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

Lymph Node Metastasis in Gastrointestinal Carcinomas: A View from a Proteomics Perspective

Lymph node metastasis (LNM) is one of the major prognostic factors in human gastrointestinal carcinomas (GICs). The lymph node-positive patients have poorer survival than node-negative patients. LNM is directly associated with the recurrence and poor survival of patients with GICs. The early detection of LNM in patients and designing effective therapies to suppress LNM may significantly impact the survival of these patients. The rapid progress made in proteomic technologies could be successfully applied to identify molecular targets for cancers at high-throughput levels. LC-MS/MS analysis enables the identification of proteins involved in LN metastasis, which can be utilized for diagnostic and therapeutic applications. This review summarizes the studies on LN metastasis in GICs using proteomic approaches to date.

A combined approach for individualized lymphadenectomy in gastric cancer patients

Introduction: Gastric cancer ranks as the fifth most common cancer globally. The presence of lymph node metastasis is a significant prognostic factor influencing survival. Postoperative morbidity and nodal staging accuracy are heavily affected by the extent of lymph node dissection. Our study aimed to explore the potential integration of two contemporary methods, sentinel node navigation surgery (SNNS) and the Maruyama Computer Program (MCP), to improve the accuracy of nodal staging. Materials and methods: We conducted a prospective data collection involving patients with gastric adenocarcinoma from 2008 to 2018 at the Department of Surgery, University of Debrecen, Hungary. Data from 100 consecutive patients were collected. The primary and secondary endpoints included evaluating the rate of node-negative patients and the diagnostic accuracy of our combined approach. Results: Sentinel node mapping was successful in 97 out of 100 patients. We found that using the threshold value of the Maruyama Index (MI) ≥ 28, all metastatic stations of sentinel-node-negative patients could be identified. Our method achieved 100% sensitivity and negative predictive value, with a specificity of 60.42% (95% CI = 46.31%-72.98%). Discussion: The combined application of SNNS and MCP has proven to be an effective diagnostic technique in the synergistic approach for identifying metastasis-positive lymph node stations. Despite its limitations, this combination may assist clinicians in customizing lymphadenectomy for gastric cancer patients.

Lateral pelvic sentinel lymph node biopsy using indocyanine green fluorescence navigation: can it be a powerful supplement tool for predicting the status of lateral pelvic lymph nodes in advanced lower rectal cancer

BACKGROUND

An innovative instrument for laparoscopy using indocyanine green (ICG) allows easy detection of sentinel lymph nodes (SLNs) in lateral pelvic lymph nodes (LPLNs). Here, we investigated the safety and efficacy of lateral pelvic SLN biopsy (SLNB) using ICG fluorescence navigation in advanced lower rectal cancer and evaluated the sensitivity and specificity of this technique to predict the status of LPLN.

METHODS

From April 1, 2017 to December 1, 2020, we conducted lateral pelvic SLNB using ICG fluorescence navigation during laparoscopic total mesorectal excision and lateral pelvic lymph node dissection (LLND) in 23 patients with advanced low rectal cancer who presented with LPLN but without LPLN enlargement. Data regarding clinical characteristics, surgical and pathological outcomes, lymph node findings, and postoperative complications were collected and analyzed.

RESULTS

We successfully performed the surgery using fluorescence navigation. One patient underwent bilateral LLND and 22 patients underwent unilateral LLND. The lateral pelvic SLN were clearly fluorescent before dissection in 21 patients. Lateral pelvic SLN metastasis was diagnosed in 3 patients and negative in 18 patients by frozen pathological examination. Among the 21 patients in whom lateral pelvic SLN was detected, the dissected lateral pelvic non-SLNs were all negative. All dissected LPLNs were negative in two patients without fluorescent lateral pelvic SLN.

CONCLUSION

This study indicated that lateral pelvic SLNB using ICG fluorescence navigation shows promise as a safe and feasible procedure for advanced lower rectal cancer with good accuracy, and no false-negative cases were found. No metastasis in SLNB seemed to reflect all negative LPLN metastases, and this technique can replace preventive LLND for advanced lower rectal cancer.

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.

Optimal extent of lymph node dissection in gastric cancer

Gastric cancer still remains a major cause of cancer-related deaths globally. Stage-adapted, individualized treatment is crucial to achieving optimal oncological outcomes. Postoperative morbidity and accurate nodal staging are heavily influenced by the extent of lymph node dissection. On one hand, insufficient lymphadenectomy may result in understaging and undertreatment of a patient, on the other hand, unnecessary lymph node dissection may result in a higher rate of postoperative complications. Approximately one-third of patients with gastric cancer undergoes an avoidable lymph node dissection. Many of the recent treatment updates in the management of gastric cancer have a major influence on both surgical and oncological approaches. Currently, a wide range of endoscopic, minimally invasive, and hybrid surgical techniques are available. The concept of sentinel node biopsy and utilization of the Maruyama Computer Program are significant components of stage-adapted gastric cancer surgery. Likewise, centralization and application of national guidelines, widespread use of neoadjuvant therapy, and the stage migration phenomenon are serious concerns to be discussed. Our goal is to review the available surgical strategies for gastric cancer, with a primary focus on lymphadenectomy.

