The Usefulness of Magnifying Endoscopy and Narrow-Band Imaging in Measuring the Depth of Invasion before Endoscopic Submucosal Dissection

A comprehensive update on early gastric cancer: defining terms, etiology, and alarming risk factors

INTRODUCTION

Early gastric cancer (EGC) is a well-defined gastric malignancy that is limited to the mucosa or submucosa, irrespective of lymph node metastasis. At an early stage, gastric cancer often does not cause symptoms until it becomes advanced, and it is a heterogeneous disease and usually encountered in its late stages.

AREA COVERED

This comprehensive review will provide a novel insight into the evaluation of EGC epidemiology, defining terms, extensive etiology and risk factors, and timely diagnosis since prevention is an essential approach for controlling this cancer and reducing its morbidity and mortality.

EXPERT OPINION

The causative manner of EGC is complex and multifactorial. In recent years, researchers have made significant contributions to understanding the etiology and pathogenesis of EGC, and standardization in the evaluation of disease activity. Though the incidence of this cancer is steadily declining in some advanced societies owing to appropriate interventions, there remains a serious threat to health in developing nations. Early detection of resectable gastric cancer is crucial for better patient outcomes.

Exploring the possibility of endoscopic submucosal dissection for clinical submucosal invasive early gastric cancers

BACKGROUND

The current standard treatment modality for clinical submucosal invasive (cT1b) early gastric cancer (EGC) is surgery. However, there are discrepancies in T staging between pre- and post-operative findings, and in cases of overestimation, patients may lose the opportunity to preserve the stomach. The aim of this study was to analyze surgical outcomes of cT1b EGC and determine the pre-treatment factors favoring ESD.

METHODS

Patients who underwent gastrectomy for cT1b EGC with a tumor size of 30 mm or less in diameter and differentiated-type histology were retrospectively reviewed from January 2010 to December 2014. According to the final surgical pathologic results, two groups were classified: patients whose pathologic results qualified for current ESD indication (ESD-qualified group, n = 203) and patients whose pathologic results made them ineligible for ESD (ESD-disqualified group, n = 261). The preoperative clinical characteristics were compared.

RESULTS

Forty-three percent of the patients (203/464) who underwent gastrectomy for cT1b EGC qualified for ESD; their endoscopic lesion tended to be smaller than 20 mm in size and located in the distal part of stomach. In addition, the ESD-qualified group showed a significantly higher proportion of well-differentiated tubular adenocarcinoma on endoscopic biopsy and of the flat/depressed type in the endoscopic evaluation.

CONCLUSION

Forty-three percent of the patients with cT1b EGC who underwent gastrectomy had a chance to preserve their stomach by ESD. Therefore, pre-treatment factors such as endoscopic lesion size, location, histology, and gross type should be considered for treatment modality selection for cT1b EGC.

Comparison of endoscopic ultrasonography and magnifying endoscopy for assessment of the invasion depth of shallow gastrointestinal neoplasms: a systematic review and meta-analysis

OBJECTIVES

To conduct a meta-analysis to provide accurate evidence regarding the preferred diagnostic method, magnifying endoscopy (ME) or endoscopic ultrasonography (EUS), for assessment of the depth of invasion of the gastrointestinal neoplasms.

METHODS

PubMed, EMBASE, Ovid Medline, and the Cochrane Library databases were searched for studies published between January 1946 and October 2016, regarding the use of EUS and ME to assess the invasion depth of gastrointestinal cancers. The quality of diagnostic studies was evaluated using the QUADAS2 instrument. The Meta-DiSc software (version 1.4) was used for meta-analysis of the pooled data regarding the diagnostic accuracy of EUS and ME of the invasion depth of gastrointestinal neoplasms.

RESULTS

Our meta-analysis included the data of 754 patients with gastrointestinal cancers contributed by seven prospective studies. All studies were of high quality (QUADAS2). The receiver operating characteristic (ROC) planes were not observed in shoulder and arm forms for either EUS or ME, with Spearman's correlation coefficients of -0.821 and 0.234 for EUS and ME, respectively. The p values of the diagnostic odds ratio for EUS and ME were 0.0038 and 0.0131, respectively. The sensitivity and specificity of EUS for the diagnosis of the depth of invasion of gastrointestinal cancers were 0.75 (95% CI 0.69-0.81) and 0.84 (95% CI 0.79-0.88), respectively. In comparison, the sensitivity and specificity for ME were 0.74 (95% CI 0.67-0.69) and 0.85 (95% CI 0.80-0.89), respectively. The values of area under the summary ROC (SROC) curves for EUS and ME were 0.8499 and 0.8757, respectively, with a non-significant Z value between EUS and MR (0.296 < 1.96).

CONCLUSIONS

Both EUS and ME provide a comparable performance for judging the depth of invasion of gastrointestinal neoplasms. However, there is heterogeneity between studies contributed by non-threshold effects.

