Endoscopic resection of early gastric cancer: current status and new approaches

Effect of NETs/COX-2 pathway on immune microenvironment and metastasis in gastric cancer

Background

Neutrophil extracellular traps (NETs) are crucial in the progression of several cancers. The formation of NETs is closely related to reactive oxygen species (ROS), and the granule proteins involved in nucleosome depolymerization under the action of ROS together with the loosened DNA compose the basic structure of NETs. This study aims to investigate the specific mechanisms of NETs promoting gastric cancer metastasis in order to perfect the existing immunotherapy strategies.

Methods

In this study, the cells and tumor tissues of gastric cancer were detected by immunological experiments, real-time polymerase chain reaction and cytology experiments. Besides, bioinformatics analysis was used to analyze the correlation between cyclooxygenase-2 (COX-2) and the immune microenvironment of gastric cancer, as well as its effect on immunotherapy.

Results

Examination of clinical specimens showed that NETs were deposited in tumor tissues of patients with gastric cancer and their expression was significantly correlated with tumor staging. Bioinformatics analysis showed that COX-2 was involved in gastric cancer progression and was associated with immune cell infiltration as well as immunotherapy. In vitro experiments, we demonstrated that NETs could activate COX-2 through Toll-like receptor 2 (TLR2) and thus enhance the metastatic ability of gastric cancer cells. In addition, in a liver metastasis model of nude mice we also demonstrated the critical role of NETs and COX-2 in the distant metastasis of gastric cancer.

Conclusion

NETs can promote gastric cancer metastasis by initiating COX-2 through TLR2, and COX-2 may become a target for gastric cancer immunotherapy.

Application of Hemocoagulase Bothrops Atrox in the submucosal injection for endoscopic submucosal dissection: a preliminary trial

OBJECTIVE

This study aimed to evaluate the efficacy and safety of using Hemocoagulase Bothrops Atrox in the submucosal injection solution for endoscopic submucosal dissection (ESD).

METHODS

A total of 120 patients with superficial neoplastic lesions of the esophagus, stomach, and colon receiving ESD were randomly divided into two groups: The epinephrine group used epinephrine-containing submucosal fluid cushion for ESD, while the hemocoagulase group used Hemocoagulase Bothrops Atrox-containing submucosal fluid cushion for ESD. The preoperative, intraoperative, and postoperative clinical parameters and postoperative adverse events of the two groups were recorded, and comparative analysis within and between groups was performed.

RESULTS

There was no significant difference in the demographic and clinical characteristics between the hemocoagulase and epinephrine group (all P > 0.05). ESD surgery was completed in all patients. The hemocoagulase group had significantly shorter surgery time (P = 0.003) and less number of intraoperative bleeding (P = 0.010) than the epinephrine group. However, there was no significant difference in the incidences of postoperative delayed hemorrhage, and adverse events between the two groups (all P > 0.05). Multivariate linear regression demonstrated that the epinephrine group had significantly more number of intraoperative bleeding (B: 0.98, 95% confidence interval: 0.04-1.93) as compared with the hemocoagulase group.

CONCLUSION

Compared with epinephrine, using Hemocoagulase Bothrops Atrox in the submucosal injection for ESD surgery can significantly reduce the number of intraoperative bleeding, shorten the operation time, and did not elevate the incidence of adverse events.

B7 homologue 3 as a prognostic biomarker and potential therapeutic target in gastrointestinal tumors

The most common digestive system (DS) cancers, including tumors of the gastrointestinal tract (GIT) such as colorectal cancer (CRC), gastric cancer (GC) and esophageal cancer (EC) as well as tumors of DS accessory organs such as pancreatic and liver cancer, are responsible for more than one-third of all cancer-related deaths worldwide, despite the progress that has been achieved in anticancer therapy. Due to these limitations in treatment strategies, oncological research has taken outstanding steps towards a better understanding of cancer cell biological complexity and heterogeneity. These studies led to new molecular target-driven therapeutic approaches. Different in vivo and in vitro studies have revealed significant expression of B7 homologue 3 (B7-H3) among the most common cancers of the GIT, including CRC, GC, and EC, whereas B7-H3 expression in normal healthy tissue of these organs was shown to be absent or minimal. This molecule is able to influence the biological behavior of GIT tumors through the various immunological and nonimmunological molecular mechanisms, and some of them are shown to be the result of B7-H3-related induction of signal transduction pathways, such as Janus kinase 2/signal transducer and activator of transcription 3, phosphatidylinositol 3-kinase/protein kinase B, extracellular signal-regulated kinase, and nuclear factor-κB. B7-H3 exerts an important role in progression, metastasis and resistance to anticancer therapy in these tumors. In addition, the results of many studies suggest that B7-H3 stimulates immune evasion in GIT tumors by suppressing antitumor immune response. Accordingly, it was observed that experimental depletion or inhibition of B7-H3 in gastrointestinal cancers improved antitumor immune response, impaired tumor progression, invasion, angiogenesis, and metastasis and decreased resistance to anticancer therapy. Finally, the high expression of B7-H3 in most common cancers of the GIT was shown to be associated with poor prognosis. In this review, we summarize the established data from different GIT cancer-related studies and suggest that the B7-H3 molecule could be a promising prognostic biomarker and therapeutic target for anticancer immunotherapy in these tumors.

