Optimal settings and accuracy of indocyanine green fluorescence imaging for sentinel node biopsy in early gastric cancer

Appropriate concentration setting for the intraoperative administration of indocyanine green for fluorescence imaging to identify the sentinel lymph node in early gastric cancer: a clinical pilot study

PURPOSE

Some prospective trials have demonstrated the feasibility of sentinel node (SN) biopsy in gastric cancer (GC) surgery. This study aimed to identify the appropriate concentration settings for the intraoperative injection of indocyanine green (ICG) for SN biopsy.

METHODS

Before the clinical studies, porcine model experiments explored the optimal concentration of ICG injected intraoperatively. Next, nine GC patients were enrolled in the clinical research. ICG (0.5 ml) was injected intraoperatively into four quadrants of the submucosa around the tumor at various concentrations (0.5, 0.25, and 0.1 mg/ml). The lymphatic basin dissection method was applied to the ICG-positive lymphatic areas. The number and location of the lymphatic basins and positive nodes were recorded intraoperatively.

RESULTS

In the porcine model, the visibility gradually became clear at an ICG concentration higher than 0.1 mg/ml. In the clinical study, the average number of detected lymphatic basins was 3.3, 1.7, and 1.7, respectively. The mean number of detected SNs was 14.7, 6.7, and 4.0, respectively.

CONCLUSION

To improve the reproducibility of SN biopsy, it is essential to prepare the correct concentration setting of ICG. Under current conditions in which ICG is injected intraoperatively, a 0.1 mg/ml concentration setting of ICG may be necessary and sufficient for SN identification.

Application value of indocyanine green fluorescence imaging in guiding sentinel lymph node biopsy diagnosis of gastric cancer: Meta-analysis

BACKGROUND

Gastric cancer is a common malignant tumor of the digestive system worldwide, and its early diagnosis is crucial to improve the survival rate of patients. Indocyanine green fluorescence imaging (ICG-FI), as a new imaging technology, has shown potential application prospects in oncology surgery. The meta-analysis to study the application value of ICG-FI in the diagnosis of gastric cancer sentinel lymph node biopsy is helpful to comprehensively evaluate the clinical effect of this technology and provide more reliable guidance for clinical practice.

AIM

To assess the diagnostic efficacy of optical imaging in conjunction with indocyanine green (ICG)-guided sentinel lymph node (SLN) biopsy for gastric cancer.

METHODS

Electronic databases such as PubMed, Embase, Medline, Web of Science, and the Cochrane Library were searched for prospective diagnostic tests of optical imaging combined with ICG-guided SLN biopsy. Stata 12.0 software was used for analysis by combining the "bivariable mixed effect model" with the "midas" command. The true positive value, false positive value, false negative value, true negative value, and other information from the included literature were extracted. A literature quality assessment map was drawn to describe the overall quality of the included literature. A forest plot was used for heterogeneity analysis, and P < 0.01 was considered to indicate statistical significance. A funnel plot was used to assess publication bias, and P < 0.1 was considered to indicate statistical significance. The summary receiver operating characteristic (SROC) curve was used to calculate the area under the curve (AUC) to determine the diagnostic accuracy. If there was interstudy heterogeneity (I 2 > 50%), meta-regression analysis and subgroup analysis were performed.

RESULTS

Optical imaging involves two methods: Near-infrared (NIR) imaging and fluorescence imaging. A combination of optical imaging and ICG-guided SLN biopsy was useful for diagnosis. The positive likelihood ratio was 30.39 (95%CI: 0.92-1.00), the sensitivity was 0.95 (95%CI: 0.82-0.99), and the specificity was 1.00 (95%CI: 0.92-1.00). The negative likelihood ratio was 0.05 (95%CI: 0.01-0.20), the diagnostic odds ratio was 225.54 (95%CI: 88.81-572.77), and the SROC AUC was 1.00 (95%CI: The crucial values were sensitivity = 0.95 (95%CI: 0.82-0.99) and specificity = 1.00 (95%CI: 0.92-1.00). The Deeks method revealed that the "diagnostic odds ratio" funnel plot of SLN biopsy for gastric cancer was significantly asymmetrical (P = 0.01), suggesting significant publication bias. Further meta-subgroup analysis revealed that, compared with fluorescence imaging, NIR imaging had greater sensitivity (0.98 vs 0.73). Compared with optical imaging immediately after ICG injection, optical imaging after 20 minutes obtained greater sensitivity (0.98 vs 0.70). Compared with that of patients with an average SLN detection number < 4, the sensitivity of patients with a SLN detection number ≥ 4 was greater (0.96 vs 0.68). Compared with hematoxylin-eosin (HE) staining, immunohistochemical (+ HE) staining showed greater sensitivity (0.99 vs 0.84). Compared with subserous injection of ICG, submucosal injection achieved greater sensitivity (0.98 vs 0.40). Compared with 5 g/L ICG, 0.5 and 0.05 g/L ICG had greater sensitivity (0.98 vs 0.83), and cT1 stage had greater sensitivity (0.96 vs 0.72) than cT2 to cT3 clinical stage. Compared with that of patients ≤ 26, the sensitivity of patients > 26 was greater (0.96 vs 0.65). Compared with the literature published before 2010, the sensitivity of the literature published after 2010 was greater (0.97 vs 0.81), and the differences were statistically significant (all P < 0.05).

CONCLUSION

For the diagnosis of stomach cancer, optical imaging in conjunction with ICG-guided SLN biopsy is a therapeutically viable approach, especially for early gastric cancer. The concentration of ICG used in the SLN biopsy of gastric cancer may be too high. Moreover, NIR imaging is better than fluorescence imaging and may obtain higher sensitivity.

Da Vinci robot-assisted endoscopic full-thickness gastric resection with regional lymph node dissection using a 3D near-infrared video system: a single-center 5-year clinical outcome

BACKGROUND

Endoscopic full-thickness gastric resection (EFTGR) with regional lymph node dissection (LND) has been used for early gastric cancer (EGC) exceeding the indications for endoscopic submucosal dissection (ESD). The extent of the dissected lymph nodes is crucial. A 3D near-infrared (NIR) video robot system significantly enhances visualization of the lymphatic system. However, this system has not been used in EFTGR with LND. Thus, this study assessed the benefits of the 3D NIR video robot system in a clinical setting.

METHODS

Between February 2015 and September 2018, 24 patients with EGC exceeding the indications for ESD were treated with EFTGR and LND using a 3D NIR video system with the da Vinci surgical robot. Indocyanine green (ICG) was injected endoscopically around the tumor, and basin node (BN) dissection around the nodes was examined using the 3D NIR video system of the da Vinci Si surgical robot. Subsequently, robot-assisted EFTGR was performed. The primary outcome was the 5-year survival rate.

RESULT

During a 5-year follow-up of all 24 patients, an 80-year-old patient with an ulcer and T2 invasion was lost to follow-up. Among the remaining 23 patients, no mortality or recurrence was observed.

