Factors associated with detection failure and false-negative sentinel node biopsy findings in gastric cancer: results of prospective single center trials

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.

A prediction model for lymph node metastasis in early-stage gastric cancer: Toward tailored lymphadenectomy

BACKGROUND

The aim of this study was to develop a prediction model for the presence and location of lymph node metastasis (LNM) in early gastric cancer.

METHOD

We reviewed medical records of 4 929 patients who underwent radical gastrectomy for early gastric cancer. Variables of age, sex, lymphatic invasion, depth of invasion, location, gross type, differentiation, and tumor size were analyzed. Logistic regression analysis was used to determine independent predictors of LNM at each LN station.

RESULT

Overall incidence of LNM was 9.1% (448/4 929 patients). For the presence of LNM, risk factors of age, sex, lymphatic invasion, depth of invasion, anatomical part, gross ulceration, size, and tumor differentiation were significantly associated with LNM. The area under the curve (AUC) for predicting LNM after validation was 0.834 for the test set. For the location of LNM, age, sex, lymphatic invasion, depth of invasion, anatomical part, circumferential portion, gross type, differentiation, and tumor size were significantly associated with LNM. The AUC of each LN station was favorable with the test set.

CONCLUSION

Predicting the location of metastatic LNs appeared to be possible in patients with early gastric cancer.

Sentinel Lymph Node Sampling for Early Gastric Cancer-Preliminary Results of A North American Prospective Study

INTRODUCTION

Although endoscopic resection for early gastric cancer is well established, anatomical resection with regional lymphadenectomy is recommended for lesions at high risk for occult lymph node metastasis (e.g., lymphovascular invasion, poor grade, and deep submucosal invasion). However, 75-95% high-risk early gastric cancer (HR-EGC) patients ultimately have node-negative disease and could potentially have undergone organ-sparing resection. Due to the inadequacy of standard modalities to reliably rule out nodal metastases in HR-EGC patients, sentinel lymph node (SLN) sampling was developed in Asia with promising results. However, the applicability of this technique in the West has been brought into question due to potential differences in tumor histology and body habitus. This prospective study aimed to test SLN sampling for North American EGC patients.

METHODS

All patients with biopsy-confirmed T0-2 N0-1 M0 gastric adenocarcinoma at the Montreal General Hospital-McGill University Health Centre were eligible for enrollment. Esophageal and GEJ cancers were excluded due to the high rate of intrathoracic lymph node involvement. Peritumoral submucosal injection with T⁹⁹ radiocolloid was performed endoscopically 24-30 h prior to surgery. Methylene blue dye injection was performed after induction of anesthesia. SLN basins were identified as those having > 10% of baseline tumor radiation signal or blue color, or both. After basins were individually removed, standard laparoscopic anatomical resection was then performed with D2 lymphadenectomy. ( ClinicalTrials.gov identifier: NCT03049345). Data are presented as median (interquartile range).

RESULTS

From July 2016-April 2018, 253 patients with esophagogastric adenocarcinoma were evaluated. Of these, 10 met inclusion criteria (90% male, age 66(30) years). Subtotal gastrectomy was performed in nine patients (90%) and length of stay was 4 (2) days. At least one SLN basin was identified in nine cases (90%). The median #SLN basins identified was 2(2) with a median of 5(5) total SLNs retrieved per patient. In the one case for which no SLN basins were identified, only blue dye injection was used, whereas SLNs were identified in all cases using the dual tracer method. Final T-stage was pT1b/T2 in four (40%), pT1a in two (20%), and Tx in four (40%). Two patients (20%) had lymph node metastases on final pathological analysis, both of which were identified by SLN sampling (accuracy 100%; false negative rate 0%). No adverse events related to SLN retrieval were identified.

CONCLUSIONS

This study represents the first prospective feasibility evaluation of sentinel lymph node sampling for early gastric cancer in North America with promising preliminary results. The dual tracer method was superior to single agent blue dye in identifying sentinel nodal basins. Considerable further study is necessary to verify the safety and utility of SLN mapping in North American patients with early gastric adenocarcinoma.