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.

Excitation coil for sentinel lymph node harvesting: design, digital twin and prototype

A recently developed prototype (Laparoscopic Differential Magnetometer, in short LapDiffMag) identifies magnetic tracer accumulated inside sentinel lymph nodes (SLNs) during clinical laparoscopic procedures. The LapDiffMag relies on excitation of superparamagnetic iron oxide nanoparticles (SPIONs) and subsequent laparoscopic detection based on a nonlinear detection principle. The prototype uses an excitation coil to generate a magnetic field needed to activate SPIONs. This study reports on the process of developing a new excitation coil by describing the design choices based upon clinical requirements, by modeling delivered magnetic field using digital twin, and by comparing the magnetic fields of modeled and manufactured prototype. Digital twin technology was used to produce relevant and reliable data to demonstrate the safety and effectiveness of the excitation coil. The magnetic field originating from manufactured prototype was validated at two different heights above the excitation coil and have shown a good concordance to the data generated by its digital twin. Clinical Relevance- Current standard-of-care for a variety of tumor types consists of minimally invasive radical resection of primary tumor and regional lymph nodes (LNs). The newly introduced excitation coil will (after full validation) enable minimally invasive harvesting of sentinel LNs by means of magnetic tracer detection.

Oxygen Imaging for Non-Invasive Metastasis Detection

Sentinel lymph node (SLN) biopsy is an integral part of treatment planning for a variety of cancers as it evaluates whether a tumor has metastasized, an event that significantly reduces survival probability. However, this invasive procedure is associated with patient morbidity, and misses small metastatic deposits, resulting in the removal of additional nodes for tumors with high metastatic probability despite a negative SLN biopsy. To prevent this over-treatment and its associated morbidities for patients that were truly negative, we propose a tissue oxygen imaging method called Photoacoustic Lifetime Imaging (PALI) as an alternative or supplementary tool for SLN biopsy. As the hyper-metabolic state of cancer cells significantly depresses tissue oxygenation compared to normal tissue even for small metastatic deposits, we hypothesize that PALI can sensitively and specifically detect metastases. Before this hypothesis is tested, however, PALI's maximum imaging depth must be evaluated to determine the cancer types for which it is best suited. To evaluate imaging depth, we developed and simulated a phantom composed of tubing in a tissue-mimicking, optically scattering liquid. Our simulation and experimental results both show that PALI's maximum imaging depth is 16 mm. As most lymph nodes are deeper than 16 mm, ways to improve imaging depth, such as directly delivering light to the node using penetrating optical fibers, must be explored.

Pathologic Lymph Node Staging of Gastric Cancer

OBJECTIVES

The TNM classification is the main tool for lymph node (LN) staging in gastric cancer (GC). However, alternative LN staging systems have been proposed, and the role of features other than the number of metastatic LNs is being investigated. Our aim is to discuss the main challenges of LN assessment in GC.

METHODS

Comprehensive review of the literature on alternative LN staging systems, examined LNs, sentinel LN (SLN) biopsy, LN micrometastases (LNMIs), extracapsular extension (ECE), and tumor deposits (TDs) in GC.

RESULTS

Many controversies exist regarding LN assessment in GC. The TNM classification shows excellent prognostic performance, but alternative prognostic methods such as the LN ratio or log odds of positive LNs have demonstrated to be better than the TNM system in terms of prognostic accuracy. The value of SLN biopsy and LNMIs in GC is still unclear, and several challenges concerning their clinical impact and pathologic analysis must be overcome before their introduction in clinical practice. Most authors have identified ECE and TDs as independent prognostic factors for survival in GC.

CONCLUSIONS

Further studies should be performed to evaluate the impact of these features on the TNM classification and patient outcomes, as well as to standardize alternative LN staging systems.

Controversies in EUS: Do we need miniprobes?

This is the fifth in a series of papers entitled "Controversies in EUS." In the current paper, we deal with high-resolution catheter probes, otherwise known as EUS miniprobes (EUS-MPs). The application of miniprobes for early carcinomas in the entire intestinal tract, for subepithelial lesions, and for findings in the bile duct and pancreatic duct as well as endobronchial use is critically discussed. Submucous lesions, especially in the colon, but also early carcinomas in special cases are considered the most important indications. The argument is illustrated by numerous examples.

Severe anaphylactic reaction after blue dye injection for sentinel lymph node biopsy in breast surgery: Report of two cases and literature review

Anaphylactic reactions, and especially the severe ones (types III and IV), should be kept in mind as considerable adverse effects while using blue dyes for SLNB.

