Serum Raman spectroscopy offers a promising minimally invasive approach for colorectal cancer (CRC) detection, but clinical translation has been limited by a fundamental sample-preparation problem: when a droplet dries on a conventional flat glass substrate, capillary flow and competitive protein adsorption drive suspended biomolecules toward the periphery, producing a ring-like enrichment pattern often described as a coffee-ring or Vroman-type effect and resulting in large spatial spectral variance. Here, we employed a hierarchical nanoporous layer (HNL) glass substrate whose superhydrophilic, three-dimensional porous architecture enables rapid and uniform biomolecular concentration, and integrated it with 1064 nm Raman spectroscopy and support vector machine (SVM) classification to develop a reproducible serum Raman platform for CRC detection and postoperative monitoring. Serum samples prospectively collected from 20 CRC patients preoperatively and postoperatively and from 20 age- and sex-matched healthy controls were analyzed. HNL glass reduced spatial spectral variance at 1450 cm-1 by approximately 4.6-fold compared with conventional glass while preserving spectral profiles, and the SVM achieved a mean test area under the ROC curve (AUC) of 0.9923 (standard deviation, 0.0102; range, 0.966-1.000) across 30 independent patient-level stratified train-validation-test splits. In a representative split, the patient-level ROC curve based on preoperative scores yielded an AUC of 1.000 for all 40 participants, although this point estimate should be interpreted cautiously given the small sample size. Principal component analysis (PCA) of patient-level mean spectra showed partial but visible separation between preoperative CRC and control groups, with PC1 and PC2 accounting for 23.2% and 12.8% of total variance, respectively. In an additional reproducibility experiment, three independently fabricated T-4800 HNL substrate batches showed an interbatch relative standard deviation (RSD) of 2.5% at 1450 cm-1 and pairwise spectral correlations of 0.9989-0.9992, whereas conventional soda-lime glass showed a spatial RSD of 10.9% under matched conditions. Longitudinally, CRC prediction scores decreased significantly after curative resection, whereas the score remained persistently elevated in a noncurative stage IV case. These proof-of-concept findings demonstrate that HNL-based serum Raman spectroscopy combined with SVM provides a reproducible sensing platform for CRC diagnosis and postoperative monitoring and warrant validation in larger multicenter cohorts.

BACKGROUND Cancer detection is a global research focus, and novel, rapid, and label-free techniques are being developed for routine clinical practice. This has led to the development of new tools and techniques from the bench side to routine clinical practice. In this study, we present a method that uses Raman spectroscopy (RS) to detect cancer in unstained formalin-fixed, resected specimens of the esophagus and stomach. Our method can record a clear Raman-scattered light spectrum in these specimens, confirming that the Raman-scattered light spectrum changes because of the histological differences in the mucosal tissue. AIM To evaluate the use of Raman-scattered light spectrum for detecting endoscop-ically resected specimens of esophageal squamous cell carcinoma (SCC) and gastric adenocarcinoma (AC). METHODS We created a Raman device that is suitable for observing living tissues, and attempted to acquire Raman-scattered light spectra in endoscopically resected specimens of six esophageal tissues and 12 gastric tissues. We evaluated formalin-fixed tissues using this technique and captured shifts at multiple locations based on feasibility, ranging from six to 19 locations 200 microns apart in the vertical and horizontal directions. Furthermore, a correlation between the obtained Raman scattered light spectra and histopathological diagnosis was performed. RESULTS We successfully obtained Raman scattered light spectra from all six esophageal and 12 gastric specimens. After data capture, the tissue specimens were sent for histopathological analysis for further processing because RS is a label-free methodology that does not cause tissue destruction or alterations. Based on data analysis of molecular-level substrates, we established cut-off values for the diagnosis of esophageal SCC and gastric AC. By analyzing specific Raman shifts, we developed an algorithm to identify the range of esophageal SCC and gastric AC with an accuracy close to that of histopathological diagnoses. CONCLUSION Our technique provides qualitative information for real-time morphological diagnosis. However, further in vivo evaluations require an excitation light source with low human toxicity and large amounts of data for validation.

