing method of performing certain surgical procedures. Gastric surgery through natural orifices is one of the cutting-edge procedures in the evolving field of NOTES. The potential indications for NOTES involve a wide spectrum of upper gastrointestinal diseases, including achalasia, reflux disease, submucosal tumors, cancer, and morbid obesity. Although NOTES is becoming more widely used, most studies still involve only small numbers of patients, and the design of larger series and comparative trials to evaluate the early indications and results of NOTES is needed.

Interventional endoscopy and single incision surgery

The following on interventional endoscopy and single incision surgery contains commentaries on transluminal endoscopic esophageal surgery, flexible endoscopy, triangulation, advanced flexible operating platforms, experimental transesophageal procedures, and para- and intra-esophageal endoscopic surgery.

Gastric adenocarcinoma surgery and adjuvant therapy

Gastric adenocarcinoma is one of the most common causes of death worldwide. Surgical resection remains the mainstay of therapy, offering the only chance for complete cure. Resection is based on the principles of obtaining adequate margins, with the extent of lymphadenectomy remaining controversial. Neoadjuvant and adjuvant therapies are used to reduce local recurrence and improve long-term survival. This article reviews the literature and provides a summary of surgical management options and neoadjuvant/adjuvant therapies for gastric adenocarcinoma.

Sentinel lymph node biopsy for gastric cancer: Where do we stand?

Development of sentinel node navigation surgery (SNNS) and advances in minimally invasive surgical techniques have greatly shaped the modern day approach to gastric cancer surgery. An extensive body of knowledge now exists on this type of clinical application but is principally composed of single institute studies. Certain dye tracers, such as isosulfan blue or patent blue violet, have been widely utilized with a notable amount of success; however, indocyanine green is gaining popularity. The double tracer method, a synchronized use of dye and radio-isotope tracers, appears to be superior to any of the dyes alone. In the meantime, the concepts of infrared ray electronic endoscopy, florescence imaging, nanoparticles and near-infrared technology are emerging as particularly promising alternative techniques. Hematoxylin and eosin staining remains the main method for the detection of sentinel lymph node (SLN) metastases. Several specialized centers have begun to employ immunohistochemical staining for this type of clinical analysis but the equipment costs involving the associated ultra-rapid processing systems is limiting its widespread application. Laparoscopic function-preserving resection of primary tumor from the stomach in conjunction with lymphatic basin dissection navigated by SLN identification represents the current paramount of SNNS for early gastric cancer. Patients with cT3 stage or higher still require standard D₂ dissection.

Critical analysis of hot topics in NOTES

Natural orifice transluminal endoscopic surgery (NOTES) has gained a great deal of attention from gastroenterologists and surgeons all over the world since its introduction in 2000. The field of NOTES has advanced tremendously since that time and exciting and well-designed research has been reported. Both randomized controlled trials and results from large national and international registries have been published. Many experimental and clinical studies have discussed transesophageal, transgastric, transvaginal and transrectal access for a variety of NOTES procedures. Transvaginal access has been the most frequently reported NOTES access route in clinical trials. When suitable instruments become available, a true comparison of NOTES with current laparoscopic approaches can be realized.

Full-thickness laparoendoscopic excision in the stomach: the FLEx technique

BACKGROUND

The authors describe the initial validation of a novel full-thickness laparoendoscopic excision (FLEx) technique for the stomach.

METHODS

The technique was studied in seven 50-kg pigs. Secure full-thickness excision was ensured by inversion excision target with a 1-cm circumferential margin using laparoendoscopically placed brace bars passed intraluminally from the outside of the stomach, laparoscopic oversewing of the site of inversion, and endoscopic full-thickness excision using a dual scope approach. Pigs were sacrificed either immediately (n = 3) or between 7 and 10 days after surgery (n = 4).

RESULTS

The procedure achieved uncomplicated full-thickness excision in every case. Median procedure duration was 227 minutes (range = 210-245 minutes). Median specimen diameter was 5.5 cm (range = 2.5-8 cm). Investigative autopsy confirmed technical sufficiency in all animals. Median site bursting pressure was 130 mm Hg (range = 120-160 mm Hg).

