Feasibility study of sentinel lymph node biopsy in esophageal cancer with conservative lymphadenectomy

Sentinel Lymph Node Mapping in Esophageal Cancer: Current Status and Future Directions

OBJECTIVE

This review provides a comprehensive discussion about the importance of adequate lymphadenectomy, its anatomic and oncologic significance, principles and rationale of sentinel lymph node mapping, current evidence stratified by tracer substrate, challenges, and future directions. Esophageal cancer has one of the worst cancer-related survival rates, and nodal status is the single most significant prognostic factor. Submucosal penetration generally demands esophagectomy, often following neoadjuvant therapy in the presence of deeper extension. Guidelines recommend resecting ≥15 lymph nodes. Variability in surgical approach and dissection in concert with aberrant esophageal lymphatic anatomy make adequate lymphadenectomy difficult.

METHODS

A narrative review was conducted to explore existing literature regarding lymphadenectomy with its requisite anatomic and oncologic significance in esophageal cancer, as well as the rationale for and present state of sentinel lymph node mapping stratified by substrates. Tables and figures were constructed by the authors using Microsoft Office applications and Biorender software, respectively.

RESULTS

Sentinel lymph node mapping exploits the tumoral lymphatic network to identify the nodes most prone to metastasis, directing further dissection. Targeting sentinel lymph nodes with dyes, radiotracers, or hybrid tracers can assist surgeons with lymphadenectomy, potentially improving staging accuracy and personalizing care to individual anatomy.

CONCLUSIONS

While this approach would benefit from larger studies and long-term data, early evaluations suggest improved detection of metastases outside the en bloc field without significantly increasing morbidity.

Sentinel node navigation surgery in esophageal cancer

Over the last 20 years, the sentinel node (SN) concept has been widely applied to the surgical staging of both breast cancer and melanoma. However, the validity of this concept has been controversial for esophageal cancer, because SN mapping for esophageal cancer is not considered to be technically easy because of the complicated multidirectional lymphatic networks of the esophagus and mediastinum. Nevertheless, studies including meta-analyses indicated that SN mapping may be feasible in early esophageal cancer. Transthoracic esophagectomy with three-field lymphadenectomy was developed as a potential curative procedure for thoracic esophageal cancer. However, this highly invasive procedure might increase morbidity and reduce patients' quality of life (QOL) after esophagectomy. Although further validation based on multicenter trials using the standard protocol of SN mapping for esophageal cancer is required, SN navigation surgery would enable us to carry out personalized and limited lymph node dissection which might reduce morbidity and maintain patients' QOL.

Update on the indications and results of sentinel node mapping in upper GI cancer

The clinical utilization of sentinel node (SN) mapping for early esophageal cancer or gastric cancer has been unclear for a long time. However, previous investigations regarding SN mapping of these cancers have shown relatively good results with regard to the detection rate and diagnostic accuracy for determining the lymph node status. SN mapping helps obtain information about individual metastatic status and allows the modification of the operation in early-stage upper gastrointestinal (GI) disease. Radio-guided methods for identifying SNs in early esophageal cancer have been established via endoscopic injection of technetium-99m tin colloid. Previous studies have reported that the SN concept seems valid, and radio-guided SN mapping can be feasible in cT1N0 esophageal cancer. SN navigation surgery are believed to have potential as strategies for minimally invasive modified surgery for early esophageal cancer. A Japanese study group conducted a prospective multicenter trial of SN mapping for early gastric cancer using a dual tracer method with radioactive colloid and blue dyes; they demonstrated a high detection rate and accuracy for determining the metastatic status based on SN mapping. Subsequently, minimized gastrectomy, including partial gastrectomy and segmental gastrectomy with individualized selective and modified lymphadenectomy for early gastric cancer with a negative SN has been performed to evaluate the long-term survival and postoperative quality of life (QOL) in a multicenter prospective trial. This study verified the SN concept in early-stage upper GI disease with cN0 and found that function-preserving esophagectomy or gastrectomy may help maintain patients' post-surgical QOL.