Association between mucin phenotype and lesion border detection using acetic acid-indigo carmine chromoendoscopy in early gastric cancers

BACKGROUND

For successful treatment of early gastric cancers (EGCs), it is crucial to define the horizontal border of the lesion with high accuracy. Acetic acid-indigo carmine (AI) chromoendoscopy has been used to determine the horizontal border in EGCs, but this technique is less potent in certain situations. Mucin phenotype in gastric cancers refers to biological differences in precursor lesions and differences in histopathologic findings, and it might affect AI chromoendoscopy findings. We aimed to investigate the association between mucin phenotype and AI chromoendoscopy findings in EGCs.

METHODS

We prospectively evaluated 126 lesions in 126 patients with endoscopically diagnosed EGCs. Conventional endoscopy and AI chromoendoscopy findings of these lesions before treatment were prospectively analyzed. The border distinction between the lesion and surrounding mucosa was classified as distinct or indistinct on conventional endoscopy and AI chromoendoscopy, respectively. Mucin phenotypes were classified as gastric, intestinal, gastrointestinal, or null type by immunohistochemistry.

RESULTS

The lesion borders were distinct in 46.8% (59/126) of the lesions assessed using conventional endoscopy and in 73.0% (92/126) of those assessed with AI chromoendoscopy (p < 0.001). The border distinction rate of differentiated-type cancers on AI chromoendoscopy was significantly higher than that on conventional endoscopy (66/71 [93.0%] vs. 34/71 [47.9%], p < 0.001), but the border distinction rate of undifferentiated-type cancers on AI chromoendoscopy was not different from that on conventional endoscopy (26/55 [47.3%] vs. 25/55 [45.5%], p = 0.848). Compared with conventional endoscopy, AI chromoendoscopy identified borders in a significantly higher percentage of gastric, intestinal, and gastrointestinal mucin types; however, there was no difference in AI chromoendoscopy findings according to the mucin phenotype (p = 0.271).

CONCLUSION

AI chromoendoscopy was effective in horizontal border delineation in differentiated-type EGCs, but not in undifferentiated-type EGCs. Mucin phenotype had no effect on border distinction using AI chromoendoscopy.

[Pneumothorax Following Gastric Endoscopic Mucosal Resection]

An endoscopic mucosal resection (EMR) is used widely as an alternative treatment to a surgical resection for early gastric neoplastic lesions. Among the unusual complications of gastric EMR, perforation is usually manifested as a pneumoperitoneum. This paper reports a patient with a left-side pneumothorax without pneumoperitoneum as a complication of gastric EMR. The patient developed a left side pneumothorax after gastric EMR in the gastric fundus and recovered without further complications after conservative treatment, including endoscopic clipping.

Identification of a Novel Prognostic Signature for Gastric Cancer Based on Multiple Level Integration and Global Network Optimization

Gastric Cancer (GC) is a common cancer worldwide with a high morbidity and mortality rate in Asia. Many prognostic signatures from genes and non-coding RNA (ncRNA) levels have been identified by high-throughput expression profiling for GC. To date, there have been no reports on integrated optimization analysis based on the GC global lncRNA-miRNA-mRNA network and the prognostic mechanism has not been studied. In the present work, a Gastric Cancer specific lncRNA-miRNA-mRNA regulatory network (GCsLMM) was constructed based on the ceRNA hypothesis by combining miRNA-target interactions and data on the expression of GC. To mine for novel prognostic signatures associated with GC, we performed topological analysis, a random walk with restart algorithm, in the GCsLMM from three levels, miRNA-, mRNA-, and lncRNA-levels. We further obtained candidate prognostic signatures by calculating the integrated score and analyzed the robustness of these signatures by combination strategy. The biological roles of key candidate signatures were also explored. Finally, we targeted the PHF10 gene and analyzed the expression patterns of PHF10 in independent datasets. The findings of this study will improve our understanding of the competing endogenous RNA (ceRNA) regulatory mechanisms and further facilitate the discovery of novel prognostic biomarkers for GC clinical guidelines.