Which Factors Are Important for Successful Sentinel Node Navigation Surgery in Gastric Cancer Patients? Analysis from the SENORITA Prospective Multicenter Feasibility Quality Control Trial

Background

We investigated the results of quality control study prior to phase III trial of sentinel lymph node navigation surgery (SNNS).

Methods

Data were reviewed from 108 patients enrolled in the feasibility study of laparoscopic sentinel basin dissection (SBD) in gastric cancer. Seven steps contain tracer injection at submucosa (step 1) and at four sites (step 2) by intraoperative esophagogastroduodenoscopy (EGD), leakage of tracer (step 3), injection within 3 minutes (step 4), identification of at least one sentinel basin (SB) (step 5), evaluation of sentinel basin nodes (SBNs) by frozen biopsy (step 6), and identification of at least five SBNs at back table and frozen sections (step 7).

Results

Failure in step 7 (n = 23) was the most common followed by step 3 (n = 15) and step 6 (n = 13). We did not find any differences of clinicopathological factors between success and failure group in steps 1~6. In step 7, body mass index (BMI) was only the significant factor. The success rate was 97.1% in patients with BMI  <  23 kg/m² and 80.3% in those with BMI ≥ 23 kg/m² (P = 0.028).

Conclusions

Lower BMI group showed higher success rate in step 7. Surgeons doing SNNS should be cautious when evaluating sufficient number of SBN in obese patients.

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.

Lymph node mapping with carbon nanoparticles and the risk factors of lymph node metastasis in gastric cancer

The study aimed to examine the applicability of carbon nanoparticles as a tracer for lymph node mapping and the related factors of lymph node and No.8p subgroup metastasis in patients with gastric cancer. Clinical data of 50 patients with gastric cancer, who had not received treatment preoperatively and underwent gastrectomy in Department of Gastrointestinal Surgery, Wuhan Union Hospital, between October 2014 and August 2015, were retrospectively analyzed. These patients were found to have no distant metastasis preoperatively. Thirty-five out of 50 patients were subjected to lymphatic mapping technique using carbon nanoparticles as the tracer, and the rest 15 cases did not experience the lymphatic mapping and served as controls. The sensitivity, specificity, false positive rate and false negative rate were calculated according to the number of lymph nodes, and the staining and metastasis condition of lymph nodes. The diagnostic value of carbon nanoparticles on metastatic lymph nodes was evaluated. The relationship between the metastasis of lymph nodes or subgroup No.8p lymph nodes and clinicopathologic features was analyzed by χ²-test or Fisher's exact test. All patients underwent D2 surgery (lymph node dissection including all the group 1 and group 2 nodes) plus the dissection of the subgroup No.8p lymph nodes. It was found that the average number of harvested lymph nodes in lymphatic mapping technique group (45.7±14.5) was greater than that in control group (39.2±11.7), but the difference was not significantly different (P=0.138>0.05). The success rate, the accuracy, sensitivity, specificity and false negative rate was 97%, 57%, 28%, 62% and 72% respectively. The metastasis of lymph nodes was correlated to the depth of cancer invasion (T stage) (P=0.004<0.05), and the metastasis of No.8p lymph nodes was correlated to the extent of lymph node involvement (N stage) (P=0.007<0.05). Six cases had lymph node metastasis in subgroup No.8p, and their TNM stages and clinical stages were as follows: T1N2M0 IIA, T3N3M0 IIIB, T4aN3M0 IIIC, T4aN3M0 IIIC, T4aN3M0 IIIC, and T4bN3M0 IIIC. In conclusion, our study indicated that carbon nanoparticles failed to show good selectivity for metastatic lymph nodes; the result of lymphatic mapping does not achieve a satisfactory performance; the incidence of lymph node metastasis may increase, accompanying with the increase of the depth of cancer invasion; No.8p lymph node metastasis tends to occur for gastric carcinoma patients with the extent of lymph node metastasis over N2 stage.

