Assessment of lymph node micrometastasis in early gastric cancer in relation to sentinel nodes

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.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Occult Tumour Cells in Lymph Nodes from Gastric Cancer Patients: Should Isolated Tumour Cells Also Be Considered?

INTRODUCTION

Regional lymph node metastasis is an important prognostic factor for patients with gastric cancer. Occult tumour cells (OTCs), including either micrometastases (MMs) or isolated tumour cells (ITCs), may be a key factor in the development of cancer recurrence in pN0 patients.

AIMS

We aimed to determine the frequency and prognostic significance for disease recurrence of OTCs.

MATERIALS AND METHODS

This retrospective cohort study included all consecutive patients with pN0 gastric adenocarcinoma between January 2000 and December 2011 (n = 73). Immunohistochemistry using the pan-cytokeratin antibody AE1/AE3 was used to detect OTCs in 1257 isolated lymph nodes.

RESULTS

OTCs were identified in 30 patients (41%), including 20 cases with MMs (27%) and 10 cases with ITCs (14%). Disease recurrence and cancer-related death were observed in 24 (33%) and 20 patients (27%), respectively, and both were significantly associated with the detection of OTCs. A significant difference was also observed for the mean survival time between patients with OTCs and those without OTCs [100 vs 158 months (p = 0.015)]. The presence of OTCs was statistically significantly associated with the Lauren classification, tumour size and lymphatic permeation. Multivariate analyses revealed that only age, T stage and the presence of ITCs in lymph nodes were independent factors for recurrence. The presence of ITCs increased the risk for recurrence by 11.1-fold.

CONCLUSIONS

In a significant proportion of patients diagnosed as stage pN0, OTCs may be identified in lymph nodes if carefully searched for, which can negatively affect their prognosis. The presence of ITCs was found to be an independent factor for recurrence and after proper validation should be considered during lymph node assessment for prognosis definition.

[Micrometastasis in Gastric Cancer]

Although the incidence and mortality rate of gastric cancer have been steadily declining, gastric cancer is still the fourth most common cancer in the world and more than 50% of cases occur in Eastern Asia. In Korea, gastric cancer is the second most common cancer and third cause of cancer related death. The standard surgical procedure for resectable advanced gastric cancer is D2 lymphadenectomy with radical gastrectomy. Even though R0 resection was completed, recurrence is relatively common, and contributes to the limited survival of the patients in gastric cancer. As a clinically relevant factor for detection of the recurrence, the presence of isolating tumor cells has been introduced and it is so called as 'micrometastasis'. Numerous immunohistochemistry and molecular studies have shown that micrometastasis can be demonstrated not only in lymph nodes but also in such body compartments as the bone marrow, peritoneal cavity and blood. Herein, we review the current knowledge and evidence of the prognostic significance of micrometastasis in peritoneal, lymph node, bone marrow. Also, we discuss the current state of research on the circulating tumor cell in peripheral blood.

Sentinel lymph node navigation surgery for gastric cancer: Does it really benefit the patient?

Sentinel lymph node (SLN) navigation surgery is accepted as a standard treatment procedure for malignant melanoma and breast cancer. However, the benefit of reduced lymphadenectomy based on SLN examination remains unclear in cases of gastric cancer. Here, we review previous studies to determine whether SLN navigation surgery is beneficial for gastric cancer patients. Recently, a large-scale prospective study from the Japanese Society of Sentinel Node Navigation Surgery reported that the endoscopic dual tracer method, using a dye and radioisotope for SLN biopsy, was safe and effective when applied to cases of superficial and relatively small gastric cancers. SLN mapping with SLN basin dissection was preferred for early gastric cancer since it is minimally invasive. However, previous studies reported that limited gastrectomy and lymphadenectomy may not improve the patient’s postoperative quality of life (QOL). As a result, the benefit of SLN navigation surgery for gastric cancer patients, in terms of their QOL, is limited. Thus, endoscopic and laparoscopic limited gastrectomy combined with SLN navigation surgery has the potential to become the standard minimally invasive surgery in early gastric cancer.

Occult Tumor Cells in Lymph Nodes of Patients with Gastric Cancer: A Systematic Review on Their Prevalence and Predictive Role

BACKGROUND AND AIMS

The presence of lymph node (LN) metastasis is a key prognostic factor for gastric adenocarcinoma. However, even among patients without LN metastasis (N0), recurrence may occur. In some of these cases, occult tumor cells (OTC) are thought to play an important role. We aimed to determine the prevalence of OTC and its clinical relevance.

METHODS

We conducted a systematic review of studies in English published until September 2013 that addressed OTC prevalence and/or its clinical relevance. The studies were retrieved from the MEDLINE database.