Pilot-study on the feasibility of sentinel node navigation surgery in combination with thoracolaparoscopic lymphadenectomy without esophagectomy in early esophageal adenocarcinoma patients

High-risk submucosal esophageal adenocarcinoma's might be treated curatively by means of radical endoscopic resection, followed by thoracolaparoscopic lymphadenectomy without concomitant esophagectomy. A preclinical study has shown the feasibility and safety of this approach; however, no studies are performed in a clinical setting. In addition, sentinel node navigation surgery could be valuable in tailoring the extent of the lymphadenectomy. This study aimed to evaluate the feasibility and safety of thoracolaparoscopic lymphadenectomy without esophagectomy (phase I) and sentinel node navigation surgery (phase II) in patients with early esophageal adenocarcinoma. Patients with T1N0M0 early esophageal adenocarcinoma scheduled for esophagectomy without neoadjuvant therapy were included. Phase I: Two-field, esophagus preserving, thoracolaparoscopic lymphadenectomy was performed, followed by esophagectomy in the same session. Primary outcome parameters were the number of lymph nodes resected, and number of retained lymph nodes in the esophagectomy specimen. Phase II: A radioactive tracer was injected endoscopically the day before surgery. Static imaging was performed 15 and 120 minutes after injection. The day of surgery, sentinel node navigation surgery followed by esophagectomy was performed. Primary outcome parameters were the percentage of patients with a detectable sentinel node, and the concordance between static imaging and probe-based detection of sentinel node. Phase I: Five patients were included, and a median of 30 (IQR: 25-46) lymph nodes was resected. A median of 6 (IQR: 2-9) retained lymph nodes was found in the esophagectomy specimen. No acute adverse events occurred, but near the end of lymphadenectomy esophageal discoloration was observed, possibly indicating ischemia. Phase II: In all five included patients sentinel nodes could be visualized and resected, at a median of 3 (IQR: 2-5) locations. There was a high concordance between imaging and probe-based detection of sentinel nodes. In conclusion, sentinel node navigation surgery followed by lymphadenectomy without concomitant esophagectomy seems feasible in patients with high-risk submucosal early esophageal adenocarcinoma. More evidence is however needed before applying this technique in clinical practice.

Macrophage-Targeted Indocyanine Green-Neomannosyl Human Serum Albumin for Intraoperative Sentinel Lymph Node Mapping in Porcine Esophagus

BACKGROUND

The sentinel lymph node (SLN) concept has been proposed to avoid unnecessary invasive LN dissection in surgery for esophageal cancer. This study evaluated a new macrophage-targeting fluorescent agent, indocyanine green-neomannosyl human serum albumin (ICG:MSA), for SLN mapping using a custom-made intraoperative color and fluorescence-merged imaging system (ICFIS) in porcine esophagus.

METHODS

The LN targeting ability of ICG:MSA, indocyanine green-human serum albumin (ICG:HSA), and ICG was examined in vitro using the U937 differentiated monocyte cell line and in vivo in a mouse footpad model using fluorescence imaging. SLN identification in rabbit esophagus was then performed using ICG:MSA, ICG:HSA, and ICG. Finally, intraoperative SLN detection was conducted in porcine esophagus after esophagoscopic injection of ICG:MSA.

RESULTS

The fluorescence signal of U937 cells treated by ICG:MSA was significantly higher than that of ICG or ICG:HSA (ICG: 1.0 ± 0.37; ICG:HSA: 3.4 ± 0.28, ICG:MSA: 6.8 ± 1.61; ICG to ICG:HSA, p = 0.03; ICG:HSA to ICG:MSA, p = 0.04; ICG to ICG:MSA, p = 0.0009). ICG:MSA was retained in popliteal LNs as long as 3 h, while ICG rapidly diffused through the entire mouse lymphatic system within 5 min. Esophageal SLN was detected within 15 min after injection of either ICG or ICG:MSA, but ICG:MSA provided more distinguishable images of LNss than ICG in rabbit esophagus. The SLN was also successfully detected in all porcine esophagus; the mean number of SLNs identified per esophagus was 1.6 ± 0.55.

CONCLUSIONS

ICG:MSA has more specific macrophage-targeting properties, which could overcome the limitation of the low SLN retention of ICG, and could provide more precise real-time SLN detection during esophageal cancer surgery.

Sentinel lymph node in oesophageal cancer-a systematic review and meta-analysis

BACKGROUND

Sentinel lymph nodes (SLNs) have been used to predict regional lymph node metastasis in patients with melanoma and breast cancer. However, the validity of the SLN hypothesis is still controversial for oesophageal cancer. We performed this meta-analysis to evaluate the feasibility and accuracy of radio-guided SLN mapping for oesophageal cancer.