Comparison of the Diagnostic Value Between Real-Time Reverse Transcription-Polymerase Chain Reaction Assay and Histopathologic Examination in Sentinel Lymph Nodes for Patients With Gastric Carcinoma

OBJECTIVES

Sentinel lymph node (SLN)-based diagnosis in gastric cancers has shown varied sensitivities and false-negative rates in several studies. Application of the reverse transcription-polymerase chain reaction (RT-PCR) in SLN diagnosis has recently been proposed.

METHODS

A total of 155 SLNs from 65 patients with cT1-2, N0 gastric cancer were examined. The histopathologic results were compared with results obtained by real-time RT-PCR for detecting molecular RNA (mRNA) of cytokeratin (CK)19, carcinoembryonic antigen (CEA), and CK20.

RESULTS

The sensitivity and specificity of the multiple marker RT-PCR assay standardized against the results of the postoperative histological examination were 0.778 (95% confidence interval [CI], 0.577-0.914) and 0.781 (95% CI, 0.700-0.850), respectively. In comparison, the sensitivity and specificity of intraoperative diagnosis were 0.819 (95% CI, 0.619-0.937) and 1.000 (95% CI, 0.972-1.000), respectively. The positive predictive value of the multiple-marker RT-PCR assay was 0.355 (95% CI, 0.192-0.546) for predicting non-SLN metastasis, which was lower than that of intraoperative diagnosis (0.813, 95% CI, 0.544-0.960).

CONCLUSIONS

The real-time RT-PCR assay could detect SLN metastasis in gastric cancer. However, the predictive value of the real-time RT-PCR assay was lower than that of precise histopathologic examination and did not outweigh that of our intraoperative SLN diagnosis.

Prospective Multicenter Feasibility Study of Laparoscopic Sentinel Basin Dissection for Organ Preserving Surgery in Gastric Cancer: Quality Control Study for Surgical Standardization Prior to Phase III Trial

The clinical application of sentinel node biopsies in early gastric cancer is still controversial even though it appears promising. This study was conducted as a prerequisite quality control for surgical standardization of laparoscopic sentinel basin dissection (SBD) prior to the initiation of a phase III trial.Laparoscopic SBD was performed in patients with preoperative stage T1-2N0 and tumor size <4 cm in diameter. Intraoperative endoscopic submucosal injection of a standardized dual tracer was administered. All retrieved sentinel basin nodes (SBN) were investigated with intraoperative frozen hematoxylin and eosin (H&E) staining. A strict checklist consisting of 7 essential steps was followed during laparoscopic SBD as the quality control study for a phase III trial. Completion of all essential steps in the checklist for 10 cases was used to define a qualified institution.Seven institutions participated and 112 patients were enrolled in this study. However, 4 patients were excluded owing to screening failure. The mean number of cases required for institutional qualification was 15 cases (range, 13-20 cases). Sentinel basins (SB) were detected and dissected in 100 of the 108 patients (92.6%); the median number of SB and SBN was 2 and 7, respectively. Lymph node metastases were detected in 10 patients by postoperative permanent H&E staining and they were detected by SBD in all 10 patients. Frozen results of SBN were compatible with permanent staining reports.Laparoscopic SBD is feasible and demonstrated improved sensitivity in detecting metastatic lymph nodes compared to the previous study. A future phase III randomized trial comparing laparoscopic SBD with organ-preserving gastrectomy and laparoscopic standard gastrectomy seems promising for qualified institutions.

Biopathologic features and clinical significance of micrometatasis in the lymph node of early gastric cancer

AIM: To evaluate the biopathologic features and clinical significance of nodal micrometastasis (MI) in early gastric cancer (EGC).

