History and evidence for state of the art of lymphadenectomy in esophageal cancer surgery

The current curative multimodal treatment of advanced esophageal cancers consists of neoadjuvant or perioperative chemo(radio)therapy followed by a radical surgical resection of the primary tumor and a 2- or 3-field lymphadenectomy. One of the most important predictors of long-term survival of esophageal cancer patients is lymph node involvement. The distribution pattern of lymph node metastases in esophageal cancer is unpredictable and depends on the primary tumor location, histology, T-stage and application of neoadjuvant or perioperative treatment. The optimal extent of the lymphadenectomy remains controversial; there is no global consensus on this topic yet. Some surgeons advocate an aggressive and extended lymph node dissection to remove occult metastatic disease, to optimize oncological outcomes. Others promote a more restricted lymphadenectomy, since the benefit of an extended lymphadenectomy, especially after neoadjuvant chemoradiotherapy, has not been clearly demonstrated, and morbidity may be reduced. In this review, we describe the development of lymphadenectomy, followed by a summary of current evidence for lymphadenectomy in esophageal cancer treatment.

Comparison of indocyanine green-near-infrared fluorescence guided and traditional mediastinal lymphadenectomy during radical esophagectomy: A randomized controlled trial

BACKGROUND

The extent of lymph node dissection during radical esophagectomy remains a controversial topic. Thus, this study mainly aimed to explore the location of sentinel lymph nodes in esophageal squamous cell carcinoma and the application value of the indocyanine green-near-infrared fluorescence system in lymphadenectomy.

METHODS

This randomized controlled clinical trial (ClinicalTrials.gov, NCT04615806) included 42 participants without neoadjuvant therapy who were lymph node negative based on positron emission tomography/computed tomography findings. Traditional esophagectomy with indocyanine green-near-infrared fluorescence imaging was performed after injecting 0.5 mL indocyanine green (1.25 mg/mL) into the esophageal submucosa in the 4 peritumoral quadrants. The primary endpoint was to determine the location of the sentinel lymph node in esophageal squamous cell carcinoma based on postoperative pathologic reports.

RESULTS

A total of 40 patients, with 20 in each group, were included in the final analysis. In the indocyanine green group, indocyanine green-near-infrared fluorescence imaging was successful in all subjects. Seven cases (cases 2, 3, 9, 11, 17, 18, and 20) in the indocyanine green group exhibited lymph node metastases, all of which were near-infrared positive. The detection rate, positive predictive value, negative predictive value, sensitivity, and specificity were 100% (20 of 20 cases), 8.7% (13/150), 100% (265/265), 100% (13/13), and 65.9% (265/402), respectively. All near-infrared-negative lymph nodes were nonmetastatic lymph nodes. In addition, the number of mediastinal lymph nodes resected in the indocyanine green group was significantly higher than in the non-indocyanine green group.

CONCLUSION

Indocyanine green-near-infrared might be an important and promising technique in predicting sentinel lymph nodes of esophageal squamous cell carcinoma and could significantly improve the detection rate of lymph nodes of esophageal squamous cell carcinoma.

Lymphatic flow mapping using near-infrared fluorescence imaging with indocyanine green helps to predict lymph node metastasis intraoperatively in patients with esophageal or esophagogastric junction cancer not treated with neoadjuvant chemotherapy

BACKGROUND

Lymphatic flow mapping using near-infrared fluorescence (NIR) imaging with indocyanine green (ICG) has been used for the intraoperative prediction of lymph node metastasis in esophageal or esophagogastric junction cancer. However, a consistent method that yields sufficient diagnostic quality is yet to be confirmed. This study explored the diagnostic utility of our newly established lymphatic flow mapping protocol for predicting lymph node metastasis in patients with esophageal or esophagogastric junction cancer.

METHODS

We injected 0.5 mL of ICG (500 μg/mL) into the submucosal layer at four peritumoral points on the day before surgery for 54 patients. We performed lymphatic flow mapping intraoperatively using NIR imaging. After determining the NIR status and presence of metastases, evaluable lymph node stations on in vivo imaging and all resected lymph nodes were divided into four categories: ICG+meta+ (true positive), ICG+meta- (false positive), ICG-meta+ (false negative), and ICG-meta- (true negative).