Detecting cancers early on leads to better chances of successful treatment and long-term survival. There is no single test to diagnose cancers but available diagnostic procedures include diagnostic imaging, endoscopic exams and tumour biopsies. Prostate cancer is one of the most frequently diagnosed cancers and a prostate-specific antigen test (PSA) can be used in the detection of this type of cancer. This involves measuring the amount of PSA in the blood, with elevated levels possibly indicating prostate cancer. However, there are risks and limitations associated with existing diagnostic methods. Raman spectroscopy is an optical technique that shows promise in cancer diagnosis but there is room for improvement. At the Digestive Diseases Center, Showa University Koto Toyosu Hospital, Japan, researchers are using surface-enhanced Raman scattering (SERS) in the development of an ultra-early cancer diagnosis technology. Associate Professor Hiroaki Ito is collaborating with Associate Professor Uragami Naoyuki and Professors Noboru Yokoyama and Takashi Fukagai on this work and the researchers have established a high-sensitivity quantitative technology that uses near-infrared lasers as the excitation light source. The researchers have also developed a colorectal cancer prediction model based on Raman spectroscopy and, in another line of work, have developed a method for generating silver nanoscale hexagonal columns (NHCs) for use in SERS. Ultimately, Ito and the team hope their research will lead to enhanced cancer treatment results and improved quality of life for patients.

BACKGROUND Colorectal cancer (CRC) is an important disease worldwide, accounting for the second highest number of cancer-related deaths and the third highest number of new cancer cases. The blood test is a simple and minimally invasive diagnostic test. However, there is currently no blood test that can accurately diagnose CRC. AIM To develop a comprehensive, spontaneous, minimally invasive, label-free, blood-based CRC screening technique based on Raman spectroscopy. METHODS We used Raman spectra recorded using 184 serum samples obtained from patients undergoing colonoscopies. Patients with malignant tumor histories as well as those with cancers in organs other than the large intestine were excluded. Consequently, the specific diseases of 184 patients were CRC (12), rectal neuroendocrine tumor (2), colorectal adenoma (68), colorectal hyperplastic polyp (18), and others (84). We used the 1064-nm wavelength laser for excitation. The power of the laser was set to 200 mW. RESULTS Use of the recorded Raman spectra as training data allowed the construction of a boosted tree CRC prediction model based on machine learning. Therefore, the generalized R2 values for CRC, adenomas, hyperplastic polyps, and neuroendocrine tumors were 0.9982, 0.9630, 0.9962, and 0.9986, respectively. CONCLUSION For machine learning using Raman spectral data, a highly accurate CRC prediction model with a high R2 value was constructed. We are currently planning studies to demonstrate the accuracy of this model with a large amount of additional data.

Laparoscopic and endoscopic cooperative surgery (LECS) for gastric submucosal tumors (SMTs) has been developed under the concept of resecting gastric tumors with both complete curability and preserving organ functions.Precise resection is obtained by classical LECS, however, concerns regarding intraoperative bacterial infection and dissemination of the tumor cells into the abdominal cavity by LECS with exposure technique still remain.To prevent these concerns, several LECS-related procedures with nonexposure techniques, such as combination of laparoscopic and endoscopic approaches for neoplasia with nonexposure technique (CLEAN-NET) and non-exposed endoscopic wall-inversion surgery (NEWS), have been reported to be safe and feasible.Classical LECS, CLEAN-NET, and NEWS have the same concept, however, each has its own different characteristic procedures; exposure or non-exposure technique, inversion of the tumor into or outer the lumen, retrieval of tumor per oral or through the abdominal cavity, and dominance in the role of the endoscopist or the laparoscopic surgeon.Familiarization with these procedure details is important to understand their indications, advantages and limitations, resulting in providing a tailored minimally invasive surgery for patients.The main scope of this review article is to introduce readers to the clinical application, procedure, and results of CLEAN-NET, both from previous literatures and from our experience, as well as to offer a closer look at its advantages and limitations while comparing with other LECS procedures from the viewpoint of introducing CLEAN-NET first.