METHODS: Among 1022 EGC patients who underwent gastrectomy with lymphadenectomy of D1 + β or more from March 2001 to December 2005 at the Korean National Cancer Center, available nodal metastasis was found in 90 pT1N1 patients. Nodal metastasis was confirmed by immunohistochemistry (IHC) with cytokeratin and patients were classified into MI and macrometastasis (MA) groups based on the main tumor burden according to the 6^th International Union Against Cancer/American Joint Committee on Cancer staging system; the main tumor burden with a diameter of greater than 0.2 mm but no greater than 2 mm as MI, and greater than 2 mm as MA of the representative metastatic node. Proliferative and apoptotic activities of the primary tumor and the nodal metastasis were measured by IHC with Ki-67 and terminal deoxynucleotidyl transferase dUTP nick end labeling, respectively. Biopathologic and clinical features of the patients were analyzed and compared between MI and MA groups. Patients with recurrence were compared with those without recurrence to identify risk factors for recurrence.

RESULTS: Thirty-seven patients showed MI and the other 53 patients revealed MA in the lymph node; the incidence of patients with MI and MA was 41.1% and 58.9%. The main tumor burden was 0.9 and 4.6 mm in the representative metastatic node, respectively. Japanese N2 stations were more frequently involved in MA group (20.9%) than in MI group (10.3%) but the difference was not statistically different (P = 0.338). Proliferative and apoptotic activities of MI were decreased than those of MA (26.7% vs 40.5%, P = 0.004 and 1.0% vs 3.0%, P < 0.001, respectively). However, nodal MI in the current study showed a relatively high proliferative activity and an equivalent apoptotic activity compared to other cancers in the previously published studies. Recurrence was observed in 6 patients during the mean follow up period of 87.6 ± 26.2 mo. The recurrence was significantly associated with the presence of MA (P = 0.041) and lymphovascular invasion of the primary tumor (P = 0.032).

CONCLUSION: Lymphadenectomy of D1 + β or more might be necessary in patients with MI in sentinel node to prevent recurrence by clearing MI involving Japanese N2 station.

High false-negative proportion of intraoperative histological examination as a serious problem for clinical application of sentinel node biopsy for early gastric cancer: final results of the Japan Clinical Oncology Group multicenter trial JCOG0302

BACKGROUND

To evaluate the feasibility and accuracy of diagnosis using sentinel node (SN) biopsy in T1 gastric cancer, a multicenter trial was conducted by the Japan Clinical Oncology Group (JCOG).

METHODS

Sentinel node biopsy with indocyanine green (ICG) was performed in patients with T1 gastric cancer. Green-stained nodes (GNs), representing SNs, were removed first, and gastrectomy with lymphadenectomy was then performed. GNs in one plane (with the largest dimension) were histologically examined intraoperatively by frozen section with hematoxylin and eosin (H&E) stain. All harvested lymph nodes (GNs and non-GNs) were histologically examined by paraffin section after surgery. The primary endpoint was to determine the proportion of false negatives, which was defined as the number of patients with negative GNs by frozen section divided by those with positive GNs and/or positive non-GNs by paraffin section. The sample size was set at 1,550, based on the expected and threshold value as 5 and 10 % in the proportion of false negatives.

RESULTS

Accrual was suspended when 440 patients were enrolled because the proportion of false negatives was high. In the primary analysis, the proportion of false negatives was 46 % (13/28) after a learning period with 5 patients for each institution. Seven of 13 patients had nodal metastases outside the lymphatic basin. False negatives remained at 14 % (4/28) even by examining additional sections of GNs by paraffin section.

CONCLUSIONS

The proportion of false negatives was much higher than expected. Intraoperative histological examination using only one plane is not an appropriate method for clinical application of SN biopsy in gastric cancer surgery.

Intraoperative diagnosis using sentinel node biopsy with indocyanine green dye in gastric cancer surgery: an institutional trial by experienced surgeons

BACKGROUND

Reliable indicators that can intraoperatively determine the absence of nodal metastasis are in great demand to avoid unnecessary lymphadenectomy. However, little has been reported about the intraoperative diagnostic performance of sentinel node (SN) biopsy.