CONCLUSION

No metastasis or mortality occurred using the da Vinci robot-assisted EFTGR with LLND and a 3D NIR video system for patients who required radical gastrectomy for EGC in over 5 years. Hence, this may be a safe and effective method for radical gastrectomy; further studies are required confirming its effectiveness.

Long‑term survival prognosis of function‑preserving curative gastrectomy for early gastric cancer

Segmental gastrectomy, mini-distal gastrectomy and local resection of the stomach are function-preserving curative gastrectomies (FPGs), which are used to treat gastric cancer in specialized centers. These surgical options are less invasive and can alleviate postgastrectomy symptoms more than standard gastrectomy; however, their association with prognosis remains to be fully elucidated. The present study aimed to compare the survival prognosis of patients diagnosed as node-negative by sentinel node biopsy (SNB) treated via FPG with reduced lymph node dissection with that of patients who underwent guideline gastrectomy (GL). This retrospective study was conducted between April 1999 and March 2016. The inclusion criteria were a diagnosis of gastric cancer type 0, of ≤5 cm, located in L or M areas, and pT1N0. Patients who underwent distal gastrectomy and pylorus-preserving gastrectomy were included as controls in the GL group. Among the 146 and 300 patients in the FPG and GL groups, respectively, only 1 patient in the GL group experienced recurrence. The overall survival (OS) of the FPG group was 96.6% at 5 years and 92.5% at 10 years, which was significantly higher than that of the GL group (P<0.05). In addition, the cumulative incidence of non-cancer-related deaths, especially pulmonary diseases, was lower in the FPG group than that in the GL group (P<0.05). Notably, the OS and non-cancer death rate in the FPG group remained significantly better after propensity score-matching analysis. In conclusion, for early gastric cancer located in M or L areas, patients treated via FPG guided by SNB have a better prognosis and fewer deaths caused by respiratory disease than those treated via GL. The present clinical trial was registered under the following trial registration numbers: UMIN000010154 (2013/3/4), UMIN000023828 (2016/8/29), jRCTs041180006 (2018/10/9).

Endoscopic fluorescent lymphography for gastric cancer

Lymphography by radioisotope or dye is a well-known technique for visualizing the lymphatic drainage pattern in a neoplastic lesion and it is in use in gastric cancer. Indocyanine green (ICG) more recently has been validated in fluorescent lymphography studies and is under evaluation as a novel tracer agent in gastric cancer. The amount and dilution of ICG injected as well as the site and the time of the injection are not standardized. In our unit, endoscopic submucosal injections of ICG are made as 0.5 mg in 0.5 mL at four peritumoral sites the day before surgery (for a total of 2.0 mg in 2.0 mL). Detection instruments for ICG fluorescence are evolving. Near-infrared systems integrated into laparoscopic or robotic instruments (near-infrared fluorescence imaging) have shown the most promising results. ICG fluorescence recognizes the node that receives lymphatic flow directly from a primary tumor. This is defined as the sentinel lymph node, and it has a high predictive negative value at the cT1 stage, able to reduce the extent of gastrectomy and lymph node dissection. ICG also enhances the number of lymph nodes detected during extended lymphadenectomy for advanced gastric cancer. Nevertheless, the practical effects of ICG use in a single patient are not yet clear. Standardization of the technique and further studies are needed before fluorescent lymphography can be used extensively worldwide. Until then, current guidelines recommend an extensive lymphadenectomy as the standard approach for gastric cancer with suspected metastasis.

Opportunities of ICG-fluorescent imaging of lymph nodes during radical cystectomy in patients with bladder cancer: A review

Today, the "golden standard" for the treatment of aggressive forms of bladder cancer is radical cystectomy. An important stage is the pelvic lymphadenectomy. This procedure is crucial for staging the tumor process, determining the subsequent treatment tactics and improving the results of surgery. Currently, the concept of a signaling lymph node (LN) is actively developing, which allows reducing the necessary level of dissection of the pelvic LN. Reducing the number of resected LN increases the level of surgical safety of the patient. The leading method of intraoperative visualization of signal LN is the fluorescence of indocyanine green in the near infrared range of the spectrum. The prospects of this diagnostic method for radical cystectomy in patients with bladder cancer determine the vector of future scientific research in this area.

Recent Advances in Sentinel Node Navigation Surgery for Early Gastric Cancer

Maintaining the postoperative quality of life (QOL) while ensuring curability without overtreatment is important in the treatment of early gastric cancer. Postoperative QOL is anticipated to be maintained through minimally invasive function-preserving gastrectomy in early gastric cancer. The concept of the sentinel lymph node (SN) basin is essential to maintain the curability of early gastric cancer using minimally invasive function-preserving gastrectomy. However, additional resection after surgery is difficult to perform in gastric cancer. Thus, the SN basin theory is important. Recently, a multicenter randomized phase III trial in South Korea (SENORITA trial) proved that laparoscopic sentinel node navigation surgery (LSNNS) for stomach preservation results in better postoperative QOL compared with standard gastrectomy in patients with early gastric cancer. LSNNS contributes to patients' QOL based on the concept that curability is not impaired. A multicenter nonrandomized phase III trial is ongoing in Japan, and oncologic safety is expected to be demonstrated. LSNNS has been established as a treatment option for selected patients with early gastric cancer, and its application will become widespread in the future.

Use of fluorescence imaging and indocyanine green for sentinel node mapping during gastric cancer surgery: Results of an intercontinental Delphi survey

BACKGROUND

Understanding the extent of tumor spread to local lymph nodes is critical to managing early-stage gastric cancer. Recently, fluorescence imaging with indocyanine green has been used to identify and characterize sentinel lymph nodes during gastric cancer surgery, but no published guidelines exist. We sought to identify areas of consensus among international experts in the use of fluorescence imaging with indocyanine green for mapping sentinel lymph nodes during gastric-cancer surgery.

METHODS

In this 2-round, online Delphi survey, 27 international experts voted on 79 statements pertaining to patient preparation and contraindications to fluorescence imaging with indocyanine green during gastric cancer surgery; indications; technical aspects; advantages/disadvantages and limitations; and training and research. Methodological steps were adopted during survey design to minimize bias.

RESULTS

Consensus was reached on 61 of 79 statements, including giving single injections of indocyanine green into each of the 4 quadrants peritumorally, administering indocyanine green on the same day as surgery, injecting a total of 1 to 5 mL of 5 mg/mL indocyanine green, injecting endoscopically into submucosa, and repeating indocyanine green injections a second time if sentinel lymph node visualization remains inadequate. Consensus also was reached that fluorescence imaging with indocyanine green is an acceptable single-agent modality for sentinel lymph node identification and that the sentinel lymph node basin method is preferred. However, sentinel lymph node dissection should be limited to T1 gastric cancer and tumors ≤4 cm in diameter, and further research is necessary to optimize the technique and render fluorescence-guided sentinel lymph nodes dissection acceptable for routine clinical use.