RESULTS

The distribution of ICG+ and meta+ lymph node stations differed according to the primary tumor site. Sensitivity and specificity for predicting meta+ lymph nodes among ICG+ ones were 50% (95% CI 41-59%) and 75% (73-76%), respectively. Predicting meta+ lymph node stations among ICG+ stations improved these values to 66% (54-77%) and 77% (74-79%), respectively. Undergoing neoadjuvant chemotherapy was an independent risk factor for having meta+ lymph nodes with false-negative diagnoses (odds ratio 4.82; 95% CI 1.28-18.19). The sensitivity of our technique for predicting meta+ lymph nodes and meta+ lymph node stations in patients who did not undergo neoadjuvant chemotherapy was 79% (63-90%) and 83% (61-94%), respectively.

CONCLUSION

Our protocol potentially helps to predict lymph node metastasis intraoperatively in patients with esophageal or esophagogastric junction cancer undergoing esophagectomy who did not undergo neoadjuvant chemotherapy.

Standard Lymphadenectomy for Esophageal and Lung Cancer: Variability in the Number of Examined Lymph Nodes Among Pathologists and Its Survival Implication

AIM

We compared variability in number of examined lymph nodes between pathologists and analyzed survival implications in lung and esophageal cancer after standardized lymphadenectomy.

METHODS

Outcomes of 294 N2 dissected lung cancer patients and 132 2-field dissected esophageal cancer patients were retrospectively examined. The primary outcome was difference in reported lymph node count among pathologists. Secondary outcomes were overall and disease-specific survival related to this count and survival related to the 50% probability cut-off value of detecting metastasis based on the number of examined lymph nodes.

RESULTS

The median number of examined lymph nodes in lung cancer was 13 (IQR 9-17) and in esophageal cancer it was 22 (18-29). The pathologist with the highest median number of examined nodes had > 50% higher lymph node yield compared with the pathologist with the lowest median number of nodes in lung (15 vs. 9.5, p = 0.003), and esophageal cancer (28 vs. 17, p = 0.003). Survival in patients stratified by median reported lymph node count in both lung (adjusted RMST ratio < 14 vs. ≥ 14 lymph nodes 0.99, 95% CI 0.88-1.10; p = 0.810) and esophageal cancer (adjusted RMST ratio < 25 vs. ≥ 25 lymph nodes 0.95, 95% CI 0.79-1.15, p = 0.612) was similar. The cut-off value for 50% probability of detecting metastasis by number of examined lymph nodes in lung cancer was 15.7 and in esophageal cancer 21.8. When stratified by this cut-off, no survival differences were seen.

CONCLUSION

The quality of lymphadenectomy based on lymph node yield is susceptible to error due to detected variability between pathologists in the number of examined lymph nodes. This variability in yield did not have any survival effect after standardized lymphadenectomy.

Application of Indocyanine Green Enhanced Fluorescence in Esophageal Surgery: A Mini Review

Despite recent technological innovations and the development of minimally invasive surgery, esophagectomy remains an operation burdened with severe postoperative complications. Fluorescence imaging, particularly using indocyanine green (ICG), offers the ability to address a number of issues faced during esophagectomy. The three main indications for the intraoperative use of ICG during esophagectomy are visualization of conduit vascular supply, allow identification of sentinel nodes and visualization of the thoracic duct. The purpose of this mini review is to present an overview of current practice in fluorescence imaging utilizing ICG during esophagectomy, as well as to demonstrate how this technology can guide lymphadenectomy and reduce surgical morbidity such as anastomotic leaking and chylothorax.

Near-Infrared Fluorescence Image-Guided Surgery in Esophageal and Gastric Cancer Operations

Background

Near-infrared fluorescence image-guided surgery helps surgeons to see beyond the classical eye vision. Over the last few years, we have witnessed a revolution which has begun in the field of image-guided surgery.

Purpose, and Research design

Fluorescence technology using indocyanine green (ICG) has shown promising results in many organs, and in this review article, we wanted to discuss the 6 main domains where fluorescence image-guided surgery is currently used for esophageal and gastric cancer surgery.

Study sample and data collection

Visualization of lymphatic vessels, tumor localization, fluorescence angiography for anastomotic evaluation, thoracic duct visualization, tracheal blood flow analysis, and sentinel node biopsy are discussed.

Conclusions

It seems that this technology has already found its place in surgery. However, new possibilities and research avenues in this area will probably make it even more important in the near future.

Minimally invasive esophagectomy learning curves with different types of background experience

Background

Minimally invasive esophagectomy (MIE) is a complex procedure with learning associated morbidity. The aim was to evaluate the learning curve for MIE focusing on short-term outcomes in two settings: (I) experienced MIE surgeon in new hospital (Hospital 1); (II) surgeons experienced with open esophagectomy and minimally invasive surrogate surgery (Hospital 2).