METHODS

Sentinel node biopsy by subserosal or submucosal injection of indocyanine green (ICG) was performed in 241 patients with American Joint Committee on Cancer tumor, node, metastasis staging system, 7th edition, clinical T1 (n = 190) and T2 (n = 51) gastric cancer by two experienced surgeons. All nodes that stained green (green node, GN), representing SNs, were excised before gastrectomy and were sliced into 2-mm sections for intraoperative histological examinations with hematoxylin and eosin staining. The sliced GNs were also examined simultaneously by imprint cytology.

RESULTS

The GNs were detectable in 240 patients (3.8 ± 2.4 nodes per patient; range 1-17 nodes; median 3 nodes), and the success rate of detection was 99.6 % (240 of 241). Of 240 patients with a successful detection, 29 were found to have lymph node (LN) metastases; 16 were diagnosed with LN metastases in both GNs and non-GNs, 12 in GNs alone, and 1 in non-GNs alone. The false-negative rate based on the SN concept was 3.4 % (1 of 29). However, two patients with cT1 gastric cancer were diagnosed as intraoperative GN negative but were later confirmed as GN positive by histological examinations of paraffin sections. As an intraoperative diagnosis, the false-negative rate was 10.3 % (3 of 29).

CONCLUSIONS

Sentinel node biopsy using ICG could be performed intraoperatively within reasonable limits under certain conditions, such as multiplanes for detection, combination use of imprint cytology, and open surgery by experienced surgeons.

What is the problem in clinical application of sentinel node concept to gastric cancer surgery?

More than ten years have passed since the sentinel node (SN) concept for gastric cancer surgery was first discussed. Less invasive modified surgical approaches based on the SN concept have already been put into practice for malignant melanoma and breast cancer, however the SN concept is not yet placed in a standard position in gastric cancer surgery even after two multi-institutional prospective clinical trials, the Japan Clinical Oncology Group trial (JCOG0302) and the Japanese Society for Sentinel Node Navigation Surgery (SNNS) trial. What is the problem in the clinical application of the SN concept to gastric cancer surgery? There is no doubt that we need reliable indicator(s) to determine with certainty the absence of metastasis in the lymph nodes in order to avoid unnecessary lymphadenectomy. There are several matters of debate in performing the actual procedure, such as the type of tracer, the site of injection, how to detect and harvest, how to detect metastases of SNs, and learning period. These issues have to be addressed further to establish the most suitable procedure. Novel technologies such as indocyanine green (ICG) fluorescence imaging and one-step nucleic acid amplification (OSNA) may overcome the current difficulties. Once we know what the problems are and how to tackle them, we can pursue the goal.

Gastric adenocarcinoma surgery and adjuvant therapy

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

Precise pathologic examination decreases the false-negative rate of sentinel lymph node biopsy in gastric cancer

BACKGROUND

Gastric cancer has been identified as a target for sentinel lymph node (SLN) navigational surgery. Although accurate evaluation of SLNs is essential for applying the SLN concept to gastric cancer surgery, there is no standardized pathologic examination protocol for SLNs in gastric cancer.

METHODS

A total of 231 SLNs from 69 patients with cT1-2, N0 gastric cancer were prospectively examined in this study. During the operation, SLNs were sliced at 2-mm intervals, and frozen sections were analyzed by hematoxylin and eosin (HE) staining in 35 patients or HE staining with rapid immunohistochemistry (IHC) for pancytokeratin (CK) in 34 patients. HE staining and CK IHC were performed postoperatively on each remaining SLN. Non-SLNs were evaluated with 2 levels of HE slides and 1 CK IHC.