TLRs as a Promise Target Along With Immune Checkpoint Against Gastric Cancer

Gastric cancer (GC) is one of the most common cancers in the world, and the incidence of gastric cancer in Asia appears to increase in recent years. Although there is a lot of improvement in treatment approaches, the prognosis of GC is poor. So it is urgent to search for a novel and more effective treatment to improve the survival rate of patients. Both innate immunity and adaptive immunity are important in cancer. In the innate immune system, pattern recognition receptors (PRRs) activate immune responses by recognizing pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). Toll-like receptors (TLRs) are a class of pattern recognition receptors (PRRs). Many studies have reported that TLRs are involved in the occurrence, development, and treatment of GC. Therefore, TLRs are potential targets for immunotherapy to gastric cancer. However, gastric cancer is a heterogeneous disorder, and TLRs function in GC is complex. TLRs agonists can be potentially used not only as therapeutic agents to treat gastric cancer but also as adjuvants in conjunction with other immunotherapies. They might provide a promising new target for GC treatment. In the review, we sort out the mechanism of TLRs involved in tumor immunity and summarize the current progress in TLRs-based therapeutic approaches and other immunotherapies in the treatment of GC.

Novel molecular targets in gastric adenocarcinoma

Gastric adenocarcinoma (GAC) is the third leading cause of cancer-related death worldwide. A high mortality rate and resistance to treatment protocols due to a heterogeneous molecular pathogenesis has made discovering the key etiologic molecular alterations of the utmost importance. The remarkable role played by epigenetic modifications in repressing or activating many cancer-related genes and forming new epigenetic signatures can affect cancer initiation and progression. Hence, targeting the key epigenetic drivers could potentially attenuate cancer progression. MLLs, ARID1A and EZH2 are among the major epigenetic players that are frequently mutated in GACs. In this paper, we have proposed the existence of a network between these proteins that, together with PCAF and KDM6A, control the 3D chromatin structure and regulate the expression of tumor suppressor genes (TSGs) and oncogenes in GAC. Therefore, we suggest that manipulating the expression of EZH2, PCAF, and KDM6A or their downstream targets may reduce the cancerous phenotype in GAC.

Mixed Histology Is a Risk Factor for Lymph Node Metastasis in Early Gastric Cancer

BACKGROUND

The risk factors of lymph node (LN) metastasis are important factors to consider in endoscopic submucosal dissection in early gastric cancer (EGC). The aim of the study was to identify the correlation between mixed histology and LN metastasis in EGC.

METHODS

A total of 1645 patients who underwent curative radical gastrectomy for EGC were divided into three groups (pure differentiated [pure D], mixed, and pure undifferentiated [pure UD]) according to histologic type. They were subsequently analyzed retrospectively for LN metastasis. The patients who had mixed histology between differentiated and undifferentiated tubular adenocarcinoma were defined as mixed group.

RESULTS

The pure UD group was significantly younger than the other groups. Tumor size was larger in the mixed group. LN metastasis occurred more frequently in the mixed group and the pure UD group than in the pure D group (pure D, mixed, and pure UD, 7.7%, 23.2%, and 10.8%, respectively; P < 0.001). A logistic regression analysis revealed that the independent risk factors for LN metastasis were large tumor size (odd ratio [OR], 1.308), submucosal invasion (OR, 3.565), lymphovascular invasion (OR, 9.755), and histologic types of mixed (OR, 2.360) and pure UD (OR, 1.657).

CONCLUSIONS

Mixed histology is an important risk factor for LN metastasis in EGC. Thus, radical gastrectomy should be considered in the cases of mixed-type histology after endoscopic resection.

Thermoresponsive aerification and tissue vacuolization for facilitating endoscopic submucosal resection

BACKGROUND AND AIMS

Mucosal lifting and its persistence are critical for maintaining the operational space and preventing perforation in endoscopic operation. Although numerous agents have been investigated, optimization is still required for improving their clinical performance. In the present study, we proposed a novel concept of thermoresponsive aerification and tissue vacuolization for submucosal injection.

METHODS

Lifting performance and operational condition were first evaluated in porcine stomachs in vitro and rabbits in vivo. Dodecafluoropentane (DDFP) injection dosage, lifting persistency and operational assistance were quantitatively recorded. Gross and histological pathology were also analyzed to identify DDFP acute toxicity and long-term safety. The endoscopic submucosal dissection (ESD) procedure with DDFP was carried out on pigs in vivo to confirm its operational feasibility, efficacy, and safety.