Methods

In Hospital 1 and Hospital 2, on intent-to-treat basis number of MIEs were 132 and 57, respectively. The primary outcomes were major complications and anastomosis leaks. Secondary outcomes were operative time, blood loss, lymph node yield, hospital stay and 1-year mortality. Length of learning curves were analyzed with risk-adjusted cumulative sum (RA-CUSUM) method.

Results

In Hospital 1, major complication and anastomosis leak rates were 9.8% and 4.5%, 22.8% and 12.3% in Hospital 2, respectively. In Hospital 1, complication and leak rates remained stable. In Hospital 2, improvement occurred after 34 cases in major complications and 29 cases in leaks. Of secondary outcomes, improvements were seen in Hospital 1 in operative time after 61, blood loss after 86, lymph node yield after 52, hospital stay after 19 and 1-year mortality after 24 cases. In Hospital 2, improvement occurred in operative time after 30, blood loss after 15, lymph node yield after 45, hospital stay after 50 and 1-year mortality after 15 cases.

Conclusions

According to this study, learning phase of the individual surgeon determines the outcomes of MIE, not the institutional learning phase.

Exercise capacity in the stair-climbing test predicts outcomes of operable esophageal cancer in minimally invasive era

INTRODUCTION

The risk of complications after esophagectomy highlights the need for careful preoperative assessment. Aim was to assess whether stair-climbing test (SCT) could predict outcomes of patients with operable esophageal cancer in minimally invasive era.

MATERIALS AND METHODS

Patients with esophageal cancer were evaluated for surgical treatment in Central Finland Central Hospital from 2012 to March 2021. Of evaluated 162 patients, 138 were scheduled to eventually undergo surgery. The exercise capacity was evaluated with symptom limited SCT. Patients were divided into four study groups on intent-to-treat basis: surgery and the SCT >14 m (Group 1), surgery and the SCT <11 m (Group 2), non-surgical therapy and the SCT <11 m (Group 3) and non-surgical therapy and the SCT >14 m (Group 4). Results were adjusted for confounders.

RESULTS

Major complication rate was 10.1% vs 40.0% between Group 1 and 2 (p = 0.006), and 90-day mortality 0% vs 20.0% (p < 0.001). Overall survival rates in Groups 1-4 at 1-year were 92.3% vs 72.2% vs 46.8% vs 81.8%, at 3-year 68.5% vs 52.7% vs 15.6% vs 27.3% and at 5-year 58.7% vs 39.5% vs 0% vs 0%, respectively (p < 0.001). In adjusted analysis when compared to Group 1, other groups had increased 5-year mortality hazard (Group 2 HR 2.88 (95% CI 1.25-6.63), Group 3 HR 15.6 (95% CI 5.57-43.5) and Group 4 HR 5.35 (95% CI 2.08-13.7)).

CONCLUSION

Exercise capacity measured with SCT in esophageal cancer patients is a strong predictor of complications and survival, and is a potential parameter to be included in any risk or prognostic models.

Upper mediastinal lymph node dissection based on mesenteric excision in esophageal cancer surgery: confirmation by near-infrared image-guided lymphatic mapping and the impact on locoregional control

BACKGROUND

We previously reported a novel method of mesenteric excision for esophageal cancer surgery. The esophagus, trachea, recurrent laryngeal nerves (RLNs), and surrounding lymph nodes (LNs) are contained in a common mesenterium, which we termed the "mesotracheoesophagus". In addition, near-infrared (NIR) image-guided lymphatic mapping has recently been used. The purpose of this study was to confirm the feasibility of NIR image-guided lymphatic mapping for upper mediastinal LN dissection, and to confirm the oncological feasibility of our surgical approach.

METHODS

Fifteen patients with resectable esophageal cancer underwent submucosal injection of indocyanine green (ICG), and underwent robot-assisted esophagectomy. The frequency of ICG positivity in the LN basins along the RLNs, and metastatic frequency were assessed. Regarding the oncological feasibility of our thoracoscopic esophagectomy, the recurrence patterns and survival of 72 consecutive patients who underwent curative resection from 2011 to 2016 were analyzed.