RESULTS

Of 35 patients, metastasis was identified in 10 patients by intraoperative HE staining, and in 12 patients by postoperative HE staining and CK IHC. Two patients had isolated tumor cells (ITCs) detectable by postoperative CK IHC; these patients had non-SLN metastasis. We enrolled another 34 patients and examined 147 SLNs by frozen HE and rapid IHC. In this cohort, 26 patients with negative SLNs by intraoperative examination did not have non-SLN metastasis even after deeper sectioning and CK IHC of non-SLNs (sensitivity, 100%; false negative value, 0%).

CONCLUSIONS

Our study indicated that precise and detailed intraoperative examination decreases the false-negative rate of SLN biopsy. ITCs in SLNs should not be overlooked, and rapid IHC can be helpful for detecting ITCs intraoperatively.

High FOXP3+ regulatory T-cell density in the sentinel lymph node is associated with downstream non-sentinel lymph-node metastasis in gastric cancer

Background:

We aimed to evaluate the immunologic nature of sentinel lymph nodes (SLNs) in gastric cancer patients and to determine whether it can predict non-SLN metastasis.

Methods:

Sentinel lymph node samples were collected from 64 gastric carcinoma patients who had undergone gastrectomy with SLN biopsy. One representative SLN sample was selected from each patient and was subjected to immunostaining for CD8, CD57, FOXP3, and DC-LAMP. The numbers of marker-positive cells in each sample were counted. The relationships between various immune cell densities and clinicopathologic parameters or metastasis status of SLNs and non-SLNs were sought.

Results:

High FOXP3+ Treg density of the SLN was found to be significantly associated with the presence of metastasis in either SLNs or non-SLNs. DC-LAMP+ cell density of the SLN was the highest at the isolated tumours cell level, and this decreased along with an increase in tumour metastasis in either SLNs or non-SLNs. Univariate and multivariate logistic regression models revealed that high FOXP3+ Treg density of the SLN was an independently significant predictor of non-SLN metastasis.

Conclusions:

This study is the first to indicate an important role of SLNs in metastatic dissemination of gastric cancer. Our findings suggest that Tregs could be a new therapeutic target for regulating the metastasis of gastric cancer.

Is the sentinel node biopsy clinically applicable for limited lymphadenectomy and modified gastric resection in gastric cancer? A meta-analysis of feasibility studies

BACKGROUND

Sentinel node biopsies (SNBs) have been clinically applied in melanoma and breast cancer for limited lymphadenectomy. However, the use of SNB remains controversial in gastric cancer due to unsatisfactory sensitivity and variability. This meta-analysis was performed to determine the sensitivity of SNB in gastric cancer and to identify factors that improve its sensitivity.

METHODS

Feasibility studies on SNB in gastric cancer were searched for from 2001 to 2009 in Pubmed, Cochrane, and Embase. Forty-six reports, which included 2,684 patients, were found. Estimated sensitivities, detection rates, and negative (NPV), and positive predictive values (PPV) were calculated using a random effects model. Inter-study heterogeneity, meta-regression, and subgroup analysis for sensitivity was performed.

RESULTS

The estimated sensitivity, detection rate, NPV, and PPV were 87.8%, 97.5%, 91.8%, and 38.0%, respectively, with significant inter-study heterogeneity (P < 0.0001). However, no significant contributor to heterogeneity was identified. By subgroup analysis, sensitivity was found to depend significantly on the number of SNs harvested.

CONCLUSIONS

SNB in gastric cancer is probably not clinically applicable for limited lymphadenectomy due its unsatisfactory sensitivity and heterogeneity between practicing surgeons. To improve sensitivity, more than four SNs should be harvested, and a tumor specific SNB method should be developed.

A novel insight of sentinel lymph node concept based on 1-3 positive nodes in patients with pT1-2 gastric cancer

Background

Sentinel node (SN) biopsy has been practiced in gastric cancer in recent years, and many studies focused on the distribution of solitary lymph node metastasis (SLM) to assess the pattern of SN. In fact, there is usually more than one SN existing in gastric cancer. The distribution of SNs needs to be further re-evaluated.