Efficacy Evaluation of SAVE for the Diagnosis of Superficial Neoplastic Lesion

The detection of non-polypoid superficial neoplastic lesions using current standard of white light endoscopy surveillance and random biopsy is associated with high miss rate. The subtle changes in mucosa caused by the flat and depressed neoplasms often go undetected and do not qualify for further investigation, e.g., biopsy and resection, thus increasing the risk of cancer advancement. This paper presents a screening tool named the saliency-aided visual enhancement (SAVE) method, with an objective of highlighting abnormalities in endoscopic images to detect early lesions. SAVE is a hybrid system combining image enhancement and saliency detection. The method provides both qualitative enhancement and quantitative suspicion index for endoscopic image regions. A study to evaluate the efficacy of SAVE to localize superficial neoplastic lesion was performed. Experimental results for average overlap index >0.7 indicated that SAVE was successful to localize the lesion areas. The area under the receiver-operating characteristic curve obtained for SAVE was 94.91%. A very high sensitivity (100%) was achieved with a moderate specificity (65.45%). Visual inspection showed a comparable performance of SAVE with chromoendoscopy to highlight mucosal irregularities. This paper suggests that SAVE could be a potential screening tool that can substitute the application of burdensome chromoendoscopy technique. SAVE method, as a simple, easy-to-use, highly sensitive, and consistent red flag technology, will be useful for early detection of neoplasm in clinical applications.

Early Gastric Cancer: Current Advances of Endoscopic Diagnosis and Treatment

Endoscopy is a major method for early gastric cancer screening because of its high detection rate, but its diagnostic accuracy depends heavily on the availability of endoscopic instruments. Many novel endoscopic techniques have been shown to increase the diagnostic yield of early gastric cancer. With the improved detection rate of EGC, the endoscopic treatment has become widespread due to advances in the instruments available and endoscopist's experience. The aim of this review is to summarize frequently-used endoscopic diagnosis and treatment in early gastric cancer (EGC).

Relationships between Micro-Vascular and Iodine-Staining Patterns in the Vicinity of the Tumor Front of Superficial Esophageal Squamous Carcinoma

Objective

The aim of the present study was to clarify differences between micro-vascular and iodine-staining patterns in the vicinity of the tumor fronts of superficial esophageal squamous cell carcinomas (ESCCs).

Methods

Ten consecutive patients with ESCCs who were treated by endoscopic submucosal dissection (ESD) were enrolled. At the edge of the iodine-unstained area, we observed 183 sites in total using image-enhanced magnifying endoscopy. We classified the micro-vascular and iodine-staining patterns into three types: Type A, in which the line of vascular change matched the border of the iodine-unstained area; Type B, in which the border of the iodine-unstained area extended beyond the line of vascular change; Type C, in which the line of vascular change extended beyond the border of the iodine-unstained area. Then, by examining histopathological sections, we compared the diameter of intra-papillary capillary loops (IPCLs) in cancerous areas and normal squamous epithelium.

Results

We investigated 160 sites that the adequate quality of pictures were obtained. There was no case in which the line of vascular change completely matched the whole circumference of the border of an iodine-unstained area. Among the 160 sites, type A was recognized at 76 sites (47.5%), type B at 79 sites (49.4%), and type C at 5 sites (3.1%). Histological examination showed that the mean diameter of the IPCLs in normal squamous epithelium was 16.2±3.7μm, whereas that of IPCLs in cancerous lesions was 21.0±4.4μm.

Conclusions

The development of iodine-unstained areas tends to precede any changes in the vascularity of the esophageal surface epithelium.

Transoral surgery for laryngo-pharyngeal cancer - The paradigm shift of the head and cancer treatment

Transoral surgery is a less invasive treatment that is becoming a major strategy in the treatment of laryngo-pharyngeal cancer. It is a minimally invasive approach that has no skin incision and limits the extent of tissue dissection, disruption of speech and swallowing muscles, blood loss, damage to major neurovascular structures, and injury to normal tissue. Transoral approaches to the laryngo-pharynx, except for early glottis cancer, had been limited traditionally to tumors that can be observed directly and manipulated with standard instrumentation and lighting. Since the 1990s, transoral laser microsurgery (TLM) has been used as an organ preservation strategy with good oncological control and good functional results, although it has not been widely used because of its technical difficulty. Recently, transoral robotic surgery (TORS) is becoming popular as a new treatment modality for laryngo-pharyngeal cancer, and surgical robots are used widely in the world since United States FDA approval in 2009. In spite of the global spread of TORS, it has not been approved by the Japan FDA, which has led to the development of other low-cost transoral surgical techniques in Japan. Transoral videolaryngoscopic surgery (TOVS) was developed as a new transoral surgery system for laryngo-pharyngeal lesions to address the problems of TLM. In TOVS, a rigid endoscope is used to visualize the surgical field instead of a microscope and the advantages of TOVS include the wide operative field and working space achieved using the distending laryngoscope and videolaryngoscope. Also, with the spread of narrow band imaging (NBI), endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD), which are widely used for superficial cancers in the gastrointestinal tract, have been applied for the superficial laryngo-pharyngeal cancer. Both EMR and ESD are performed mainly by gastroenterologists with a sharp dissector and magnifying endoscopy (ME)-NBI with minimal surgical margin. Endoscopic laryngo-pharyngeal surgery (ELPS) was developed to treat laryngo-pharyngeal superficial cancer by modifying the ESD procedure. The concept of ELPS is the same as that of ESD, however, the resection procedure is performed by a head and neck surgeon with both hands using a ME-NBI and rigid curved laryngo-pharyngoscope. These four procedures are low cost with similar oncological and functional outcomes to TORS. TORS may be less expensive than chemoradiotherapy, but the number of hospitals that can afford da Vinci surgical systems is limited. Even in the era of robotic surgery, these four procedures will be good options for laryngo-pharyngeal cancer.