RESULTS

We included 42 studies. The most frequently used methods for detecting OTC were immunohistochemical examination (IHC) and/or polymerase chain reaction (PCR) with a wide range of markers. Using IHC for OTC detection, in patients and in LN, the prevalence varied from 9 to 88% and 0.4 to 42%, respectively. With PCR, it ranged from 17 to 46% in patients, and from 3 to 33% in LN. In the studies assessing the predictive role of OTC in gastric cancer recurrence (n=24), 8 studies found no statistical association, while 18 concluded that OTC presence was associated with poorer prognosis. However, only 6 studies presented a significantly different 5-year survival rate between patients with and without LN micrometastasis.

CONCLUSIONS

OTC seems to occur in gastric cancer patients with a variable prevalence, depending on the definition, methods and setting. The majority of the retrieved studies (75%) evaluating the predictive role of OTC conclude that its presence is associated with a worse prognosis.

A new stage of sentinel node navigation surgery in early gastric cancer

Sentinel node (SN) navigation surgery is expected to realize organ- and function-preserving surgery with SN mapping, and has been applied in operations for breast cancer and melanoma. But there has been no definite evidence for the SN concept in gastric cancer. A prospective multicenter trial to confirm the SN concept for gastric cancer conducted by the Japan Society of Sentinel Node Navigation Surgery reported that the SN detection rate, sensitivity of positive SNs, and accuracy of nodal status are 97.5% (387/397), 93% (53/57), and 99% (383/387), respectively. A detailed analysis of the trial suggested that strictly the "lymphatic basin concept" rather than the "SN concept" was confirmed in early gastric cancer. The Japan Society of Sentinel Node Navigation Surgery started a new trial of function-preserving gastrectomy with lymphatic basin dissection (LBD) for early gastric cancer without metastasis in SNs on the basis of this promising outcome of the trial. It is supposed that LBD guarantees curability in SN navigation surgery for early gastric cancer. Full-thickness resection or endoscopic submucosal dissection in combination with laparoscopic LBD will soon be a new treatment option for early gastric cancer.

Clinical significance of molecular diagnosis for gastric cancer lymph node micrometastasis

Advances in molecular diagnostic tools have allowed the identification of lymph node micrometastasis (LNM), including isolated tumor cells, in cancer patients. While immunohistochemistry and reverse transcription-polymerase chain reaction have been used to identify LNM in patients with gastric cancer, the clinical significance of this finding remains unclear. Recently, minimally invasive treatments, such as endoscopic submucosal dissection and laparoscopic surgery, are widely performed to help improve postsurgical quality of life (QOL). However, it is important to maintain the balance between QOL and curability when making treatments decision for patients with gastric cancer. If minimally invasive surgery based on accurate intraoperative LNM diagnosis was established, it could be performed safely. Therefore, we reviewed the clinical significance of LNM detected by molecular techniques as an important target for treatment decision making with gastric cancer patients.

Meta-analysis of pylorus-preserving gastrectomy for middle-third early gastric cancer

BACKGROUND

Pylorus-preserving gastrectomy (PPG) has been performed to reduce postprandial symptoms for some early gastric cancer (EGC) cases. The aim of this study was to evaluate the possible advantages after PPG for middle-third EGC in comparison with distal gastrectomy.

MATERIALS AND METHODS

We searched Medline, Embase, and Science Citation Index Expanded for relevant studies. Statistical analyses were conducted to calculate the summary weighted mean differences (WMDs) and odds ratios (ORs) with corresponding 95% confidence intervals (95% CIs) using random-effects models.

RESULTS

We identified 15 nonrandomized controlled trials (16 studies) with 1774 patients, which consisted of 11 studies for conventional PPG (CPPG) versus conventional distal gastrectomy (CDG) and 5 studies for laparoscopy-assisted PPG (LAPPG) versus laparoscopy-assisted distal gastrectomy (LADG). Meta-analysis of CPPG versus CDG revealed that CPPG had the advantage of prevention of early dumping syndrome (OR=0.18; 95% CI 0.12, 0.27), gastritis (OR=0.19; 95% CI 0.07, 0.53), duodenal juice reflux (OR=0.20; 95% CI 0.06, 0.66), and regaining of weight (WMD=3.53; 95% CI 2.34, 4.72). However, the incidence of gastric stasis was higher in the CPPG group than in the CDG group (OR=1.70; 95% CI 1.13, 2.57). Meta-analysis of LAPPG versus LADG revealed that LAPPG shortened the operation time (WMD=-21.12; 95% CI -31.33, -10.90) and did not increase the occurrence of postoperative complication (OR=0.72; 95% CI 0.41, 1.27).