RESULTS

Dodecafluoropentane aerification could achieve better mucosal lift with lower dosage (1% of normal saline dosage). Thermoresponsive DDFP aerification could provide continuous replenishment and longer persistence. Meanwhile, its tissue vacuolization effect significantly facilitated submucosal tissue dissection in in vitro study. Similar performance was verified in vivo. The particular vacuole-like submucosal structure was seen after DDFP onset, which also promoted reepithelization and wound healing. No tissue damage, gas embolism, biotoxicity, and physicochemical risk were observed.

CONCLUSION

Bioinert DDFP was feasible, efficient, and safe as the novel submucosal lifting candidate.

Long-Term Outcomes of Using Endoscopic Submucosal Dissection to Treat Early Gastric Cancer

Endoscopic submucosal dissection (ESD) is becoming the main procedure for the resection of early gastric cancer (EGC). The absolute indications for treating EGC with endoscopic resection were established by the Japanese Gastric Cancer Association and have been generally accepted. However, the absolute indications for treating EGC are rather strict, and expanded indications have been developed. Many studies have reported favorable long-term outcomes for patients who received curative resection for the expanded indication. ESD preserves the stomach, thereby improving patients’ quality of life compared to surgery; however, a generally higher incidence of metachronous gastric cancer has been reported after ESD for EGC. Therefore, clinicians must pay careful attention during surveillance endoscopy, even after a curative ESD.

Endoscopic submucosal dissection versus endoscopic mucosal resection for type 0-II superficial gastric lesions larger than 20 mm

Background:

Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) are increasingly used for the treatment of superficial gastrointestinal neoplasia. However, the limits and the indications for each technique are still debated. Our retrospective study aimed to compare these techniques in patients with gastric flat lesions larger than 20 mm without the non-lifting sign.

Methods:

Between January 2013 and July 2016, a total of 36 patients with early gastric flat lesions larger than 20 mm and without the non-lifting sign were resected by ESD and were followed up by endoscopy. As a control group, 40 EMR cases from our database were matched. En bloc and curative resection were compared between the two groups according to histological assessment, tumor size, recurrence, complication rate, and procedure time. A Kaplan-Meier comparison was performed for both groups with a log-rank test to compare the survival curves; the chi-square test was employed for other parameters.

Results:

En bloc resection rate and curative resection rate were significantly higher in the ESD group than in the EMR group. Procedure time was significantly longer in the ESD group. No significant differences were found in the recurrence and complication rates, although the former were higher in the EMR group and the latter in the ESD group. Survival curves were similar for both groups.

Conclusions:

Our retrospective analysis seems to confirm a clear advantage for ESD over EMR in removing early superficial gastric neoplasm. Although ESD has expanded the endoscopic resectability of endoscopic gastric lesions, EMR may still be considered one of the therapeutic options for flat gastric lesions without the non-lifting sign.

Measurement of tumor volume is not superior to diameter for prediction of lymph node metastasis in early gastric cancer with minute submucosal invasion

Background/Aim

The current indication for endoscopic resection in early gastric cancer (EGC) with minute (< 500 µm) submucosal invasion is based on tumor diameter, which may be insufficient to predict lymph node metastasis (LNM). We investigated whether tumor volume might more accurately predict LNM in EGC with minute submucosal invasion.

Materials and Methods

Among patients who underwent gastrectomy for gastric cancer, 346 with well/moderately differentiated EGC with submucosal invasion <500 µm were evaluated. Three-dimensional tumor volume was calculated using an endoscopically resected specimen and compared with 1-dimensional tumor diameter. Predictive ability of tumor diameter or volume for LNM was evaluated using receiver operating characteristic curve analysis.

Results

Tumor diameter and volume predicted LNM with an area under the curve (AUC) of 0.567 and 0.589, respectively. AUC, sensitivity, specificity, positive and negative predictive values, and accuracy of the 2 models were not significantly different. Tumor diameter ≥ 3 cm showed a significant association with LNM (odds ratio [OR], 2.57; 95% confidence interval [CI], 1.01–6.57; P = 0.049), whereas a tumor volume cutoff value of 752.8 cm3 showed no significant association with LNM (OR, 1.52; 95% CI, 0.59–3.88; P = 0.385).

Conclusions

Tumor volume had no advantage over diameter for predicting LNM in well/moderately differentiated EGC with minute submucosal invasion.