57 Background: Cancer is an important disease that accounts for many of the causes of death worldwide, and early diagnosis is important for improving treatment results. In medical care, blood test is a simple and excellent test method, but there is still no cancer blood diagnosis method with high accuracy that can be performed in general hospitals. We are trying to detect cancer patients by analyzing serum using Raman spectroscopy. Methods: Among the outpatients who underwent upper gastrointestinal endoscopy or colonoscopy, 236 subjects who agreed to participate in the study were included. Raman scattering spectra were measured by irradiating a 1064 nm wavelength laser for 15 seconds with serum collected from the subject before endoscopic examination. The average value measured a total of three times was taken as the measured value, and the three measured values were averaged to obtain the value of each examinee. In the obtained Raman scattering spectra, the scattering spectral intensities of the wavelength originating in the specific molecules were analyzed. Results: We were able to obtain clear Raman scattering spectra of all serum samples. When comparing the Raman scattering spectral intensities of the wavelength originating in specific molecules, a large number of serum measurement values were gathered at the center, and the measurement values of the cancer patients' serum were over low or high. By setting the appropriate cutoff line, cancer patients (gastric cancer or colon cancer) and non-cancerous persons could be relatively clearly distinguished (sensitivity, 100%; Specificity, 75%). Conclusions: Our micro Raman system is able to acquire Raman scattering spectra of serum samples. Furthermore, it has been suggested that cancer diagnosis using serum could be possible by comparing the scattering spectral intensities caused by specific molecules. Clinical trial information: UMIN000034306.

In this study, we utilized a stainless steel (SUS304) plate for measuring the Raman scattering spectra of body fluid samples. Using this stainless steel plate, we recorded the Raman scattering spectra of 99.5% ethanol and human serum samples by performing irradiation with 785- and 1064-nm lasers. Raman scattering spectra with intensities equal to or greater than those reported previously were obtained. In addition, the Raman scattering spectra acquired using the 1064-nm laser were less influenced by autofluorescence than those obtained via use of the shorter-wavelength laser. Moreover, the shapes of the spectra did not show any dependence on integration time, and denaturation of the samples was minimal. Our method, based on 1064-nm laser and the stainless steel plate, provides performance equal to or better than the methods reported thus far for the measurement of Raman scattering spectra from liquid samples. This method can be employed to rapidly evaluate the components of serum in liquid form without using surface-enhanced Raman scattering.

Integrated-type advanced endocytoscopy (AEC, GIF-Y0074 [prototype], Olympus Corp., Japan) was newly improved to provide high-definition (HD) images with ultrahigh magnification (×520 fold). AEC can visualize the cellular nuclei and cytoplasm of living cells during GI endoscopy with the double staining method using crystal violet and methylene blue. No data are available on the diagnostic usefulness of AEC for superficial squamous neoplasms. The aim of this study was to evaluate the diagnostic accuracy and concordance rate of AEC in the diagnosis of superficial esophageal squamous neoplasms. This was a retrospective study based on an image review at a single tertiary referral center. Three endoscopists with expertise in more than 50 procedures of EC participated in this study. An expert (Y.S.) collected AEC-HD images of 44 flat or superficial esophageal lesions, whose histology was established between June 2015 and October 2017. The other two experts (H.I. and K.G.), who were blinded to the histology, independently reviewed the images and diagnosed the lesions. Histology from biopsied or endoscopically removed specimen was used as the gold standard diagnostic tool. EC diagnosis was made based on the new simplified criteria that we modified a previously reported eriteria (Inoue H, et al. Gastrointest Endosc Clin N Am. 2004). ECA 1a was interpreted as normal; EC 1b, as an inflammation; EC 2, as an intraepithelial neoplasia (IN); and EC 3, as a squamous cell carcinoma (SCC) based on the density and size of the nucleus and shape of cells, and the frontline of cellular border. We calculated diagnostic accuracy values and concordance rate by using the κ value. The histologies of the 44 lesions were as follows: normal, 3; inflammation, 12; intraepithelial neoplasia, 4; and SCC, 25. The clinical characteristics of the 25 SCC lesions, which were inspected using AEC with double staining methods, were as follows: macroscopic type 0-IIa/b/c, 4/12/9; median diameter (interquartile range), 20 mm (14–30 mm); invasion depth of EP or LPM/MM/SM, 21/3/1. Images of 36 lesions (81.8%) were graded as high-quality EC images that were fully interpretable. The sensitivity, specificity, and overall accuracy of AEC for neoplastic lesions (EC 2 + 3 vs. EC 1a, b) were 83%, 74%, and 81%, respectively. In reviews with high level of confidence, sensitivity, specificity, and overall accuracy of AEC for neoplastic lesions were 90%, 100%, and 91%, respectively. The interobserver agreement between the two EC experts was 0.56 (p < 0.001). AEC with double staining method generally offered high-quality microscopic images. With a new simplified classification for superficial squamous neoplasms, AEC diagnosis with high reliability showed high accuracy values albeit a moderate reproducibility.