CONCLUSIONS

With the benefits of prevention of early dumping syndrome, duodenal juice reflux, gastritis, and regaining of weight, PPG can be an excellent option for middle-third EGC.

Clinical impact of the extent of lymph node micrometastasis in undifferentiated-type early gastric cancer

OBJECTIVE

Lymph node (LN) metastasis is one of the most important prognostic factors for undifferentiated-type early gastric cancer (EGC). The aim of this study was to examine expansion of micrometastasis in regional LNs to clarify the importance of lymphadenectomy for undifferentiated-type EGC.

METHODS

Clinicopathological features of 307 patients with undifferentiated-type EGC who underwent gastrectomy with lymphadenectomy between 1997 and 2010 at the Department of Surgical Oncology, Osaka City University, were retrospectively reviewed. Micrometastasis in LNs was detected by immunohistochemistry using anticytokeratin antibody.

RESULTS

The incidence of LN metastasis was 1.8% in patients with mucosal (pT1a) tumors and 17.3% in those with submucosal (pT1b) tumors. Multivariate analysis revealed that lymphatic invasion and tumor depth were independently related to LN metastasis. Micrometastasis was found in 41 (13.3%) patients. Twenty-two patients with pN0 had micrometastasis in the perigastric region. Micrometastasis had spread to the area along the left gastric or common hepatic artery in 12 patients. Patients with an upgraded stage by micrometastasis had significantly worse disease-free survival.

CONCLUSIONS

LN micrometastasis was observed beyond the perigastric LNs and correlated with poor outcomes in patients with undifferentiated-type EGC. These data underscore the importance of adequate lymphadenectomy for patients with undifferentiated-type EGC. © 2014 S. Karger AG, Basel.

Oncologic safety of pylorus-preserving gastrectomy in the aspect of micrometastasis in lymph nodes at stations 5 and 6

BACKGROUND

Pylorus-preserving gastrectomy (PPG) is a function-preserving gastrectomy for early gastric cancers (EGCs) that are preoperatively assessed as pN0 tumors and located in the middle portion of the stomach. In PPG, dissection of the lymph nodes at stations 5 and 6 is frequently incomplete, and this may be worrisome in terms of oncologic safety.

METHODS

We examined lymph nodes collected from stations 5 and 6 from 196 patients who had undergone conventional distal gastrectomy (CDG) for EGC located in the middle portion of the stomach and from 24 patients who had undergone PPG.

RESULTS

The average number of lymph nodes collected at station 5 was significantly lower with PPG than with CDG (0.08 vs. 1.32, respectively; P = 0.008). However, such a difference was not noted for station 6 nodes. The rate of macrometastasis was very low in all station 5 nodes (1 of 220, 0.45%) and station 6 nodes (1 of 220, 0.45%). Immunohistochemical analysis of cytokeratin in 109 cases of the CDG group and 21 cases of the PPG group showed that micrometastasis of single isolated tumor cell type was observed in only one station 6 lymph node of a patient who was initially diagnosed with pN0 EGC. There were no cases of micrometastasis in station 5 nodes.

CONCLUSIONS

The possibility of micrometastasis to station 5 and/or 6 lymph nodes may be negligible for EGC located in the middle portion of the stomach, and PPG thus might be the oncologically safe procedure when considering micrometastasis in remaining nodes in vivo at stations 5 and 6.

Lymph node micrometastasis in gastrointestinal tract cancer--a clinical aspect

Lymph node micrometastasis (LNM) can now be detected thanks to the development of various biological methods such as immunohistochemistry (IHC) and reverse transcription-polymerase chain reaction (RT-PCR). Although several reports have examined LNM in various carcinomas, including gastrointestinal (GI) cancer, the clinical significance of LNM remains controversial. Clinically, the presence of LNM is particularly important in patients without nodal metastasis on routine histological examination (pN0), because patients with pN0 but with LNM already in fact have metastatic potential. However, at present, several technical obstacles are impeding the detection of LNM using methods such as IHC or RT-PCR. Accurate evaluation should be carried out using the same antibody or primer and the same technique in a large number of patients. The clinical importance of the difference between LNM and isolated tumor cells (≤0.2 mm in diameter) will also be gradually clarified. It is important that the results of basic studies on LNM are prospectively introduced into the clinical field. Rapid diagnosis of LNM using IHC and RT-PCR during surgery would be clinically useful. Currently, minimally invasive treatments such as endoscopic submucosal dissection and laparoscopic surgery with individualized lymphadenectomy are increasingly being performed. Accurate diagnosis of LNM would clarify issues of curability and safety when performing such treatments. In the near future, individualized lymphadenectomy will develop based on the establishment of rapid, accurate diagnosis of LNM.