Diagnostic performance of magnifying narrow-band imaging for early gastric cancer: A meta-analysis

AIM: To investigate the performance of magnifying endoscopy with narrow-band imaging (ME-NBI) in the diagnosis of early gastric cancer (EGC).

METHODS: Systematic literature searches were conducted until February 2014 in PubMed, EMBASE, Web of Science, Ovid, Scopus and the Cochrane Library databases by two independent reviewers. Meta-analysis was performed to calculate the pooled sensitivity, specificity and diagnostic odds ratio and to construct a summary receiver operating characteristic (ROC) curve. Subgroup analyses were performed based on the morphology type of lesions, diagnostic standard, the size of lesions, type of assessment, country and sample size to explore possible sources of heterogeneity. A Deeks’ asymmetry test was used to evaluate the publication bias.

RESULTS: Fourteen studies enrolling 2171 patients were included. The pooled sensitivity, specificity and diagnostic odds ratio for ME-NBI diagnosis of EGC were 0.86 (95%CI: 0.83-0.89), 0.96 (95%CI: 0.95-0.97) and 102.75 (95%CI: 48.14-219.32), respectively, with the area under ROC curve being 0.9623. Among the 14 studies, six also evaluated the diagnostic value of conventional white-light imaging, with a sensitivity of 0.57 (95%CI: 0.50-0.64) and a specificity of 0.79 (95%CI: 0.76-0.81). When using “VS” (vessel plus surface) ME-NBI diagnostic systems in gastric lesions of depressed macroscopic type, the pooled sensitivity and specificity were 0.64 (95%CI: 0.52-0.75) and 0.96 (95%CI: 0.95-0.98). For the lesions with a diameter less than 10 mm, the sensitivity and specificity were 0.74 (95%CI: 0.65-0.82) and 0.98 (95%CI: 0.97-0.98).

CONCLUSION: ME-NBI is a promising endoscopic tool in the diagnosis of early gastric cancer and might be helpful in further target biopsy.

New approaches to gastric cancer staging: Beyond endoscopic ultrasound, computed tomography and positron emission tomography

Currently, there is no single gold standard modality for staging of gastric cancer and several methods have been used complementarily in the each clinical situation. To make up for the shortcomings of conventional modalities such as endoscopic ultrasound, computed tomography and ¹⁸F-fluoro-2-deoxyglucose positron emission tomography, numerous attempts with new approaches have been made for gastric cancer staging. For T staging, magnifying endoscopy with narrow-band was evaluated to differentiate mucosal cancer from submucosal cancer. Single/double contrast-enhanced ultrasound and diffusion-weighted magnetic resonance imaging were also tried to improve diagnostic accuracy of gastric cancer. For intraoperative staging with sentinel node mapping, indocyanine green infrared and fluorescence imaging was introduced. In addition, to detect micrometastasis, real-time reverse transcription-polymerase chain reaction system with multiple markers was studied. Staging laparoscopy using 5-aminolevulinic acid-mediated photodynamic diagnosis and percutaneous diagnostic peritoneal lavage were also evaluated. However, most studies reporting new staging methods is preliminary and further studies for validation in clinical practice are needed. In this mini-review, we discuss new progress in gastric cancer staging. Especially, we focus on new diagnostic approach to gastric cancer staging beyond the conventional modalities and briefly review the remarkable clinical results of the studies published over the past three years.

Is image-enhanced endoscopy useful for the diagnosis and treatment of gastrointestinal tumor?

Since the introduction of endoscopic submucosal dissection method for the treatment of early gastric cancer, endoscopic treatment of early gastric cancer has increased exponentially. Accordingly, early diagnosis of cancerous or precancerous lesion has become one of the most important missions for endoscopists. The desire to improve diagnostic capability of white light endoscopy led to the development of new imaging techniques called "image enhanced endoscopy." The usefulness of these image enhanced endoscopy has not been proven yet, although there are several studies reporting diagnostic superiority of these new imaging methods over white light endoscopy. Among these new imaging modalities, narrow band image (NBI) with magnification endoscopy has been most widely used and studied. This manuscript will be focused on the NBI with magnification endoscopy.