Lower esophageal sphincter (LES) dysfunction is known to be the main cause of gastroesophageal reflux disease (GERD). Although esophageal pH monitoring is considered the gold standard for the diagnosis of GERD, it is laborious and time consuming. Currently, there is no diagnostic method that can directly assess the function of LES endoscopically. We have recently developed a new diagnostic tool: endoscopic pressure study integrated system (EPSIS) that enables us to evaluate LES function endoscopically. The aim of this study was to evaluate the diagnostic performance of this novel diagnostic system. We conducted a retrospective study of patients who underwent both EPSIS and 24-hour impedance-pH monitoring at a single tertiary referral center from April 2016 to October 2017. EPSIS was performed at the time of gastroscopy by using a through-the-scope catheter connected to the system to measure intra-gastric pressure (IGP). Carbon dioxide was insufflated until LES loosens to evacuate the pressure by belching. The maximum IGP and waveform pattern of IGP (uphill or flat pattern) were recorded (Figure 1). On 24-hour impedance-pH monitoring, percentage of total time pH < 4 over 4.2%, DeMeester composite score over 14.7, and distal reflux event over 48 times on impedance monitoring were considered positive for GERD. We hypothesized as follows: (i) maximum IGP below 20mmHg and (ii) flat waveform pattern would correlate with GERD based upon a previously conducted preliminary study performed at our institution. The diagnostic performance of these findings was evaluated based on aforementioned positive findings on esophageal pH monitoring. A total of 54 patients with PPI-refractory acid reflux symptoms underwent both EPSIS and esophageal pH monitoring. The additional time of gastroscopy needed to perform EPSIS was less than 5 minutes in all cases. Both maximum IGP < 20mmHg and flat waveform pattern significantly correlated with percent total time pH < 4 over 4.2% (p < 0.01) and DeMeester composite score over 14.7 (p < 0.01). Twenty-five patients (44%) were diagnosed positive for GERD on pH monitoring. Forty patients (74.0%) were considered positive with maximum IGP < 20mmHg or flat waveform pattern recorded on EPSIS. Sensitivity, specificity, overall accuracy of positive EPSIS findings were 91.7% (95% CI, 0.73-0.99), 40.0% (95% CI, 0.23-0.59), 62.9% (95% CI, 0.49-0.76), respectively in the diagnosis of GERD by pH monitoring. EPSIS may be a promising detection tool that can be utilized to determine the pretest probability of esophageal pH monitoring in less than 5 minutes during gastroscopy. With this rapid and easily performed examination, EPSIS could be performed prior to proceeding with other diagnostic investigations for GERD.

It has been reported that the transient lower esophageal sphincter relaxation, low pressure of lower esophageal sphincter (LES) and abdominal strain are causes of gastroesophageal reflux disease (GERD). A hiatal hernia is often associated with GERD symptoms though some cases can be asymptomatic. LES can't be directly observed in forward viewing from the esophageal side on gastroscopy, however we hypothesized that LES can be activated and visualized by excessive insufflation in the retroflex view from the gastric side. We developed endoscopic pressure study integrated system (EPSIS) to evaluate comprehensively by combining "LES function by the retroflex viewing from the gastric side" and "continuous measurement of intra-gastric pressure (IGP)". The aim of this study was to evaluate the usefulness of EPSIS for GERD. This was a retrospective observational study in a single institution. Between November 2016 and November 2017, 72 patients with a hiatal hernia underwent EPSIS were included in this study. The EPSIS procedure is as follows: (1) routine observation; (2) observation of LES function in the retroflex view from the gastric side under excessive insufflation; and (3) continuous measurement of IGP by using through-the-scope catheter connected to the internal pressure measuring instrument. All procedures of EPSIS were performed with carbon dioxide insufflation under intravenous anesthesia. Patients were divided into two groups: Symptomatic group (GERD symptoms) (F-scale ≥8) (n=48) and asymptomatic group (F-scale <8) (n=24). We compared cardiac open (CO), sliding hernia (SH), the percentage of scope holding time (SHT %), maximum IGP (IGP max) and waveform pattern (uphill or flat pattern) of IGP between two groups. CO was defined as the length of cardiac opening excluding scope diameter and SH was defined as the distance from crura of diaphragm to squamo-columnar junction. These were reported using scope diameter (SD) which was about 1cm as a unit. SHT % (0 to 100%) was defined as the percentage of time that the esophageal mucosa held around the scope due to the contraction of the LES. CO and SH in symptomatic group was longer than those in asymptomatic group (2.2±1.1 SD vs 1.1±1.2 SD, p<0,001 and 1.3±1.1 SD vs 0.5±0.8 SD, p=0.004, respectively). SHT % and IGP max was significantly lower in asymptomatic group (42.9±28.7% vs 77.5±42.9%, p<0.001 and 18.1±5.1 mmHg vs 23.4±4.2 mmHg, p<0.001, respectively). The rate of flat waveform pattern of IGP in symptomatic group was higher than those in asymptomatic group (60.4% (29/48) vs 4.2% (1/24), p<0.001). SHT %, IGP max and waveform pattern of IGP had a strong correlation with GERD symptoms. EPSIS can measure the LES function endoscopically and may be useful for the diagnosis of GERD. EPSIS can be considered as a new diagnostic modality for GERD in the future.