Intraoperative diagnosis of lymph node metastasis by transcription-reverse transcription concerted reaction assay in gastric cancer

BACKGROUND

Increasing evidence has been accumulated to substantiate the clinical usefulness of quantitative evaluation of gene expression. This study was undertaken to assess diagnosis of metastasis in dissected lymph nodes through quantitative evaluation of the expression of carcinoembryonic antigen mRNA (CEA mRNA) by a rapid, simple transcription-reverse transcription concerted reaction (TRC) assay using dissected lymph node washings.

METHODS

A total of 110 dissected lymph nodes from 40 patients undergoing surgery for gastric cancer were studied. Each dissected lymph node was cut crosswise and washed with physiological saline. The washings were assayed for CEA mRNA and the assay results were assessed in comparison with the pathological diagnosis [hematoxylin and eosin (H&E) staining]. All lymph nodes were also subjected to immunostaining for cytokeratin (CK staining) and assessed comparatively.

RESULTS

By H&E staining, 29 lymph nodes were found to be positive and 81 to be negative for metastasis. By TRC assay, 38 lymph nodes were found to be positive and 72 to be negative. According to the results of CK staining, there were 37 metastasis-positive lymph nodes and 73 negative nodes. The sensitivity and specificity of H&E staining relative to those of CK staining were 78.4 and 100 %, respectively, while the sensitivity and specificity of TRC assay relative to those of CK staining were 91.9 and 94.5 %, respectively.

CONCLUSIONS

The TRC assay method using lymph node washings is a rapid, simple genetic diagnosis with greater sensitivity than conventional diagnosis by H&E staining of permanent specimens, and enables conservation of lymph nodes in toto as permanent specimens. This TRC method would enable rapid diagnosis even in town hospitals where no pathologist is ordinarily stationed, and is considered to contribute to the clinical application of the sentinel node theory of gastric cancer treatment.

Comparison of immunohistology using pan-CK and EMA in the diagnosis of lymph node metastasis of gastric cancer, particularly micrometastasis and isolated tumor cells

The aim of this study was to identify a suitable method for detecting lymph node metastasis of gastric cancer (GCA) by hematoxylin and eosin (HE) and immunohistochemical (IHC) staining. We investigated lymph node metastasis using pan-cytokeratin (CK) and epithelial membrane antigen (EMA) IHC staining in a total of 1,422 lymph nodes from 100 patients who underwent radical gastrectomy between 2007 and 2009. Of 700 intestinal and 722 diffuse type GCA lymph nodes, the metastasis rates were significantly different when using conventional HE staining only or HE supplemented with IHC (P<0.01). The metastasis rate of the intestinal type was 31.71% using HE staining, 35.71% with HE and pan-CK, 35.57% with HE and EMA and 35.71% with combination examinations of all three. The false-positive rate was zero with pan-CK, 12.67% with EMA and 18.57% with all three. The metastasis rate of the diffuse type was 27.70% using HE staining, 36.01% with HE and pan-CK, 35.04% with HE and EMA and 36.01% with all three. The false-positive rate was zero with pan-CK, 7.58% with EMA and 11.86% with all three. For both types, the true-positive and -negative rates of pan-CK were higher than those of EMA. IHC staining is unnecessary if lymph node metastasis is detected in HE staining. If HE staining does not reveal metastasis, pan-CK staining should be performed for further diagnosis.

What is the accuracy of sentinel lymph node biopsy for gastric cancer? A systematic review

BACKGROUND

In gastric cancer, the utility of sentinel lymph node (SLN) biopsy has not been established. SLN may be a good predictor of the pathological status of other lymph nodes and thus the necessity for more extensive surgery or lymph node dissection. We aimed to identify and synthesize findings on the performance of SLN biopsies in gastric cancer.

METHODS

Electronic literature searches were conducted using Medline, EMBASE, and the Cochrane Central Register of Controlled Trials from 1998 to 2009. Titles and abstracts were independently rated for relevance by a minimum of two reviewers. Techniques, detection rates, accuracy, sensitivity, specificity, and false-negative rates (FNRs) were analyzed. Analysis was performed based on the FNR.

RESULTS

Twenty-six articles met our inclusion criteria. SLN detection using the dye method (DM) was reviewed in 18 studies, the radiocolloid method (RM) was used in 12 studies, and both dye and radiocolloid methods (DUAL) were used in 5 studies. The DM had an overall calculated FNR of 34.7% (95% confidence interval [CI] 21.2, 48.1). The RM had an overall calculated FNR of 18.5% (95% CI 9.1, 28.0). DUAL had an overall calculated FNR of 13.1% (95% CI -0.9, 27.2).