CONCLUSION

Although considerable consensus was achieved, further research is necessary before this technology should be used in routine practice.

Tracers in Gastric Cancer Surgery

The treatment of gastric cancer mainly depends on radical gastrectomy. Determination of appropriate surgical margins and adequate lymph node (LN) resection are two major surgical steps that directly correlate with prognosis in gastric cancer. Due to the expanding use of minimally invasive procedures, it is no longer possible to locate tumors and LNs through touch. As an alternative, tracers have begun to enter the field due to their capacities for intraoperative visualization. Herein, we summarize the application of contemporary tracers in gastric cancer surgery, including isosulfan blue, methylene blue, patent blue, indocyanine green, carbon particles, and radioactive tracers. Their mechanisms, administration methods, detection efficiency, and challenges, as well as perspectives on them, are also outlined.

Stannous colloid mixed with indocyanine green as a tracer for sentinel lymph node navigation surgery

The combined use of a vital dye and radioactive colloid reportedly performs better in detecting sentinel lymph nodes (SLNs) for cancers than the use of either of them alone. However, especially for gastric cancer, two endoscopic procedures are required to administer these two tracers, which burdens the patients and practitioners. Here we propose the use of stannous colloid (SnC) mixed with indocyanine green (ICG) as a new mixed tracer (SnC-ICG); its characteristics were investigated in vivo and in vitro to estimate its usefulness for SLN navigation. The tracers were administered to rats and the accumulation of radioactivity and/or near-infrared fluorescence were evaluated in the regional lymph nodes (LNs) using single positron emission computed tomography and near-infrared fluorescence imaging, respectively. SnC-ICG showed significantly better clearance from the injection site and better migration to primary LNs than the single administration of SnC or ICG aqueous solution. SnC-ICG demonstrated a wide particle size variability, stabilized to 1200-nm upon the addition of albumin in vitro; These properties could contribute to its behavior in vivo. The use of SnC-ICG could contribute better performance to detect SLNs for gastric cancer with less burden on both patients and medical practitioners.

Life prognosis of sentinel node navigation surgery for early-stage gastric cancer: Outcome of lymphatic basin dissection

BACKGROUND

Lymphatic basin dissection is a sentinel node biopsy method that is specific for gastric cancer. In this method, the dyed lymphatic system is dissected en bloc, and sentinel nodes are identified at the back table (ex vivo). Even with lymphatic basin dissection, blood flow to the residual stomach can be preserved, and function-preserving curative gastrectomy can be performed. The oncological safety of function-preserving curative gastrectomy combined with lymphatic basin dissection has not yet been fully investigated. We hypothesized that the oncological safety of sentinel node navigation surgery (SNNS) is not inferior to that of the guidelines.

AIM

To investigate the life prognosis of SNNS for gastric cancer in comparison with guidelines surgery.

METHODS

This was a retrospective cohort study. Patients were selected from gastric cancer patients who underwent sentinel node biopsy from April 1999 to March 2016. Patients from April 1999 to August 2008 were from the Department of Surgery II, Kanazawa University Hospital, and patients from August 2009 to March 2016 were from the Department of Surgical Oncology, Kanazawa Medical University Hospital. Patients who were diagnosed with gastric cancer, which was preoperatively diagnosed as superficial type (type 0), 5 cm or less in length, clinical T1-2 and node negative, and underwent various gastrectomies guided by sentinel node navigation were retrospectively collected. The overall survival (OS) and relapse-free survival (RFS) of these patients (SNNS group) were investigated. Patients with gastric cancer of the same stage and who underwent guidelines gastrectomy with standard nodal dissection were also selected as the control group.

RESULTS

A total of 239 patients in the SNNS group and 423 patients in the control group were included. Pathological nodal metastasis was observed in 10.5% and 10.4% of the SNNS and control groups, respectively. The diagnostic abilities of sentinel node biopsy were 84% and 98.6% for sensitivity and accuracy, respectively. In the SNNS group, 81.6% of patients underwent modified gastrectomy or function-preserving curative gastrectomy with lymphatic basin dissection, in which the extent of nodal dissection was further reduced compared to the guidelines. The OS rate in the SNNS group was 96.8% at 5 years and was significantly better than 91.3% in the control group (P = 0.0014). The RFS rates were equal in both groups. After propensity score matching, there were 231 patients in both groups, and the cumulative recurrence rate was 0.43% at 5 years in the SNNS group and 1.30% in the control group, which was not statistically different.

CONCLUSION

The oncological safety of patients who undergo gastrectomy guided by sentinel node navigation is not inferior to that of the guidelines surgery.

nPTD classification: an updated classification of gastric cancer location for function preserving gastrectomy based on physiological lymphatic flow

Background

The correlation between tumor location and lymphatic flow distribution in gastric cancer has been previously reported, and PTD (Proximal – Transitional – Distal) classification was proposed. Our group updated and developed the nPTD classification.

Method

We retrospectively studied gastric cancer patients who underwent the dye method sentinel node biopsy from 1993 to 2020. The inclusion criteria were a single lesion type 0 cancer of ≤5 cm in the long axis, clinically node-negative, and invasion within the proper muscle layer pathologically. In this study, the distribution of dyed lymphatic flow was evaluated for each occupied area of the tumor.

Results

We included 416 patients in this study. The tumors located in the watershed of the right and left gastroepiploic arteries near greater curvature had extensive lymphatic flow; therefore, a newly circular region with a diameter of 5 cm is set on the watershed of the greater curvature between P and T zone as the ‘n’ zone. In addition, for cancers located in the lesser P curvature, lymphatic flow to the greater curvature was not observed. Therefore, the P zone was divided into two: the lesser curvature side (PL) and the greater curvature side (PG).

Conclusions

The advantage of the nPTD classification is that it provides not only proper nodal dissection but also adequate function-preserving gastrectomy. If the tumor is localized within the PL, the proximal gastrectomy resection area can be further reduced. In contrast, for cancers located in the ‘n’ zone, near-total gastrectomy is required because of the extensive lymphatic flow.

Real-time fluorescence image-guided gastrointestinal oncologic surgery: Towards a new era

Technological improvements are crucial in the evolution of surgery. Real-time fluorescence-guided surgery (FGS) has spread worldwide, mainly because of its usefulness during the intraoperative decision-making processes. The success of any gastrointestinal oncologic resection is based on the anatomical identification of the primary tumor and its regional lymph nodes. FGS allows also to evaluate the blood perfusion at the gastrointestinal stumps after colorectal or esophageal resections. Therefore, a reduction on the anastomotic leak rates has been postulated as one of the foreseeable benefits provided by the use of FGS in these procedures. Although the use of fluorescence in lymph node detection was initially described in breast cancer surgery, the technique is currently applied in gastric or splenic flexure cancers, as they both present complex and variable lymphatic drainages. FGS allows also to perform intraoperative lymphograms or sentinel lymph node biopsies. New applications of FGS are being developed to assist in the detection of peritoneal metastases or in the evaluation of the tumor resection margins. The present review aims to provide a general overview of the current status of real-time FGS in gastrointestinal oncologic surgery. We put a special focus on the different applications of FGS, discussing the main findings and limitations found in the contemporary literature and also the promising near future applications.