AIM To investigate the possibility of diagnosing gastric cancer from an unstained pathological tissue using Raman spectroscopy, and to compare the findings to those obtained with conventional histopathology. METHODS We produced two consecutive tissue specimens from areas with and without cancer lesions in the surgically resected stomach of a patient with gastric cancer. One of the two tissue specimens was stained with hematoxylin and eosin and used as a reference for laser irradiation positioning by the spectroscopic method. The other specimen was left unstained and used for Raman spectroscopy analysis. RESULTS A significant Raman scattering spectrum could be obtained at all measurement points. Raman scattering spectrum intensities of 725 cm-1 and 782 cm-1, are associated with the nucleotides adenine and cytosine, respectively. The Raman scattering spectrum intensity ratios of 782 cm-1/620 cm-1, 782 cm-1/756 cm-1, 782 cm-1/1250 cm-1, and 782 cm-1/1263 cm-1 in the gastric adenocarcinoma tissue were significantly higher than those in the normal stomach tissue. CONCLUSION The results of this preliminary experiment suggest the feasibility of our spectroscopic method as a diagnostic tool for gastric cancer using unstained pathological specimens.

POEM (Per-oral endoscopic myotomy) has gained more and more popularity. In our hospital more than 1500 consecutive cases of achalasia and related disorders received POEM procedure in last 9 years. Short and middle term clinical results were satisfactory but potential risk of GERD after POEM was pointed out in some reports. Approximately 50% of POEM cases have reflux sign in 24hrs pH monitoring. In order to solve this potential disadvantage of POEM, endoscopic myotomy together with partial fundoplication (POEM+F) was developed and carried out as a pilot study (IRB approval number: 17T5010). Twelve consecutive cases with written informed consent received POEM+F. Right after completing myotomy, submucosal endoscope was advanced into peritoneal cavity. Pneumoperitoneum was achieved with CO2 insufflation through endoscope. Anterior wall of gastric fundus was grasped and anchored by 4 endoclips together with endoloop. Endoloop was fixed again to distal end of myotomy site by the other 3 endoclips (Figure 1). Endoloop was closed tightly under submucosal endoscopic visual control. Grasped anterior wall of gastric cardia was pulled up toward esophago-gastric junction. This traction created partial fundoplication at gastric cardia (Figure 2). POEM+F was successfully carried out in all cases. POEM+F created visually recognizable fundoplication at gastric cardia. Extended operating time was 36 minutes on average. Clinical course after POEM+F was uneventful. Hospital stay and dosage of pain controller was totally equal to conventional POEM procedure. 24hr pH impedance study of two months after POEM+F was carried out in 4 cases and no reflux was identified. POEM+F was technically feasible. In order to clarify anti-reflux effect of POEM+F needs to conduct RCT with large series. POEM+F is a pure NOTES procedure for esophageal achalasia.