CONCLUSION

Application of the SLN technique may be practical for early gastric cancer. The use of DUAL for identifying SLN may yield a lower FNR than either method alone, although statistical significance was not met.

Clinical significance of lymph node micrometastasis in gastric cancer

Recently, the existence of lymph node micrometastasis (LNM), including isolated tumor cells, has been focused on during the development of molecular diagnostic tools for lymph node metastasis in various malignant neoplasms. In particular, immunohistochemistry and reverse transcription-polymerase chain reaction have been reported to be available for the detection of LNM in gastric cancer. However, at present, the clinical significance of LNM remains unclear in patients with gastric cancer. Therefore, we cannot strategically make light of this issue in clinical management. Currently, minimally invasive treatments, such as endoscopic submucosal dissection and laparoscopic surgery with personalized lymphadenectomy, are widely performed in consideration of postsurgical quality of life (QOL). However, it is important to maintain the balance between QOL and curability when selecting surgical treatments for patients with gastric cancer. If minimally invasive surgery based on LNM status was established for patients with early gastric cancer, it could be performed safely. We reviewed the clinical significance of LNM as an important strategic target in patients with gastric cancer.

Lymph node, peritoneal and bone marrow micrometastases in gastric cancer: Their clinical significance

The 7th TNM classification clearly states that micrometastases detected by morphological techniques (HE stain and immunohistochemistry) should always be reported and calculated in the staging of the disease (pN1mi or M1), while patients in whom micrometastases are detected by non-morphological techniques (e.g., flow cytometry, reverse-transcriptase polymerase chain reaction) should still be classified as N0 or M0. In gastric cancer patients, micrometastases have been detected in lymph nodes, the peritoneal cavity and bone marrow. However, the clinical implications and/or their prognostic significance are still a matter of debate. Current literature suggests that lymph node micrometastases should be encountered for the loco-regional staging of the disease, while skip lymph node micrometastases should also be encountered in the total number of infiltrated lymph nodes. Peritoneal fluid cytology examination should be obligatorily performed in pT3 or pT4 tumors. A positive cytology classifies gastric cancer patients as stage IV. Although a curative resection is not precluded, these patients face an overall dismal prognosis. Whether patients with a positive cytology should be treated similarly to patients with macroscopic peritoneal recurrence should be evaluated further. Gastric cancer cells are detected with high incidence in the bone marrow. However, the published results make comparison of data between groups almost impossible due to severe methodological problems. If these methodological problems are overcome in the future, specific target therapies may be designed for specific groups of patients.

Molecular detection of sentinel node micrometastases in patients with clinical N0 gastric carcinoma with real-time multiplex reverse transcription-polymerase chain reaction assay

PURPOSE

Described is a novel real-time multiplex reverse transcription-polymerase chain reaction (RT-PCR) assay suitable for intraoperative detection of micrometastasis (MM) in sentinel nodes (SNs) dissected from patients with clinical N0 (cN0) gastric carcinoma.

METHODS

One hundred three patients with gastric cancer, who were preoperatively diagnosed with cN0 and clinical T1 or T2, were enrolled. The patients underwent SN mapping followed by standard radical gastrectomy with lymph node dissection. In addition to all SNs, non-SNs (NSNs) within the SN lymphatic basin and NSN from a different lymphatic basin were randomly sampled. All SNs and NSNs were examined by routine histologic diagnosis and RT-PCR for the expression of cytokeratin (CK) 19, CK20, and carcinoembryonic antigen (CEA).

RESULTS

The RT-PCR assay and histologic examination were performed in 512 SNs and 299 NSNs from 103 patients. Pathologic l lymph node metastasis was revealed in 13 (12.6%) of 103 patients. All metastatic lymph nodes were identified within SNs. SNs of these 13 patients had positive findings on RT-PCR. Twenty-eight (27.2%) of 103 patients had negative histopathology but positive findings on RT-PCR. In 7 patients (6.8%), SNs were negative but NSNs were positive on RT-PCR. RT-PCR-positive NSNs were present in the same station as corresponding SNs in 3 of these 7 patients and in the same basin as SNs in 4 patients.

CONCLUSIONS

The real-time multiplex RT-PCR assay is a useful tool for the detection of MM in SNs and NSNs in patients with gastric cancer.