CONCLUSIONS

The FLEx technique proved useful for excision of small localized lesions of the stomach in this animal study.

Gastric lymphatic basin dissection for sentinel node biopsy using hybrid natural orifice transluminal endoscopic surgery (NOTES)

The aim of the present study was to describe a method of gastric lymphatic basin dissection for sentinel node biopsy using natural orifice transluminal endoscopic surgery with laparoscopic assistance (hybrid NOTES) in a porcine model. Lymph node dissection was performed in three healthy female domestic farm pigs (each around 40 kg) between October, 2007, and December, 2007. The pigs were administered a general anesthetic and laparoscopy-guided transvaginal colpotomy was performed. A two-channel endoscope was then inserted through the incision into the peritoneal cavity via the transvaginal route. An endoscope was inserted simultaneously into the mouth and indocyanine green solution was injected into the submucosal layer of the gastric wall at four sites. Dyed omentum and lymphatics were dissected using a laparoscopic dissector and the grasping forceps of a transvaginal endoscope. Lymphatics and omentum (mean 13.3 cm, range 8-20 cm) were removed transvaginally. The mean number of detected and resected sentinel nodes was 2.6 (range 1-4, diameter 2~12 mm). Sentinel lymphatic basin dissection was performed successfully and without intraoperative complications in all three cases. Hybrid NOTES is technically feasible, and this procedure may represent an alternative to laparoscopic sentinel lymph node dissection of the stomach.

Natural orifice translumenal endoscopic surgery

PURPOSE OF REVIEW

Since its introduction in 2000, natural orifice translumenal endoscopic surgery (NOTES) has gained a great deal of attention from gastroenterologists and surgeons all over the world. In this article, we will review the progress in the field of NOTES and present the latest publications that provide some answers and solutions to the barriers suggested by the Natural Orifice Surgery Consortium for Assessment and Research white paper.

RECENT FINDINGS

Because of the first human NOTES procedure by Rao and Reddy, more pioneering procedures, including transgastric and transvaginal cholecystectomies, appendectomies, and hernia repairs, have been performed. Although NOTES researchers continue to experiment with new innovative equipment and procedures in the lab, more structured work, including randomized controlled trials, has been published.

SUMMARY

In the last several years, there has been growing interest in NOTES, which has translated into exciting animal research work and publication of randomized controlled trials. Additionally, preliminary NOTES human procedures have been successfully performed. When suitable instruments become available, the subsequent step should be comparing NOTES with current laparoscopic approaches. Superiority or even equality of NOTES to laparoscopic surgery would be the best argument for advancing and integrating implementation into clinical practice.

NOTES: The question for minimal resection and sentinel node in early gastric cancer

Surgical therapy for gastric cancer involves both removal of the cancer lesion and complete lymph node dissection. Natural orifice transluminal endoscopic surgery (NOTES) is considered to represent the next revolution in surgery. Many surgeons and endoscopists believe that NOTES may be a superior alternative for early gastric cancer treatment. Sentinel node (SN) navigation surgery for gastric cancer: Single institution results of SN mapping for early gastric cancer are increasingly being considered acceptable. Furthermore, a major large-scale clinical trial of SN mapping for gastric cancer has recently been completed by The Japan Society of SN Navigation Surgery study group. They reported false negative rate of 7.0% while the sensitivity of metastasis detection based on SN status was 93%. Combination of SN biopsy and NOTES: This concept was first described by Cahill et al who proved the feasibility of lymphatic mapping and SN biopsy by NOTES. Lymphatic channel filling was immediately observable via the intraperitoneal optics. Partial resection of the stomach by hybrid NOTES: Several centers have already reported gastrectomy assisted by NOTES using the transvaginal route. However, the main problem of full-thickness resection of gastric wall remains endoscopic gastric closure. Establishing an endoscopic suturing method would be an important step toward expanding potential indications. NOTES is met with both enthusiasm and skepticism but will gain its own place as human creativity eventually provides solutions to its technical limitations. In the near future, NOTES can evolve the capacity to complement the existing armamentarium for gastric cancer surgery.