METHODS

A systematic search was conducted using MEDLINE, PubMed, EMBASE, Current Contents Connect, Cochrane library, Google scholar, Science Direct, and Web of Science. Original data was abstracted from each study and used to calculate a pooled event rates and 95% confidence interval (95% CI).

RESULTS

The search identified 23 relevant articles. The overall detection rate was 0.93 (95% CI: 0.894-0.950), sensitivity 0.87 (95% CI: 0.811-0.908), negative predictive value 0.77 (95% CI: 0.568-0.890) and the accuracy was 0.88 (95% CI: 0.817-0.921). In the adenocarcinoma cohort, detection rate was 0.98 (95% CI: 0.923-0.992), sensitivity 0.84 (95% CI: 0.743-0.911) and the accuracy was 0.87(95% CI: 0.796-0.913). In the squamous cell carcinoma group, detection rate was 0.89 (95% CI: 00.792-0.943), sensitivity 0.91 (95% CI: 0.754-0.972) and the accuracy was 0.84 (95% CI: 0.732-0.914).

CONCLUSIONS

It is possible to identify and obtain a SLN before neoadjuvant therapy in oesophageal cancer. However, further work is needed to optimize radiocolloid type, refine the technique and develop a quick and accurate way to determine SLN status intraoperatively. This technique has to be further evaluated before it can be applied widely.

Sentinel node navigation surgery in early-stage esophageal cancer

The sentinel node (SN) concept has revolutionized the surgical staging of both melanoma and breast cancer over the past two decades. However, the validity of the SN hypothesis has been controversial for esophageal cancer, because SN mapping for esophageal cancer is technically complicated, and the number of early-stage esophageal cancer is very limited. Nevertheless previous studies nicely demonstrated that SN mapping may be feasible in patients with early-stage esophageal cancer. Transthoracic extended esophagectomy with three-field radical lymph node dissection has been recognized as a curative procedure for thoracic esophageal cancer in Japan. However, uniform application of this highly invasive procedure might increase the morbidity and markedly reduce the quality of life (QOL) after surgery. Although further accumulation of evidence based on multicenter clinical trials using a standard protocol is needed, SN mapping and SN navigation surgery would provide significant information to perform individualized selective lymphadenectomy which might reduce the morbidity and retain the patients' QOL. In addition, technical innovation including the development of new tracers is expected to confirm the accuracy and reliability of SN mapping in esophageal cancer.

Sentinel lymph node biopsy in esophageal cancer: should it be standard of care?

INTRODUCTION

Sentinel node mapping is established in some superficial cancers but remains controversial in harder-to-access solid tumors. There are an increasing number of recent studies suggesting that isolated tumor cells have prognostic significance in predicting poor survival, in breast cancer, esophageal cancer, and others. It is for this reason that we have persevered with the sentinel lymph node concept in our esophagectomy cancer patients, and we report our results since 2008.

METHODS

Thirty-one of 32 consecutive patients underwent resection for invasive esophageal cancer along with sentinel lymph node retrieval (resection rate, 97%). Peritumoral injection of (99m)Tc antimony colloid was performed by upper endoscopy prior to the operation. A two-surgeon synchronous approach via a right thoracotomy and laparotomy was performed with a conservative lymphadenectomy. Sentinel lymph nodes were identified with a gamma probe both in and ex vivo, and sent off separately for three serial sections and immunohistochemistry with AE1/AE3.

RESULTS

The median patient age was 63.4 years (range, 45-75 years). Most patients (81%) had an adenocarcinoma, and 61% had received neoadjuvant therapy. At least one sentinel lymph node (median, 3) was identified in 29 of 31 patients (success rate, 94%). Sentinel nodes were present in more than one nodal station in 16 patients (55%). One false negative case led to a sensitivity of 90%. In 28 of 29 patients, the sentinel lymph node accurately predicted findings in non-sentinel nodes (accuracy, 96%).

CONCLUSIONS

Sentinel lymph node biopsy is both feasible and accurate in esophageal resections with conservative lymphadenectomy. It allows targeted serial sectioning and immunohistochemical studies of those nodes and should become standard of care in patients undergoing esophagectomy for esophageal cancer.