Treatment strategy for early gastric cancer

Gastric cancer ranks the second leading cause of cancer-specific mortality worldwide. With a poor prognosis, 5-year survival rate of gastric cancer is less than 20%-25% in the USA, Europe, and China [1]. However, early gastric cancer(EGC) offers an excellent (over 90%) chance of cure based on surgical resection [2]. As the increasing detection of EGC, more treatment options have been developed both curatively and minimally invasively to maintain a good quality of life(QOL). One of the advanced therapeutic techniques is endoscopic dissection. Improvements in surgical treatment include minimizing lymph node dissection, reconstruction methods, laparoscopy-assisted surgery, and sentinel node navigation surgery(SNNS) [3]. With technological advances, even Natural Orifice Transluminal Endoscopy Surgery (NOTES) and robotic surgery are expected to represent the next revolution [4]. However, there still remains much dispute among these treatments, which arouses further clinical trials to verify. Update of the treatments, controversial indications, prognosis and current strategies for EGC are discussed in this review.

The possibility of performing a limited resection and a lymphadenectomy for proximal gastric carcinoma based on sentinel node navigation

PURPOSE

This study examined the possibility of performing a limited resection and a lymphadenectomy with sentinel node navigation surgery (SNNS) for the treatment of proximal gastric carcinoma.

METHODS

Thirty patients with cT1N0 (n = 23) and cT2N0 (n = 7) proximal gastric carcinoma that was located primarily in the U area (the upper third of the stomach) were enrolled. indocyanine green (ICG; 0.5 ml) was injected endoscopically into the submucosa of the four quadrants encompassing the cancer. Twenty minutes after injection, infrared ray electronic endoscopy (IREE) was used to identify the lymph nodes that were stained with ICG (sentinel nodes, SNs) around the serosa and surrounding fat tissue.

RESULTS

One hundred percent of the SNs were identified with our SNNS method. The most common location of SNs was No. 3 (T1: 78%, T2: 100%). The main route of lymphatic drainage was from No. 1 or No. 3 to No. 7 (T1: 95%, T2: 100%). In T1 cancer, Indocyanine green was not distributed to the right gastric area, and no patients had SNs in No. 5 or No. 8a. Four cT2 cancer patients had lymph node metastases, all of which were SNs. There were no cases of postoperative metastasis or recurrence.

CONCLUSIONS

For the cT1 proximal gastric carcinoma patients, limited dissection of the ICG tracer-positive lymphatic areas alone by SNNS using IREE may be acceptable. The main lymphatic drainage route of proximal gastric carcinoma is the left gastric artery area (Nos. 1, 3, and No. 7) and dissection of this area is important.

Routine modified D2 lymphadenectomy performance in pT1-T2N0 gastric cancer

AIM: To evaluate routine modified D2 lymphadenectomy in gastric cancer, based on immunohistochemically detected skip micrometastases in level II lymph nodes.

METHODS: Among 95 gastric cancer patients who were routinely submitted to curative modified D2 lymphadenectomy, from January 2004 to December 2008, 32 were classified as pN0. All level I lymph nodes of these 32 patients were submitted to immunohistochemistry for micrometastases detection. Patients in whom micrometastases were detected in the level I lymph node stations (n = 4) were excluded from further analysis. The level II lymph nodes of the remaining 28 patients were studied immunohistochemically for micrometastases detection and constitute the material of the present study.

RESULTS: Skip micrometastases in the level II lymph nodes were detected in 14% (4 out of 28) of the patients. The incidence was further increased to 17% (4 out of 24) in the subgroup of T1-2 gastric cancer patients. All micrometastases were detected in the No. 7 lymph node station. Thus, the disease was upstaged from stage IA to IB in one patient and from stage IB to II in three patients.

CONCLUSION: In gastric cancer, true R0 resection may not be achieved without modified D2 lymphadenectomy. Until D2+/D3 lymphadenectomy becomes standard, modified D2 lymphadenectomy should be performed routinely.

Limited gastrectomy with dissection of sentinel node stations for early gastric cancer with negative sentinel node biopsy

OBJECTIVE

To evaluate the early results of sentinel node (SN)-navigated limited surgery for early gastric cancer.

SUMMARY BACKGROUND DATA

False-negative results of SN biopsy cannot be ignored in gastric cancer surgery. Previous studies suggest that dissection of lymph node stations where SNs belong (SN stations) may minimize the possibility of leaving metastasis behind in SN-navigated surgery.

METHODS

Patients with T1N0M0 gastric cancer <4 cm were informed about the SN-navigated limited surgery from 2003 to 2008. SNs were identified using radioisotope and dye methods. When the SN biopsy by frozen section was negative, limited gastrectomy with dissection of SN stations was performed. Patients with SN stations limited to either the lesser or greater curvature underwent a wedge resection unless it would cause a strong deformity of the stomach. A sleeve gastrectomy was performed in other cases.