Transgastric cholecystectomy: From the laboratory to clinical implementation

After the first report by Kalloo et al on transgastric peritoneoscopy in pigs, it rapidly became apparent that there was no room for an under-evaluated concept and blind adoption of an appealing (r)evolution in minimal access surgery. Systematic experimental work became mandatory before any translation to the clinical setting. Choice and management of the access site, techniques of dissection, exposure, retraction and tissue approximation-sealing were the basics that needed to be evaluated before considering any surgical procedure or study of the relevance of natural orifice transluminal endoscopic surgery (NOTES). After several years of testing in experimental labs, the revolutionary concept of NOTES, is now progressively being experimented on in clinical settings. In this paper the authors analyse the challenges, limitations and solutions to assess how to move from the lab to clinical implementation of transgastric endoscopic cholecystectomy.

Natural orifice transluminal endoscopic surgery--here and now

Natural Orifice Transluminal Endoscopic Surgery (NOTES) has captured the attention of physicians and patients alike. Although clinical experience remains limited as technological capacity lags someway behind concept, this revolutionary approach is already prompting reassessment of conventional surgical dogma. Indeed, this very aspect may in fact represent the greatest legacy of current endeavour aimed at progressing natural orifice intervention as the biological insights so gleaned may then be used to help hone standard operations further towards perfection. As a corollary, rather than viewing it as a mere means of reformatting laparoscopic operation without the abdominal wall access component, NOTES should be investigated fully from the perspective of how it may complement (rather than compete with) current conventional techniques. In this way patients may in due course be allowed benefit by selection of the procedure of 'best fit' from an expanded array of surgical interventions. A clear focus on identifying specific clinical niches that are currently imperfectly addressed would also considerably advance the rationale for new surgical innovations such as NOTES and allow them to be engineered in the directions most likely to result in therapeutic advance. Thus while NOTES approaches for operations for neoplasia of the colon and even rectum clearly require more nuanced deliberation and care than does for example cholecystectomy for uncomplicated cholelithiasis, the gain from such investment seems likely to more considerably aid both the development and stature of NOTES as well as providing the greater likelihood of clinical progress for our patients.

Natural orifice translumenal endoscopic surgery (NOTES) applied totally to sigmoidectomy: an original technique with survival in a porcine model

BACKGROUND

Natural orifice translumenal endoscopic surgery (NOTES) continues to evolve. This study investigated the feasibility and outcome of performing localized sigmoidectomy in its entirety via NOTES.

METHODS

A survival study of five male minipigs (mean weight, 30 kg) was conducted. After anesthesia, a gastrotomy was created by a per os double-channel endoscope, and full peritoneoscopy was performed. A Berci needle then was inserted transparietally to allow maintenance and monitoring of the pneumoperitoneum. Using a transanal probe to facilitate intestinal retraction, the mesentery was dissected with instruments worked through the channels of the transgastric endoscope. The anvil of a circular stapler then was passed per anum into the colon above the point of intended transection. A penetrating transrectal trocar was placed to allow entry of a linear stapler into the peritoneum through a colotomy, and the sigmoid was cross-stapled proximally. The strut of the anvil then was snugged into a colotomy made at this staple line. The specimen was delivered via the anus by a "pull-through" technique. The distal sigmoidal margin was cross-stapled extracorporeally, ensuring that the colotomy was included within the specimen. Retrograde passage of the circular stapler head per anus allowed colocolonic reanastomosis by its mating with the anvil already in situ. The gastrotomy was closed with a previously validated prosthesis. Postoperatively, all the animals were recovered and monitored for well-being during convalescence. Endoscopy (gastroscopy and sigmoidoscopy), laparoscopy, and laparotomy were performed on postoperative day 14 as follow-up measures.

RESULTS

Each operation was satisfactorily completed. The mean operative time was 76 min (range, 44-95 min). All the animals prospered postoperatively. Follow-up examination showed full healing of all anastomoses and gastrotomy sites. There was no evidence of luminal stricturing, peritonitis, or intraabdominal sepsis in any animal.

CONCLUSIONS

Using this experimental model, colonic resection and reanastomosis can be performed safely within the NOTES format.