RESULTS

ICG-positive LN basins along the right and left RLNs were found in 12 (80% of 15) patients (3 patients positive for metastatic LNs) and 11 (73% of 15) patients (2 positive for metastatic LNs and 1 false-negative), respectively. All ICG-positive LN basins were found within the mesotracheoesophagus. The sensitivity was 5/6 (83%), and the negative predictive value was 6/7 (86%). Among the 72 patients, with a median follow-up period of 1644 days, only 3 (4.2%) patients developed locoregional recurrence.

CONCLUSIONS

The NIR image-guided lymphatic mapping was feasible. Our results with no ICG-positive basins outside of the '"mesotracheoesophagus", supported our surgical approach. It might become standard, with acceptable locoregional control.

Performance of Indocyanine-Green Imaging for Sentinel Lymph Node Mapping and Lymph Node Metastasis in Esophageal Cancer: Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVES

Lymphatic mapping with indocyanine-green (ICG) and near-infrared light fluorescent imaging is widely used for sentinel lymph node staging in different types of cancer but is not fully accepted for all procedures because studies have reported heterogeneous results. This study aimed to assess the detection rate (DR) of ICG imaging for sentinel lymph node mapping (SLNM) and lymph node metastases (LNMs) in esophageal cancer.

METHODS

A systematic search was performed to identify relevant studies examining the use of ICG imaging for SLNM in patients with esophageal cancer. Extracted results were pooled in a single-proportion meta-analysis, with a random-effects model, presented as forest plots.

RESULTS

Six studies were included in the analysis. The ICG DR for SLNM was 89% [95% confidence interval (CI) 71%-96%]. The pooled sensitivity and specificity values for the detection of LNMs were 84% (95% CI 64%-94%) and 15% (95% CI 3%-45%), respectively. A trend towards a lower DR was found with increasing mean latency time between ICG injection and SLNM.

CONCLUSIONS

ICG imaging is a technique that potentially could improve lymph node yield excision and, as a consequence, improve the detection of lymph node metastases.

State of the art in esophagectomy: robotic assistance in the abdominal phase

Over the years, robot-assisted esophagectomy gained popularity. The current literature focused mainly on robotic assistance in the thoracic phase, whereas the implementation of robotic assistance in the abdominal phase is lagging behind. Advantages of adding a robotic system to the abdominal phase include robotic stapling and the increased surgeon's independency. In terms of short-term outcomes and lymphadenectomy, robotic assistance is at least equal to laparoscopy. Yet high quality evidence to conclude on this topic remains scarce. This review focuses on the evidence of robotic assistance in the abdominal phase of esophagectomy.

Near-Infrared Fluorescent Image-Guided Lymphatic Mapping in Esophageal Squamous Cell Carcinoma

BACKGROUND

Recently, the feasibility of near-infrared (NIR) image-guided sentinel lymph node (SLN) mapping has been tested in patients with gastrointestinal cancer. The aim of this study is to investigate whether SLN mapping can be used to identify mediastinal lymph node metastases during minimally invasive esophagectomy and explore the lymphatic drainage pattern of esophageal squamous cell carcinoma (ESCC) using NIR fluorescent imaging.

PATIENTS AND METHODS

A total of 21 patients diagnosed with cT1-3 stage ESCC were enrolled. Patients received submucosal injection of indocyanine green diluted with sodium chloride (0.9%) at the start of the esophagectomy procedure followed by NIR mapping.

RESULTS

Thoracoscopic-assisted McKeown esophagectomy with NIR imaging was successfully performed in all patients. The detection rate and number of NIR+ lymph nodes were 95.2% (20/21) and 4.0 (2.0-6.5), respectively. The accuracy, false-negative rates, and negative predictive value were 100% (10 of 10 cases), 0% (0 of 4), and 100% (6 of 6), respectively, for pT1/T2 diseases; and 80.0% (8 of 10), 40% (2 of 5), and 71.4% (5 of 7), respectively, for pT3 diseases. The NIR+ region was the most commonly detected in the right recurrent laryngeal nerve (80%), and the NIR+ region was identified in the upper mediastinal zone in 20 patients.

CONCLUSIONS

Evaluation of the lymphatic drainage pattern and the application of sentinel lymph node in ESCC with real-time NIR imaging could be effective, especially in pT1/2 disease. NIR imaging-guided SLN navigation appears to be a clinically beneficial less-invasive method for treating ESCC.