RESULTS

Six of the 60 enrolled patients chose a standard gastrectomy. Sixteen patients were excluded after laparotomy due to a T2-T3 tumor or tumor location. Three patients with positive SN biopsy underwent D2 gastrectomy, and 35 with negative SN biopsy underwent limited gastrectomy with dissection of SN stations; wedge resection in 8 and sleeve gastrectomy in 27. There were no operative mortalities or morbidities. All patients undergoing the limited surgery had no lymph node metastasis by postoperative pathology, and survived without any recurrence. The average area of the resected stomach for limited surgery was significantly smaller than that for standard procedures (92 +/- 50 vs. 189 +/- 64 cm, P < 0.001).

CONCLUSIONS

SN-navigated limited gastrectomy with dissection of SN stations for T1N0M0 gastric cancer was considered safe and acceptable although long-term follow-up is mandatory.

Methylene blue-assisted lymph node dissection in combination with ex vivo sentinel lymph node mapping in gastric cancer

AIMS

Lymph node (LN) stage is still the strongest prognostic marker in potentially curable gastric cancer. Accuracy of histopathological lymph node assessment depends on the number of investigated LNs and detection rate of metastases and micrometastases. The aim was to perform a feasibility study employing intra-arterial methylene blue injection - a novel method to improve LN harvest - and ex vivo sentinel LN mapping.

METHODS AND RESULTS

A total of 33 cases were enrolled, including 14 retrospective cases that served as a control group. The methylene group showed a highly significant improved mean LN harvest compared with unstained cases, with 38 +/- 14 versus 21 +/- 10 LNs (P < 0.001), respectively. The detection rate of ex vivo sentinel mapping was 88%. No skip metastases occurred.

CONCLUSION

Both techniques have the potential to improve the accuracy of histopathological LN staging and can be combined successfully.

Increased risk of lymph node metastasis in mucosal gastric cancer with extra indication for endoscopic mucosal resection

BACKGROUND

Selected cases of clinical mucosal gastric cancer can be treated endoscopically. But mucosal gastric cancer, which has a higher incidence of lymph node metastasis, should be treated by gastrectomy with lymph node dissection. Laparoscopy-assisted gastrectomy is usually indicated for the surgical treatment of mucosal gastric cancer.

STUDY DESIGN

From April 2005 to December 2007, 148 consecutive patients with clinical mucosal gastric cancer who underwent laparoscopy-assisted gastrectomy were investigated to clarify the clinicopathologic findings in this patient group.

RESULTS

Of the patients who underwent gastrectomy, 93 (63%) had tumors>20 mm in diameter and 92 (62%) had undifferentiated cancer. The frequency of lymph node metastasis was 8% (12 patients). One patient had second-compartment lymph node metastasis (station 8a). In patients with lymph node metastasis, 11 (92%) had an ulcer scar and 11 (92%) had undifferentiated tumors. None of the patients met the criteria for extended endoscopic submucosal dissection.

CONCLUSIONS

The incidence of lymph node metastasis in patients with mucosal gastric cancer in whom gastrectomy is indicated is higher than reported previously. More careful consideration is needed for the possibility of lymph node metastasis in this era of endoscopic submucosal dissection.

Prognostic significance of occult lymph node micrometastasis in gastric cancer: a histochemical and immunohistochemical study based on 1997 UICC TNM and 1998 JGCA classifications

BACKGROUND: Micrometastasis is a single or a cluster of malignant cells inside the lymph node that are not detected by routine histopathological sections. Micrometastasis is related to poorer prognosis in many gastric cancer studies the real significance of these cells is still controversial. AIM: To evaluate if lymph node micrometastasis is a significant independent prognostic factor and important risk factor for recurrence in gastric cancer. METHODS: A total of 1290 lymph nodes from 28 patients with gastric cancer, since 1998 until 2003, treated by radical resection (D2 and modified D3 lymphadenectomies) were studied. Three sections per lymph node were stained by Hematoxilin-Eosin, histochemical (AB-PAS) and immunohistochemical (AE1-AE3) techniques. Kaplan-Meier's survival curves and Log-rank/Cox tests were used in order to compares lymph node micrometastasis positivity, depth (pT) and location of tumor in gastric wall, histologic type, lymphatic, vascular and perineural invasion, lymph node status (pN) and stage. RESULTS: There were worse prognosis and recurrence in patients with positive lymph node micrometastasis related to vascular and perineural invasions, advanced lymph node status and advanced stages. CONCLUSION: Lymph node micrometastasis seems to be a significant independent prognostic factor and important risk factor for recurrence in gastric cancer, in a context of radical D2 lymphadenectomy

Detection of sentinel and non-sentinel lymph node micrometastases by complete serial sectioning and immunohistochemical analysis for gastric cancer

BACKGROUND

We investigated the presence and distribution of the sentinel and the non-sentinel node micrometastases using complete serial sectioning and immunohistochemical staining (IHC), to inspect whether lymph node micrometastases spread to the sentinel lymph nodes first.