Time to maximum indocyanine green fluorescence of gastric sentinel lymph nodes and feasibility of combined indocyanine green/sodium fluorescein gastric lymphography

PURPOSE

Indocyanine green (ICG) and sodium fluorescein (SF) are fluorescent dyes used for sentinel lymph node mapping. In oncological gastric surgery, ICG lymphography has increased the number of resected lymph nodes. However, the optimal time to administer ICG is unclear, and both preoperative and intraoperative injections have been practised. As dye spillage will diminish lymphogram visibility, a second dye with different excitation and emission spectra may present a clinical alternative. We measured the time until maximum ICG fluorescence of gastric sentinel lymph nodes and investigated the feasibility of combined lymphography with two fluorescent dyes: ICG and SF.

METHODS

Ten Danish Landrace/Yorkshire pigs were used in this study. After completion of the laparoscopic setup, ICG and then SF were endoscopically injected into the gastric submucosa. Lymphograms for both dyes were recorded, and the time until maximum ICG sentinel lymph node fluorescence was determined.

RESULTS

The mean time until maximum ICG fluorescence of gastric sentinel lymph nodes was 50 s (± 12.5), and the fluorescent signal then remained stable until the end of the recorded period (45 min). A lymphogram showing both ICG and SF was acquired for eight of the ten pigs.

CONCLUSIONS

Because of the short time until maximum ICG fluorescence of sentinel lymph nodes, intraoperative injections could be a sufficient alternative to preoperative injections for oncological gastric surgery. Combined ICG and SF lymphography was feasible and resulted in clear lymphograms with no interference between the two dyes. The ability to use multiple dyes during a surgical procedure offers the exciting prospect of simultaneously assessing perfusion and performing fluorescence lymphography.

Recent Developments of ICG-Guided Sentinel Lymph Node Mapping in Oral Cancer

Sentinel lymph node (SLN) biopsy has gained attention as a method of minimizing the extent of neck dissection with a similar survival rate as elective neck dissection in oral cancer. Indocyanine green (ICG) imaging is widely used in the field of surgical oncology. Real-time ICG-guided SLN imaging has been widely used in minimally invasive surgeries for various types of cancers. Here, we provide an overview of conventional SLN biopsy and ICG-guided SLN mapping techniques for oral cancer. Although ICG has many strengths, it still has limitations regarding its potential use as an ideal compound for SLN mapping. The development of novel fluorophores and imaging technology is needed for accurate identification of SLNs, which will allow precision surgery that would reduce morbidities and increase patient survival.

How useful is sentinel lymph node biopsy for the status of lymph node metastasis in cT1N0M0 gastric cancer? A systematic review and meta-analysis

Sentinel lymph node biopsy (SLNB) is intriguing because it is expected to further expand the indication of endoscopic resection (ER) for cT1N0M0 gastric cancer and as an additional operation for post-ER gastric cancer. The aim of our study was to perform a systematic review and meta-analysis on the feasibility and diagnostic value of SLNB technique in patients with cT1N0M0 gastric cancer. Eligible studies were systematically searched in PubMed, Embase, and Cochrane Library databases from inception to April 2020. A random-effect model was used to pool the data, and subgroup analysis was used to explain the heterogeneities. A total of 22 clinical studies (1993 patients with cT1N0M0 gastric cancer) were included. The pooled SLN identification rate, sensitivity, specificity, and diagnostic odds ratio with 95% confidence intervals were 0.99 (0.99-1.00), 0.92 (0.88-0.95), 1.00 (1.00-1.00), and 832.8 (395.5-1753.6), respectively. The summary receiver operator characteristic displayed a test accuracy of 99.3%. Subgroup analysis found an improved SLN sensitivity for studies with the mean number of SLNs > 4 and studies stained with a combination of hematoxylin-eosin with immunohistochemistry (HE + IHC). Further, studies using the basin dissection were associated with a higher SLN identification rate. The current meta-analysis provides data that favors the use of SLNB for predicting the status of lymph node metastasis in patients with cT1N0M0 gastric cancer. However, establishing standard procedure and suitable criteria for further application and optimization of SLNB is urgently needed.

Intraoperative fluorescence with indocyanine green in congenital cardiac surgery: Potential applications of a novel technology

Background

Achieving successful repair of congenital heart defects requires attention to detail. Careful evaluation of anastomotic site patency, reimplanted coronary arteries, location of epicardial coronaries, and myocardial perfusion may be necessary to ensure safe conduct of the operation and achieve excellent outcomes.

Methods

Intraoperative fluorescence angiography (IOFA) was performed using indocyanine green in patients undergoing the following procedures: coronary artery reimplantation, coronary artery unroofing, evaluation of intraoperative coronary anatomy, reoperation requiring ventriculotomy, coarctation/interrupted aortic arch repair, systemic-to-pulmonary artery shunt, Norwood procedure, thoracic duct localization, and vascular rings.

Results

The technique was feasible in all patients. No mortality or adverse events related to the dye were encountered. Adequate intraoperative imaging was obtained in 15 patients (20 images), which correlated well with postoperative studies. The imaging quality was superior for assessing shunt patency, myocardial perfusion, and anastomotic patency and determining the location of epicardial coronary arteries but was less so for assessing branch pulmonary arteries.

Conclusions

IOFA is a useful and safe technique that can provide a quick on-table assessment of a variety of congenital surgical procedures. This may help answer questions that can minimize postoperative interventions and help ensure a smooth perioperative course and excellent outcomes.

A Systematic Review and Meta-Analysis of Sentinel Lymph Node Biopsy in Gastric Cancer, an Optimization of Imaging Protocol for Tracer Mapping

BACKGROUND

Sentinel lymph node biopsy (SLNB) plays an essential role in the evaluation of lymph node (LN) metastasis status and the extent of LN dissection in gastric cancer. The aim of our study was to perform a systematic review and meta-analysis for corresponding identification rate and sensitivity of different SLNB techniques.

METHODS

Systematic search using PubMed, Embase, and Cochrane library databases was conducted for studies on SLNB in patients with gastric cancer. Studies were stratified according to the sentinel lymph node (SLN) biopsy technique: blue dye (BD), radiocolloid tracer (RI), indocyanine green (ICG), a combination of radiocolloid with blue dye (RI + BD), and a combination of radiocolloid with ICG (RI + ICG). A random-effect model was used to pool the identification rate, sensitivity, and accuracy.