Methods

A total of 289 patients in pT1-2 stage with 1-3 positive nodes confined to same compartment were included in this study with informed consents. The primary lesion was solitary (≤ 5.0 cm in diameter) and D2 or D3 lymph node dissection had been performed. The location of metastatic lymph nodes was analyzed retrospectively.

Results

Most positive nodes occurred in N1 compartment, with frequency of 79.6% to 85.7% based on site of tumor. In the lower third of stomach, no. 6 was the most common metastatic site and no. 3 was the second; the order was reversed for SLM. With increasing depth of tumor invasion, a progressively augmented nodal involvement was shown. Nearly a half appeared transverse metastasis when the tumor located at the lesser or greater curvature. Among skip metastasis, no. 7, 8a, 9 and 11p were the most common metastatic sites and the prognosis was as similar as that of patients with N1 involved only.

Conclusions

The 1-3 positive nodes in the same compartment should be possible SNs, and most of which are restricted in N1 in pT1-2 gastric cancer. Transversal and 2 stations lymph node metastasis are common.

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

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

Sentinel lymph node biopsy in gastric cancer: possible applications and limits

AIMS

To explore the feasibility and accuracy of sentinel lymph node (SLN) biopsy in gastric cancer.

PATIENTS AND METHODS

Twenty-nine patients with clinical T1 and T2 N0 M0 gastric cancer less than 5 cm in diameter underwent SLN biopsy with the intraoperative Patent blue method. The procedure continued with radical gastrectomy and D2 lymphadenectomy. We investigated all technical aspects of the blue dye technique and determined the accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of the SLN technique.

RESULTS

SLNs were detected in 28 of 29 patients; the total number of excised SLNs was 45, with a median of two (range 1-3). Seventeen patients had metastatic SLN, with 21 lymph nodes retrieved. Twenty-two patients had SLNs located at the first level. Four patients had SLNs at the second level, one at the first and second levels, and one at the first and third levels. Five patients had false negative SLNs. The ability of SLN biopsy to predict the status of the other lymph nodes was summarised by an accuracy of 75%, a sensitivity of 75%, a specificity of 75%, a positive predictive value of 88%, and a negative predictive value of 55%.

CONCLUSIONS

Our study demonstrates that pick-up SLN biopsy in gastric cancer is technically feasible but has very low sensitivity. Regarding the utility of SLN navigation when attempting to detect the nodal basin, the high rate of false negative SLNs and lymph node level jumping warrant further studies with a large accrual before the method can be introduced into daily practice.

Sentinel node mapping with indocyanine green (ICG) and infrared ray detection in early gastric cancer: an accurate method that enables a limited lymphadenectomy

AIM

This study compares lymphatic mapping in early gastric cancer with ICG and infrared ray electronic endoscopy (IREE) to ICG alone. It examines the optimal method for intra-operative detection of metastases and shows long term follow up results.

METHODS

212 patients underwent the SN procedure with IREE and peritumoural ICG injection. Evaluated parameters were detection of sentinel nodes with IREE versus ICG alone, intra-operative detection rate of lymph node (LN) metastasis with node picking versus lymphatic basin dissection (LBD) and lymphatic drainage patterns.

RESULTS

34 patients had LN metastases. The SN identification rate and sensitivity for IREE versus ICG alone were 99.5 versus 85.8% and 97.0 versus 48.4% respectively. Intra-operative accuracy for detecting LN metastasis was 50% with node picking versus 92.3% with LBD. LN metastases were always in the SN basin. Lymphatic invasion and T-stage were risk factors for nodal metastases. Two patients showed recurrent disease. Both had a tumour with signet cell differentiation. One patient had a T3 tumour, the other patient had a tumour with a diameter of 85 mm.

CONCLUSION

The SN procedure with IREE can detect the SN and is better than ICG alone. LBD of the SN basin is required for accurate intra-operative diagnosis of metastases. LBD dissection based on IREE is a safe method of nodal dissection in patients with T1 or limited T2 tumours.