METHODS

A total of 35 patients, who underwent gastrectomy with a sentinel lymph node biopsy for gastric cancer, were enrolled in this study. Total of 1028 lymph nodes of 35 patients having gastric cancer without metastasis of lymph node by permanent section with hematoxylin and eosin staining (H&E) were selected. There were 252 sentinel nodes and the other 776 were non-sentinel nodes. All nodes were sectioned serially and stained alternately with H&E and IHC. Lymph node micrometastases was defined as proving to be positive first either the IHC or the complete serial sectioning.

RESULTS

Micrometastases were detected in 4 (11%) of the 35 patients, 6 (0.58%) of 1028 nodes. Of these 4 patients, 3 had micrometastases exclusively in sentinel nodes, and the other had micrometastasis in both sentinel and non-sentinel nodes. There was no patient who had the micrometastases only in non-sentinel nodes.

CONCLUSION

These results support the concept that lymph node micrometastasis of gastric cancer spreads first to sentinel nodes.

Sentinel lymph node biopsy for gastrointestinal cancers

Sentinel lymph node biopsy (SLNB) in gastrointestinal-(GI)-tract cancer is not yet of clinical relevance. Nevertheless, the results in the upper GI-tract promise to be helpful to individualize the indication for surgical therapy. SLNB in colon cancer still fails to show high validity to predict the nodal status, but may be helpful to clarify the prognostic role of micrometastases/isolated tumor cells. In anal cancer SLNB is able to guide the indication for groin irradiation.

Distribution of solitary lymph nodes in primary gastric cancer: A retrospective study and clinical implications

AIM: To investigate the distribution pathway of metastatic lymph nodes in gastric carcinoma as a foundation for rational lymphadenectomy.

METHODS: We investigated 173 cases with solitary or single station metastatic lymph nodes (LN) from among 2476 gastric carcinoma patients. The location of metastatic LN, histological type and growth patterns were analyzed retrospectively.

RESULTS: Of 88 solitary node metastases cases, 65 were limited to perigastric nodes (N₁), while 23 showed skipping metastasis. Among 8 tumors in the upper third stomach, 3 involved right paracardial LN (station number: No.1), and one in the greater curvature was found in No.1. In the 28 middle third stomach tumors, 10 were found in LN of the lesser curvature (No.3) and 6 in LN of the left gastric artery (No.7); 5 of the 20 cases on the lesser curvature spread to No.7, while 2 of the 8 on the greater curvature metastasized to LN of the spleen hilum (No.10). Of 52 lower third stomach tumors, 13 involved in No.3 and 19 were detected in inferior pyloric LN (No.6); 9 of the 29 cases along the lesser curvature were involved in No.6.

CONCLUSION: Transversal and skipping metastases of sentinel lymph nodes (SLN) are notable, and rational lymphadenectomy should, therefore, be performed.

Validity of modified gastrectomy combined with sentinel node navigation surgery for early gastric cancer

BACKGROUND

The present study examined the clinical validity of modified gastrectomy for early gastric cancer, in terms of the results of sentinel node navigation surgery (SNNS), using infrared ray electronic endoscopy (IREE) plus indocyanine green (ICG) staining.

METHODS

One-hundred and sixty-one patients with fT1N0 gastric cancer were enrolled in the study. ICG (0.5 ml, 5 mg/ml) was injected endoscopically into four quadrants of the submucosa surrounding the cancer. Twenty minutes after the injection, sentinel lymph nodes (SNs) stained with ICG were observed intraperitoneally around the serosa and surrounding fat tissue. IREE was used to illuminate regional lymph nodes from the serosal side.

RESULTS

Group 2 lymph nodes were judged as SNs in 52 patients (32%). The most common locations of the SNs were stations No. 7 in each of the upper-, middle-, and lower-thirds of the stomach. In two patients, lymph node metastasis was positive. One of these patients, with cancer in the middle one-third of the stomach, had SNs in stations No. 3, 4sb, 4d, 7, and No. 11p, and had metastatic lymph nodes in No. 3 and No. 7 (all SNs). The other patient, with cancer in the lower one-third of the stomach, had SNs in No. 1, 3, 4d, and 6, and had a metastatic lymph node in No. 4d (SN). Skip metastasis was not observed in this study, and metastatic lymph nodes were judged to have been dissected by the D1+a procedure.

CONCLUSION

For T1N0 gastric cancer, modified gastrectomy (D1+a dissection) combined with SNNS is suitable; however, for those whose Group 2 lymph nodes are judged to be SNs, additional dissection of lymphatic basins detected by SNNS should be performed to confirm the absence of lymph node metastasis.