RESULTS

A total of 54 eligible studies (3767 patients) was included. The pooled identification rates of SLNB using BD, RI, ICG, RI + BD, RI + ICG were 95% (95%CI: 92-97%), 95% (95%CI: 93-97%), 99% (95%CI: 97-99%), 97% (95%CI: 96-98%), and 95% (95%CI: 87-99%), respectively. The pooled sensitivities were 82% (95%CI: 77-86%), 87% (95%CI: 81-92%), 90% (95%CI: 82-95%), 89% (95%CI: 84-93%), and 88% (95%CI: 79-94%), respectively. The pooled accuracies were 94% (95%CI: 91-96%), 95% (95%CI: 92-97%), 98% (95%CI: 95-99%), 97% (95%CI: 95-99%), and 98% (95%CI: 95-99%), respectively.

CONCLUSIONS

The current meta-analysis provides reliable evidence that favors the use of ICG and dual tracer method (RI + BD/ICG) for the identification of the SLN. Considering the high costs and potential biohazard of using radioactive substances in dual tracer method, performing SLNB with ICG is the technique of choice for experienced surgeons.

Recent updates and current issues of sentinel node navigation surgery for early gastric cancer

With the increase in the incidence of early gastric cancer (EGC), several endoscopic and laparoscopic approaches, such as endoscopic submucosal dissection and function-preserving gastrectomy, have been accepted as standard treatments. Sentinel node navigation surgery (SNNS) is an ideal surgical option for preservation of most parts of the stomach and consequent maintenance of normal gastric function to improve quality of life in patients with EGC. Although many previous studies and clinical trials have demonstrated the safety and feasibility of the sentinel node concept in gastric cancer, the clinical application of SNNS is debatable. Several issues regarding technical standardization and oncological safety need to be resolved. Recently several studies to resolve these problems are being actively performed, and SNNS might be an important surgical option in the treatment of gastric cancer in the future.

The Clinical Value of Fluorescent Lymphography with Indocyanine Green During Robotic Surgery for Gastric Cancer: a Matched Cohort Study

BACKGROUND

Near-infrared (NIR) fluorescence imaging with indocyanine green (ICG) has been recently introduced for lymphatic mapping in several tumors. We aimed at investigating whether this technology may improve the intraoperative visualization of lymph nodes during robotic gastrectomy for gastric cancer.

METHODS

Between June 2014 and June 2018, a total of 94 patients underwent robotic gastrectomy with D2 lymph node dissection for gastric cancer. In 37 patients, ICG was injected endoscopically into the submucosal layer around the tumor the day before surgery. After propensity score matching, the results of these 37 patients were compared with the results of 37 control patients who had undergone robotic gastrectomy without ICG injection.

RESULTS

Among the 37 patients within the ICG group, no adverse events related to ICG injection or intraoperative NIR imaging occurred. After completion of D2 lymph node dissection, no residual fluorescent lymph nodes were left in the surgical field. A mean of 19.4 ± 14.7 fluorescent lymph nodes was identified per patient. The mean total number of harvested lymph nodes was significantly higher in the ICG group than in the control group (50.8 vs 40.1, P = 0.03). In the ICG group, 23 patients had metastatic lymph nodes. The accuracy, sensitivity, and specificity of ICG fluorescence for metastatic lymph nodes were 62.2%, 52.6%, and 63.0%, respectively.

CONCLUSION

Our study indicates that NIR imaging with ICG may provide additional node detection during robotic surgery for gastric cancer. Unfortunately, this technique failed to show good selectivity for metastatic lymph nodes.

Severity of postgastrectomy syndrome and quality of life after advanced gastric cancer radical gastrectomy

It has previously been suggested that postgastrectomy syndrome (PGS) is more severe in patients after surgery for advanced gastric cancer than in patients with early gastric cancer. Using the postgastrectomy syndrome assessment scale-45 (PGSAS-45), the present study aimed to determine whether PGS for postgastrectomy patients, in Kanazawa Medical University Hospital, with advanced gastric cancer was more severe than for patients with early gastric cancer. A questionnaire survey was conducted using PGSAS-45 for curative gastric cancer gastrectomy cases at Kanazawa Medical University Hospital. The questionnaire data were combined with patient background data, anonymized and moved to an unlinked file for patient privacy. Using this dataset, non-recurrent cases of distal partial gastrectomy were extracted and divided into two groups, stage IA or IB patients (group E), and stage IIA or higher (group A). The main outcome measures (MOMs) of PGSAS-45 were compared between the two groups. The participants in the present study included 35 cases in group E and 22 cases in group A. The results of a univariate analysis to compare the MOMs between the two groups showed that only the dumping subscale was significantly different in group A and was judged to be caused by the underlying bias of the background factor. There were no MOMs with significant differences in the pathological stage based on multiple regression analyses. In cases of distal partial gastrectomy, the PGS and quality of life (QoL) of patients following advanced gastric cancer surgery were similar to those of patients with early gastric cancer. The standardized treatment for advanced gastric cancer did not induce notable postoperative failures, and QoL was not impaired. In contrast, for early-stage gastric cancer cases, the present study suggests that it is necessary to distinguish metastasis-negative cases to indicate an appropriate, function-preserving curative gastrectomy.

A new method of sentinel node mapping for early gastric cancer using a fluorescent laparoscope that can adjust the intensity of excitation light and quantify the intensity of indocyanine green fluorescence: Report of a case

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VISION SENSE® is a new near-infrared fluorescence laparoscope, and allows adjustment of the intensity of excitation light and quantification of the intensity of ICG fluorescence during observation.

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Using VISION SENSE®, when many ICG-positive lymph nodes are observed, we can select lymph nodes by quantifying ICG fluorescence during surgery.

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This procedure might improve SN mapping for early gastric cancer.

Introduction

One of the drawbacks of indocyanine green (ICG) fluorescence sentinel node (SN) mapping is the impossibility of quantifying lymph node fluorescence during surgery. VISION SENSE® is a new near-infrared fluorescence laparoscope for bright-field full-color observation, and provides the ability to adjust the intensity of excitation light and quantify the intensity of ICG fluorescence during observation.

We report the case of a patient who underwent ICG SN mapping for early gastric cancer using VISION SENSE®.

Presentation of case

A woman in her 60 s was diagnosed with cType0-IIc early gastric cancer located in the anterior wall of the middle gastric body (25 mm in diameter, cT1b, cN0, cM0, cStage IA). Contrast-enhanced computed tomography showed no metastases. Laparoscopy assisted distal gastrectomy with D1+ lymph node dissection and SN mapping with ICG fluorescence using the VISION SENSE® were successfully performed. Using VISION SENSE®, we could select those lymph nodes objectively showing high intensity by quantifying ICG fluorescence during surgery.

The pathological diagnosis was well-differentiated adenocarcinoma, pT1a, N0, M0, pStage IA. No ICG-positive lymph nodes (8 nodes) contained metastases.

Postoperative course was good, with no complications.

Discussion

The use of VISION SENSE® allowing adjustment of excitation light and quantification of ICG fluorescence intensity might decreased the false-negative rate for SNs and increased the sensitivity of the ICG for detecting SNs.

Conclusion

We successfully performed ICG SN mapping for early gastric cancer using VISION SENSE®.