Transhiatal laparoscopic esophagectomy with extended lymphadenectomy guided by green-indocyanine imaging for adenocarcinoma of the esophagogastric junction

INTRODUCTION

Surgical treatment for adenocarcinoma of the esophagogastric junction (AEGJ) has been long-established, from resection margins to the extension of lymphadenectomy [1,2,4]. The addition of cyanine dye, namely indocyanine green (ICG), to identify suspicious lymph nodes (LN) and evaluate organ vascularization may improve results and outcomes [3].

VIDEO

A 58-year-old female patient with Siewert type II AEGJ was administered mFLOX neoadjuvant treatment. After three cycles, she underwent surgical treatment. The day before surgery, an upper endoscopy was performed to inject 0.2 ml ICG 0.5 cm from the proximal and distal tumor margins. The patient underwent laparoscopic transhiatal esophagectomy with extended lymphadenectomy due to a 4 cm distal esophagus compromised margin. We describe the primary steps of the procedure and demonstrate the role of the ICG in the lymphadenectomy.

RESULTS

Surgery was carried out laparoscopically with a cervical approach (McKeown access), and posterior mediastinal gastric tube reconstruction and cervical gastroplasty were performed. During the standard lymphadenectomy, we observed an ICG-positive LN in station 10, which was found positive in the subsequent pathology examination. After these findings, we performed an extended lymphadenectomy through the splenic hilum. The final pathologic assessment was T3N2 (two perigastric and one positive LN at station 10 among 60 retrieved LN). The operative time was 360 min. The patient started a liquid diet on the seventh postoperative day, and she was discharged on the tenth postoperative day.

CONCLUSIONS

ICG may be helpful to guide both extended lymphadenectomy and distal margin evaluation in transhiatal laparoscopic esophagectomy.

Recent fluorescence imaging technology applications of indocyanine green in general thoracic surgery

Thoracic surgeons perform a wide variety of cancer operations, which are often associated with high morbidity and mortality. Thus, thoracic surgery involves many special challenges that require innovative solutions. The increased utilization of minimally invasive practices, poor overall cancer survival, and significant morbidity of critical operations remain key obstacles to overcome. Fluorescence imaging technology (FIT), involving the implementation of fluorescent dyes and imaging systems, is currently used as an adjunct for general thoracic surgery in many situations and includes sentinel lymph node mapping, pulmonary intersegmental plane identification, pulmonary nodule identification, pulmonary bullous lesion detection, evaluation of the anastomotic perfusion after tracheal surgery, and thoracic duct imaging for postoperative chylothorax. This technology enhances the surgeon's ability to perform operations, and has specific advantages. We review some of the key studies that demonstrate the applications of FIT in the field of general thoracic surgery, focusing on the use of indocyanine green.

Can We Increase the Resection Rate by Minimally Invasive Approach? Experience from 100 Minimally Invasive Esophagectomies

Background

Whether we can increase the resection rate of esophageal cancer by minimally invasive esophagectomy (MIE) is unknown. The aim was to report the number and results of MIE in high-risk patients considered unsuitable for open surgery and compare these results to other operated patients and to high-risk patients not undergoing surgery.

Methods

At Central Finland Central Hospital, between September 2012 and July 2018, the number of operated MIEs was 100. Of these, 10 patients were prospectively considered unfit for open approach. Nineteen additional high-risk patients with operable disease were ruled out of surgery. The short- and long-term outcomes of these 3 groups were compared.

Results

In patients eligible for any approach (n=90), MIE only (n=10), and no surgery (n=19), WHO performance status Grade 0 was observed in 66.7%, 20.0%, and 5.3%, respectively; stair climbing with ≥4 stairs was successfully completed in 77.8%, 50%, and 36.8%, respectively. Between any approach and MIE only groups, rate of major complications (Clavien-Dindo ≥3a) was 6.7% vs. 50.0% (p<0.001) without a difference in median hospital stay (9 vs. 10 days, p=0.542). Readmission rates were 4.4% vs. 30.0% (p=0.003). Survival rates were 100% vs. 80% (p<0.001) at 90-days, 91.5% vs. 66.7% (p=0.005) at 1-year, and 68.9% vs. 53.3% (p=0.024) at 3-years, respectively. In comparison between MIE only and no surgery groups, these survival rates from day of diagnosis were 80% vs. 100%, 68.6% vs. 67.1%, and 45.7% vs. 32.0% (p=0.290), respectively.

Conclusions

By operating patients unsuitable for open approach with MIE, the resection rate increased 11.1%. These high-risk patients had, however, higher early morbidity and reduced long-term survival compared to other operated patients. Though there seems to be long-term benefit of surgery compared to nonsurgical patients, we have to be cautious when offering surgery to those considered unfit for open surgery.