Laparoscopic Probe for Sentinel Lymph Node Harvesting using Magnetic Nanoparticles

OBJECTIVE

Sentinel lymph node harvesting is an essential step in the surgical treatment of a growing number of malignancies. Various techniques are available to facilitate this purpose. The present study reports a new laparoscopic technique for lymph node harvesting using magnetic nanoparticles containing a superparamagnetic iron-oxide core and dextran coating. This study assesses the clinical relevance of the prototype and provides input for further technological development on the way to clinical implementation.

METHODS

A laparoscopic differential magnetometer prototype was built, utilizing a nonlinear detection principle (differential magnetometry) for magnetic identification of lymph nodes. The iron content sensitivity, depth & spatial sensitivity, and angular sensitivity were analyzed to investigate clinical options.

RESULTS

The minimum detectable amount of iron was 9.8 g at a distance of 1 mm. The detection depth was 5, 8, and 10 mm for samples containing 126, 252, and 504 g iron, respectively. The maximum lateral detection distance was 5, 7, and 8 mm for samples containing 126, 252, and 504 g iron, respectively. A sample containing 504 g iron was detectable at all angulations assessed (0, 30, 60 and 90).

CONCLUSION

The laparoscopic differential magnetometer demonstrates promising results for further investigation and development towards laparoscopic lymph node harvesting using magnetic nanoparticles.

SIGNIFICANCE

The laparoscopic differential magnetometer facilitates a novel method for sentinel lymph node harvesting, which helps to determine prognosis and treatment of cancer patients.

Value of preoperative gastroscopic carbon nanoparticles labeling in patients undergoing laparoscopic radical gastric cancer surgery

BACKGROUND AND OBJECTIVES

Lymph node metastasis is crucial for gastric cancer. We aim to explore the value of preoperative gastroscopic carbon nanoparticles labeling in patients undergoing laparoscopic radical gastric cancer surgery.

METHODS

1199 cases undergoing laparoscopic radical gastric cancer surgery were retrospectively analyzed. 214 cases received preoperative gastroscopic carbon nanoparticles labeling. The number of total lymph nodes detected, positive lymph nodes, N staging, and operation time were analyzed.

RESULTS

The patients received carbon nanoparticles labeling had more total lymph nodes detected (27.9 ± 6.5 vs 22.2 ± 4.0; P ＜ 0.001) and shorter operation time (185.9 ± 27.8min vs 218.7 ± 69.2min; P ＜ 0.001) compared with the control group. In addition, preoperative endoscopic carbon nanoparticles labeling improved the diagnosis rate of synchronous multiple gastric cancer (2.8% vs 0.4%; P ＜ 0.001).

CONCLUSIONS

Preoperative endoscopic carbon nanoparticles tracer labeling is of great value in patients undergoing laparoscopic radical gastric cancer surgery. It shortens the operation time, increases the number of total lymph nodes detected for more accurate pathological TNM staging, and finds some cases of synchronous multiple gastric cancer.

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.

Prognostic impact of anatomical extent of metastatic lymph node on gastric cancer: a propensity score matching study

PURPOSE

Current gastric cancer staging systems overlook the anatomic extent of metastatic lymph nodes (AEMLNs). This study aimed to analyze the prognostic impact of AEMLNs on gastric cancer (GC).

METHODS

GC patients with metastatic lymph nodes (MLNs) undergoing curative surgery were retrospectively reviewed and assigned to perigastric (MLNs in station 1-6, PG) and extraperigastric group (7-12, with or without MLNs in PG area, EPG). Overall survival (OS), disease-free survival (DFS) and recurrence patterns were compared before and after 1:1 propensity score matching (PSM).

RESULTS

662 patients were enrolled, 341 (51.5%) and 321 (48.5%) of whom were in the PG and EPG, respectively. After PSM (n = 195), EPG showed poorer 5-year OS (43.4% vs 54.5%, p = 0.014) and DFS (65.0% vs 73.4%, p = 0.068) than PG. EPG had higher incidence of peritoneal recurrence (PR) than PG (19.4% vs 7.4%, p = 0.002). Multivariate analysis identified AEMLNs as prognostic factor for OS [HR = 1.409, 95% confidence interval (CI) 1.062-1.868), DFS (HR = 1.600, 95% CI 1.059-2.416) and PR (HR = 3.708, 95% CI 1.685-8.160).

CONCLUSIONS

The anatomic extent of metastatic lymph nodes has an independent prognostic role for GC. Including this element may improve the accuracy of current staging systems.

Ex vivo perfusion of human lymph nodes†

In a recent study published in The Journal of Pathology, Barrow-McGee et al described a feasibility study of a real-time ex vivo perfusion model of the axillary lymph nodes (ALNs) from breast cancer patients for immune-oncological investigations. The study showed that perfused ALNs remain viable for up to 24 h, and perfusion of therapeutic antibodies confirmed the ability to reach ALN-resident cells. This work is a highly encouraging demonstration of feasibility for further research into lymphatic system function, with applications to immune function, vaccinations, and cancer. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.