Sentinel node mapping for post-endoscopic resection gastric cancer: multicenter retrospective cohort study in Japan

BACKGROUND

Standard gastrectomy with systematic lymphadenectomy as an additional surgery after endoscopic resection (ER) causes a deterioration in long-term quality of life. If the sentinel lymph node (SN) basin concept can be applied in post-ER gastric cancer, minimal surgery can be applied without reducing the curability. This retrospective multicenter cohort study aimed to verify the validity of the SN basin concept in post-ER gastric cancer.

PATIENTS AND METHODS

Individual data of 132 patients who underwent SN mapping after ER were collected from 8 university hospitals in Japan from 2001 to 2016. Tracers were injected endoscopically in the submucosal layer at four sites around the post-ER scar. We compared the SN basin distribution of post-ER gastric cancer with that of 275 patients with non-ER gastric cancer.

RESULTS

Two cases of SN were unidentified, both involving a single tracer (SN detection rate: 98.5%). Nine cases (6.8%) of lymph node metastasis were found, of which eight had a metastatic lymph node within the SNs and one had a non-SN metastasis within the SN basin. The diagnostic sensitivity of SN mapping for lymph node metastasis was 88.9% in post-ER group and 95.7% in non-ER group (P = 0.490); the accuracy was 99.2% and 99.6% (P = 0.539), respectively. Regarding the SN basin, no significant intergroup differences were found regardless of the primary tumor location.

CONCLUSIONS

Our findings clarified the feasibility of SN mapping based on the SN basin concept in patients with gastric cancer who previously underwent ER.

Real-time near-infrared fluorescence imaging mediated by blue dye in breast cancer patients

BACKGROUND

Near-infrared (NIR) fluorescence imaging has recently been introduced to the sentinel lymph node (SLN) mapping because of the benefits of the SLN biopsy, such as providing real-time and high-resolution optical guidance. Methylene blue is available and less expensive as an SLN mapping tracer. Our study aims to identify SLN through the NIR fluorescence imaging system mediated by blue dye.

METHODS

Early-stage breast cancer patients were prospectively enrolled. All participants received a subareolar or peritumoral injection of 1 mL methylene blue (MB) before surgery. The MB fluorescence system was set immediately after injection. SLNs were searched and removed under the guidance of fluorescence and blue dye.

RESULTS

We identified SLN adequately with the help of real-time lymphography and blue dye. Symbolic lymphatic drainage patterns were also observed.

CONCLUSION

NIR fluorescence imaging mediated by blue dye has benefits on the identification of lymph vessels, the location of SLN, and the patterns of breast lymphatic flow.

Sentinel lymph node detection for gastric cancer: Promise or pitfall?

At present, optimal surgery for gastric cancer is still under debate, especially the extent of lymph node dissection. Gastrectomy with D1/D2 lymphadenectomy is standard treatment for resectable advanced gastric cancer. However, in early gastric cancer without lymph node metastasis, gastrectomy with D1/D2 lymphadenectomy may not be unnecessary, which could increases morbidity and mortality and reduces the quality of life (QOL). Therefore, the concept of sentinel lymph node could be applied in gastric cancer. But due to the complexity of gastric lymphatic drainage, there are still many issues under debate, such as suitable tracers, the method of mapping and collecting and the oncologic safety of sentinel node navigation surgery (SNNS). In addition, skip metastasis and unreliability of intraoperative pathological diagnosis are two main reasons for false negative cases. In this review, we summarize the current status and controversy of sentinel lymph node detection in gastric cancer, attempting to help with practical application. Further, we hold opinion that we should be cautious about performing sentinel lymph node detection in gastric cancer before an accurate and effective method occurs.

[Fluorescence-guided detection of lymph node metastases of gastrointestinal tumors]

A correct lymph node (LN) staging is essential in oncological surgery. Indocyanine green (ICG) near-infrared fluorescence (NIRF) guided sentinel lymph node (SLN) navigation is a relatively novel technique. The aim of this review is to analyze the impact of ICG-NIRF on identification of LN metastases of gastrointestinal tumors. The Scopus and PubMed/MEDLINE literature databases were searched and 20 studies were included. The ICG-NIRF navigation of LN has been shown to enable and improve LN detection in gastrointestinal tumors; however, the mean detection, sensitivity, accuracy and false negative rates show substantial variation. This could be due to both the heterogeneous techniques applied and to the low retention of ICG by lymph nodes. Fluorescence imaging to identify LN drainage is a promising tool to improve oncological outcomes. Nonetheless, the technique requires further development in terms of hardware, software and fluorophores, which are currently being investigated.

Precision surgical approach with lymph-node dissection in early gastric cancer

The gravest prognostic factor in early gastric cancer is lymph-node metastasis, with an incidence of about 10% overall. About two-thirds of early gastric cancer patients can be diagnosed as node-negative prior to treatment based on clinic-pathological data. Thus, the tumor can be resected by endoscopic submucosal dissection. In the remaining third, surgical resection is necessary because of the possibility of nodal metastasis. Nevertheless, almost all patients can be cured by gastrectomy with D1+ lymph-node dissection. Laparoscopic or robotic gastrectomy has become widespread in East Asia because perioperative and oncological safety are similar to open surgery. However, after D1+ gastrectomy, functional symptoms may still result. Physicians must strive to minimize post-gastrectomy symptoms and optimize long-term quality of life after this operation. Depending on the location and size of the primary lesion, preservation of the pylorus or cardia should be considered. In addition, the extent of lymph-node dissection can be individualized, and significant gastric-volume preservation can be achieved if sentinel node biopsy is used to distinguish node-negative patients. Though the surgical treatment for early gastric cancer may be less radical than in the past, the operative method itself seems to be still in transition.

The Feasibility and Safety of Preoperative Fluorescence Marking with Indocyanine Green (ICG) in Laparoscopic Gastrectomy for Gastric Cancer

BACKGROUND

Securing the surgical margin is the most essential and important task in curative surgery. However, it is difficult to accurately identify the tumor location during laparoscopic surgery for gastric cancer, and existing methods, such as preoperative endoscopic marking with tattooing and clipping, have multiple disadvantages.

AIMS

We investigated the feasibility and safety of indocyanine green (ICG) fluorescence marking for determining the tumor location during laparoscopic gastrectomy.

METHODS

We retrospectively analyzed preoperative and perioperative data from consecutive patients with gastric cancer undergoing planned laparoscopic distal gastrectomy. Data was maintained in a prospectively compiled surgical database, and patients were categorized into ICG (n = 84) or non-ICG (n = 174) groups based on whether they underwent preoperative endoscopic mucosal ICG injection. One-to-one propensity score matching (PSM) was performed to compare outcomes between the two groups.

RESULTS

We included 84 patient pairs after PSM, and there were no significant differences in preoperative patient characteristics. The ICG group had shorter procedure time (p < 0.001), lower estimated blood loss (p = 0.005), and significantly shorter postoperative hospital stay (p < 0.001). Positive resection margins were confirmed in five cases (6.0%) in the non-ICG group, whereas there were none in the ICG group (p = 0.008). Real-time confirmation was possible during laparoscopy, and the injected ICG did not affect the surgical procedure or result in adverse events.