Infrared intraoperative fluorescence imaging using indocyanine green in thoracic surgery

Thoracic surgery faces many unique challenges that require innovative solutions. The increase in utilization of minimally invasive practices, poor overall cancer survival and significant morbidity of key operations remain key obstacles to overcome. Intraoperative fluorescence imaging is a process by which fluorescent dyes and imaging systems are used as adjuncts for surgeons in the operating room. Other surgical subspecialists have shown that intraoperative fluorescence imaging can be applied as a practical adjunct to their practices. Thoracic surgeons over the last 15 years have also used intraoperative fluorescence imaging for sentinel lymph node mapping, lung mapping, oesophageal conduit vascular perfusion and lung nodule identification. This review describes some of the key studies that demonstrate the applications of intraoperative near-infrared fluorescence imaging.

Benchmark values for transthoracic esophagectomy are not set as the defined "best possible"-a validation study

Background

Recently, benchmark values for low-comorbidity patients at high-volume centers were set to define "best achievable results" for transthoracic minimally invasive esophagectomy (MIE). We aimed to validate suggested benchmark values by comparing them to outcomes at a medium-volume center in Finland.

Methods

All MIEs (n=82) performed at Central Finland Central Hospital between September 2012 and November 2017 including 75 totally MIE and 7 hybrid procedures. The aim of the study was to compare the results to previously suggested benchmark parameters for postoperative morbidity measured with the Clavien-Dindo classification and comprehensive complication index. Target benchmark parameters were ≤55.7% for any complications, ≤30.8% for major complications (Clavien-Dindo ≥3a), ≤40.8% for 30-day and ≤42.8% for 90-day comprehensive complication index, ≤20% for anastomosis leak, ≤31.6% for pulmonary complications, ≤1.0% for 30-day mortality and ≤4.6% for 90-day mortality.

Results

Compared with benchmark patients, our patients were older (median 68 vs. 58 years), with more comorbidities. All parameters measuring complications showed better results in our study than benchmark values. Median intensive care unit stay of 1 (IQR, 1-1) and hospital stay of 9 (IQR, 9-12) days were also shorter. At least 1 complication developed in 45.1%, and 6.1% faced major morbidity. Median (IQR) comprehensive complication index for both 30 and 90 days was 0 (IQR, 0-20.9 days). Anastomosis leak and pulmonary complications were observed in 3.7% and 22.0%, respectively. The 30- and 90-day mortality was 1.2% (1/82).

Conclusions

Benchmark values assessing postoperative morbidity after MIE do not represent the defined "best achievable" results after completed learning curves.

Near-Infrared Lymphatic Mapping of the Recurrent Laryngeal Nerve Nodes in T1 Esophageal Cancer

BACKGROUND

It is still unclear that dissection of recurrent laryngeal nerve nodes is mandatory in patients with cT1 middle or lower thoracic esophageal squamous cell carcinoma when the nodes are negative in preoperative staging workup. We aimed to evaluate the feasibility of near-infrared image-guided lymphatic mapping of bilateral recurrent laryngeal nerve nodes.

METHODS

The day before operation, we injected indocyanine green (ICG) into the submucosal layer by endoscopy. At the time of upper mediastinal dissection, ICG-stained basins were identified along the bilateral recurrent laryngeal nerves and retrieved under guidance of the Firefly system. After the operation, remnant ICG-unstained basins were dissected from the specimen to assess the presence of metastasis.

RESULTS

Of 29 patients enrolled, ICG-stained basins could be identified in 25 patients (86.2%), and 6 of them (24.0%) had nodal metastasis; 4 in the right recurrent laryngeal nerve chain, 1 in the left recurrent laryngeal nerve chain, and 1 in both recurrent laryngeal nerve chains. On pathologic examination of 345 recurrent laryngeal nerve nodes, two metastatic nodes were identified in ICG-unstained basins along the left recurrent laryngeal nerve in a patient who had lymph node metastases in ICG-stained basins along both recurrent laryngeal nerves. Negative predictive value in detection of nodal metastasis was 100% for the right recurrent laryngeal nerve chain and 98.2% for the left recurrent laryngeal nerve chain.

CONCLUSIONS

Real-time assessment of recurrent laryngeal nerve nodes with near-infrared image was technically feasible, and we could detect lymphatic basins that most likely have nodal metastasis. Our technique might be useful in determining the optimal extent of lymphadenectomy.