CONCLUSION

ICG fluorescence imaging is feasible and safe and can potentially be used as a tumor-marking agent for determining the surgical resection line.

Sentinel lymph node mapping by near-infrared fluorescence imaging and contrast-enhanced ultrasound in healthy dogs

Sentinel lymph node (SLN) mapping is a valuable and crucial diagnostic procedure in staging malignancies. We compared two non-invasive techniques, near-infrared (NIR) fluorescence imaging and contrast-enhanced ultrasound (CEUS), to identify the SLNs in three superficial anatomical regions in an animal model. Six healthy laboratory dogs were included in a proof-of-concept trial. A NIR fluorescent dye (Indocyanine Green) and microbubbles (Sonovue) were consecutively injected subdermally in the Inguinal, axillary and popliteal region to map the SLNs. Transcutaneous NIR fluorescence imaging identified SLNs in 17 out of a total of 18 occasions. CEUS identified SLNs in all regions (18/18). Whereas NIR fluorescence imaging performed better in the visualization of the afferent lymphatic tract, CEUS demonstrated different filling patterns of the SLNs, a feature potentially critical for the concept of SLN mapping in cancer patients. Both NIR fluorescence imaging and CEUS are safe, non-invasive, practical and accurate methods to perform real-time transcutaneous SLN mapping with potential in a clinical setting.

Fluorescent-guided surgery for sentinel lymph node detection in gastric cancer and carcinoembryonic antigen targeted fluorescent-guided surgery in colorectal and pancreatic cancer

Sentinel lymph node procedures for gastric cancer resections using indocyanine green (ICG) linked to Nanocoll outperformed normal ICG but did not provide information on possible lymph node metastasis. Carcinoembryonic antigen targeted fluorescent imaging using SGM‐101 was successful in both pancreatic and colorectal cancer. A large phase III multicentre trial will soon be initiated in colorectal cancer patients.

Indocyanine green-based fluorescence imaging in visceral and hepatobiliary and pancreatic surgery: State of the art and future directions

In recent years, the use of fluorescence-guided surgery (FGS) to treat benign and malignant visceral, hepatobiliary and pancreatic neoplasms has significantly increased. FGS relies on the fluorescence signal emitted by injected substances (fluorophores) after being illuminated by ad hoc laser sources to help guide the surgical procedure and provide the surgeon with real-time visualization of the fluorescent structures of interest that would be otherwise invisible. This review surveys and discusses the most common and emerging clinical applications of indocyanine green (ICG)-based fluorescence in visceral, hepatobiliary and pancreatic surgery. The analysis, findings, and discussion presented here rely on the authors' significant experience with this technique in their medical institutions, an up-to-date review of the most relevant articles published on this topic between 2014 and 2018, and lengthy discussions with key opinion leaders in the field during recent conferences and congresses. For each application, the benefits and limitations of this technique, as well as applicable future directions, are described. The imaging of fluorescence emitted by ICG is a simple, fast, relatively inexpensive, and harmless tool with numerous different applications in surgery for both neoplasms and benign pathologies of the visceral and hepatobiliary systems. The ever-increasing availability of visual systems that can utilize this tool will transform some of these applications into the standard of care in the near future. Further studies are needed to evaluate the strengths and weaknesses of each application of ICG-based fluorescence imaging in abdominal surgery.

A practical guide for the use of indocyanine green and methylene blue in fluorescence-guided abdominal surgery

Near-infrared (NIR) fluorescence imaging is gaining clinical acceptance over the last years and has been used for detection of lymph nodes, several tumor types, vital structures and tissue perfusion. This review focuses on NIR fluorescence imaging with indocyanine green and methylene blue for different clinical applications in abdominal surgery with an emphasis on oncology, based on a systematic literature search. Furthermore, practical information on doses, injection times, and intraoperative use are provided.

Diagnostic evaluation of sentinel lymph node biopsy using indocyanine green and infrared or fluorescent imaging in gastric cancer: a systematic review and meta-analysis

BACKGROUND

Sentinel node navigation surgery (SNNS) for gastric cancer using infrared visualization of indocyanine green (ICG) is intriguing because it may limit operative morbidity. We are the first to systematically review and perform meta-analysis on the diagnostic utility of ICG and infrared electronic endoscopy (IREE) or near infrared fluorescent imaging (NIFI) for SNNS exclusively in gastric cancer.

METHODS

A search of electronic databases MEDLINE, EMBASE, SCOPUS, Web of Science, and the Cochrane Library using search terms "gastric/stomach" AND "tumor/carcinoma/cancer/neoplasm/adenocarcinoma/malignancy" AND "indocyanine green" was completed in May 2017. Articles were selected by two independent reviewers based on the following major inclusion criteria: (1) diagnostic accuracy study design; (2) indocyanine green was injected at tumor site; (3) IREE or NIFI was used for intraoperative visualization. 327 titles or abstracts were screened. The quality of included studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2.

RESULTS

Ten full text studies were selected. 643 patients were identified with the majority of patients possessing T1 tumors (79.8%). Pooled identification rate, diagnostic odds ratio, sensitivity, and specificity were 0.99 (0.97-1.0), 380.0 (68.71-2101), 0.87 (0.80-0.93), and 1.00 (0.99-1.00), respectively. The summary receiver operator characteristic for ICG + IREE/NIFI demonstrated a test accuracy of 98.3%. Subgroup analysis found improved test performance for studies with low-risk QUADAS-2 scores, studies published after 2010 and submucosal ICG injection. IREE had improved diagnostic odds ratio, sensitivity, and identification rate compared to NIFI. Heterogeneity among studies ranged from low (I² < 25%) to high (I² > 75%).

CONCLUSIONS

We found encouraging results regarding the accuracy, diagnostic odds ratio, and specificity of the test. The sensitivity was not optimal but may be improved by a strict protocol to augment the technique. Given the number and heterogeneity of studies, our results must be viewed with caution.

New method of indocyanine green fluorescence sentinel node mapping for early gastric cancer

BACKGROUND

The present study describes the retrospective feasibility study of ICG fluorescence SN mapping in back-table for early gastric cancer using PINPOINT®.

METHOD

SN mapping were performed as following; the day before surgery, 0.5 ml ICG was injected endoscopically in four quadrants of the submucosa surrounding the gastric cancer using an endoscopic puncture. Intraoperatively, the gastrocolic ligament was divided to visualize all possible directions of lymphatic flow from the stomach. PINPOINT® (NOVADAQ, Canada) was used to illuminate regional lymph nodes from the serosal side. Positive staining was confirmed by at least 3 surgeons and an endoscopist during surgery (Figure 1). Lymph node dissection and gastrectomy were performed according to the criteria of gastric cancer treatment guidelines of JGCA.

RESULT

All 6 patients had gastrectomy with laparoscopic approach. ICG positive lymphatic flow and lymph nodes were able to be observed in all the patients. Final pathological diagnosis was all StageI and curative resection. All the patients had ICG positive lymphatic area in left gastric artery (LGA) area. Two patients with tumor located in L area had ICG positive flow to right gastroepipoloic artery (RGEA) area. The mean of ICG positive lymph nodes was 8.6. One patient had a metastatic lymph node in station No.4, which was positive for ICG.

CONCLUSION

Our method made identification of ICG positive lymph nodes easy in SN mapping in back-table under room light. Although further accumulation and analysis are necessary, we may be able to apply this method for intraoperative SN mapping of laparoscopic gastric cancer surgey.

Feasibility and diagnostic performance of dual-tracer-guided sentinel lymph node biopsy in cT1-2N0M0 gastric cancer: a systematic review and meta-analysis of diagnostic studies

BACKGROUND

Dual-tracer-guided sentinel lymph node (SLN) biopsy may provide a promising diagnostic tool to assess accurately the status of lymph node metastasis in the surgical operation and assure the oncologic safety of the function or stomach preserving surgery. The diagnostic performance of this technology in recent studies varied. Thus, we conducted this meta-analysis.

METHODS

This systematic review and meta-analysis was registered at the PROSPERO. Eligible studies were searched in the PubMed, EMBASE, Web of Knowledge, and Cochrane Library databases. A random-effect model was used to pool the data. Summary receiver operator characteristic curves, analysis for publication bias, meta-regression, and subgroup analysis were also performed.

RESULTS

The pooled SLN identification rate and sensitivity were 0.97 and 0.89. ^99mTc-human serum albumin with indocyanine green (ICG), ^99mTc-antimony sulfur colloid with ICG, performing SLN biopsy ≥15 min after dye injection, an SLN ≥5, the basin dissection, laparoscopic surgery, in studies conducted in Japan and studies published after 2012, were associated with higher sensitivity. CT1 stage, performing SLN biopsy ≥15 min after dye injection, in studies conducted in Japan and studies published after 2012, were related with a higher identification rate.

CONCLUSIONS

Dual tracer is promising in SLN biopsy in gastric cancer, and the clinical application of SLN biopsy should be limited to the patients of cT1N0M0 gastric cancer. The combination of ^99mTc-human serum albumin and ICG as well as the combination of ^99mTc-antimony sulfur colloid and ICG may be the optimal tracer combination. However, it seems not justified to put this technique into routine clinical application recently. Some factors that might enhance diagnostic value are identified.

Laparoscopic sentinel node navigation surgery for early gastric cancer

Currently, the most accurate method for identifying lymph node metastasis is intraoperative diagnosis by sentinel node (SN) biopsy. Based on the SNNS study-a recent large-scale, nationwide, multicenter prospective study-the SN concept seems to be scientifically valid in patients with early gastric cancer. SN biopsy is a multistep technique consisted of six essential elements: indication, the selection of a tracer, a proper tracer injection method, the objective detection of SNs, a reliable biopsy technique, and the precise detection of nodal metastasis. For SN biopsy of gastric cancer, these elements have been validated as follows: the indication should be limited to clinical T1 less than 4 cm in diameter; combination mapping with radioactive colloid and blue dye is used as the standard; and endoscopic submucosal injection is the standard tracer injection. Detection of SNs and a reliable biopsy technique are enabled by adaptation of lymphatic basin dissection, a proper biopsy technique for gastric cancer. Lymphatic basin dissection is a selective lymphadenectomy procedure for dissecting basins en bloc, collecting lymph nodes and lymphatic vessels stained with dye. Lymphatic basin dissection is superior to the ordinary pick-up method, not only for minimizing the rate of missed SNs, but also in terms of oncological safety as it complements an intraoperative frozen section diagnosis by serving as a backup dissection. Moreover, indocyanine green (ICG) fluorescence mapping has been developed in recent years. ICG fluorescence mapping is superior because of its high sensitivity and signal stability. Moreover, it is feasible for both open and laparoscopic gastrectomy in treating early gastric cancer. SN biopsy has brought dramatic changes to laparoscopic surgery for early gastric cancer. With laparoscopic SN biopsy using ICG fluorescence navigation, laparoscopic surgery for early gastric cancer has changed from the uniform standard gastrectomy with D1+ into a tailor-made function-preserving surgical procedure, such as local resection with lymphatic basin dissection.

Current status and challenges in sentinel node navigation surgery for early gastric cancer

Although a number of feasibility studies for sentinel node (SN) concepts in gastric cancer have been conducted since 2000, there remains a debate regarding detailed detection techniques and oncological safety. Two important multicenter phase II clinical trials were performed in Japan that used different methods and reached different conclusions; one confirmed acceptable results with a false-negative rate of 7%, and the other showed an unacceptably high false-negative rate of 46.4%. The Sentinel Node Oriented Tailored Approach (SENORITA) trial is a multicenter randomized controlled phase III trial being performed in Korea. Patient enrollment is now complete and the long-term results are currently awaited. Recently, an image-guided SN mapping technique using infrared ray/fluorescence was introduced. This method might be a promising technology because it allows the clear visualization of SNs. With regard to the primary tumor, the non-exposed endoscopic wall-inversion surgery technique and non-exposure endolaparoscopic full-thickness resection with simple suturing technique have been reported. These methods prevent abdominal infection and tumor seeding and can be good alternatives to conventional laparoscopic gastric wedge resection. For indications, SN navigation surgery can be extended to patients who underwent non-curative endoscopic resection. Although a few studies have been performed on these patients, sentinel concepts may be beneficial to patients as they omit the need for additional gastrectomy. SN navigation surgery can lead to actual organ-preserving surgery and plays a key role in improving the quality of life of patients with early gastric cancer in the future.

Local resection of the stomach for gastric cancer

The local resection of the stomach is an ideal method for preventing postoperative symptoms. There are various procedures for performing local resection, such as the laparoscopic lesion lifting method, non-touch lesion lifting method, endoscopic full-thickness resection, and laparoscopic endoscopic cooperative surgery. After the invention and widespread use of endoscopic submucosal dissection, local resection has become outdated as a curative surgical technique for gastric cancer. Nevertheless, local resection of the stomach in the treatment of gastric cancer in now expected to make a comeback with the clinical use of sentinel node navigation surgery. However, there are many issues associated with local resection for gastric cancer, other than the normal indications. These include gastric deformation, functional impairment, ensuring a safe surgical margin, the possibility of inducing peritoneal dissemination, and the associated increase in the risk of metachronous gastric cancer. In view of these issues, there is a tendency to regard local resection as an investigative treatment, to be applied only in carefully selected cases. The ideal model for local resection of the stomach for gastric cancer would be a combination of endoscopic full-thickness resection of the stomach using an ESD device and hand sutured closure using a laparoscope or a surgical robot, for achieving both oncological safety and preserved functions.