Achalasia is considered to be a high-risk factor for the development of squamous cell carcinoma. Advances in endoscopic imaging facilitate the detection of superficial esophageal squamous cell carcinoma (SESCC). Little is known about the safety, efficacy, and postoperative course of endoscopic resection for SESCC in patients with achalasia. We have performed over 1500 per-oral endoscopic myotomy procedures for esophageal achalasia and its related diseases. We performed endoscopic resection for 14 patients with 25 SESCCs and conducted follow-up endoscopy after the treatment. The aim of this study was to evaluate the clinical outcomes of endoscopic resection for achalasia-associated SESCC. We conducted a retrospective cohort study of patients with achalasia-associated SESCC who underwent endoscopic resection at our university hospital from August 2010 to November 2017. SESCC was defined as high-grade intraepithelial neoplasia (HGIN) and squamous cell carcinoma in which invasion was confined to the submucosal layer. The patients were followed up with endoscopy at least once a year after endoscopic resection. The therapeutic outcome of endoscopic resection was determined by the last follow-up endoscopy and a telephone survey. Fourteen patients with achalasia underwent endoscopic resection for 25 SESCC lesions. There were 8 men and 6 women, and their median age was 62 years old (range, 43-83). The median disease duration was 20 years (range, 5-50). Sigmoid-type achalasia was seen in 9 cases (64%). Five patients (36%) had no prior history of smoking or drinking. We performed endoscopic resection (ESD/EMR, 23/2) in all cases. None of the patients experienced severe adverse events. The median tumor diameter was 26 mm (range, 7-70). The histological tumor depth of T1a-M (incl. HGIN)/T1b-SM was 24/1. Six patients (43%) had multiple neoplastic lesions. The en bloc resection rate was 100% (25/25), and the R0 resection rate was 96% (24/25). The median duration of follow-up surveillance was 19 months (range, 4-93). We found one case of recurrence in a patient who had undergone ESD. In this case, 2 recurrent tumors were mucosal carcinomas (T1a-EP and T1a-LPM) and were identified near the ESD scar 43 months after ESD. We performed successful ESD for the 2 recurrent tumors. No recurrence was found after ESD in any patient. None of the patients died during the study period. Endoscopic resection is suggested a safe and effective treatment for achalasia-associated SESCC with favorable outcomes.

Per-oral endoscopic myotomy (POEM) is becoming a standard treatment for achalasia and other esophageal motility disorders worldwide. POEM is considered less invasive treatment, as compared with conventional Heller’s myotomy. However, it is concerned that the lack of fundoplication after POEM may results in a high incidence of gastroesophageal reflux (GER). GER after POEM has been reported from various institutions and the risk factors of GER after POEM have not been well studied. The aim of this study was to clarify whether balloon dilation before POEM is associated with higher rate of postoperative GER or not. We retrospectively reviewed the medical records of 566 consecutive patients who underwent POEM for achalasia between March 2014 and July 2016 at Showa University Koto Toyosu Hospital. Using propensity score matching analysis, patients who underwent balloon dilation before POEM (n =137) were compared with patients who did not (n = 429). Propensity score matching was used to compensate for the differences in age, sex, Chicago classification, grade of esophageal dilation, orientation of myotomy, length of myotomy, and baseline Eckardt score. The rate of erosive esophagitis and GER symptoms after POEM were compared between both groups. The propensity score matching analysis yielded 123 matched pairs. Adjusted comparisons between the two groups showed a significantly higher rate of erosive esophagitis after POEM for the balloon dilation group than the other group (35.8% vs. 23.6%; P=0.039). GER symptom was also more common in balloon dilation group, but this was not statistically significant (21.1% vs. 12.1%; P=0.056). There was no significant difference in the postoperative Eckardt score between the two groups. Our results suggest that balloon dilation before POEM is associated with higher rate of postoperative GER. Although the balloon dilation is widely available and technically not difficult, it may be a risk factor of GER after POEM and should take this into consideration when performing balloon dilation before POEM.

We have performed over 1,200 per-oral endoscopy myotomy (POEM) cases for esophageal motility disorders since 2008. Treatment efficacy was assessed after pneumatic balloon dilatation (PBD) and laparoscopic Heller myotomy (LHM). Among high resolution manometry (HRM) subtypes, Type II achalasia showed best prognosis after PBD and LHM, while Type III achalasia showed worst prognosis. There have been no reports on treatment efficacy after POEM for each type of esophageal motility disorder. LHM was typically performed with a 4-6 cm esophageal myotomy and a 2-3 cm gastric myotomy. Although we initially performed >6 cm esophageal myotomy and >2-3 cm extended gastric myotomy in all cases, we have recently performed ≤6 cm esophageal myotomy and 2-3 cm gastric myotomy equivalent to that in standard LHM in cases of Type I/II achalasia, and extended myotomy for spastic esophageal disorders (SEDs), including Type III achalasia, jackhammer esophagus, and distal esophageal spasm.

Submucosal tumors (SMT) of the esophageal and gastric cardia require treatment when they increase in size or the patient experiences symptoms, such as dysphagia, even if the SMT is relatively small and benign. Surgical resection is needed for SMTs that originate from the muscularis propria. Surgical resection of SMTs in the esophageal and gastric cardia is more difficult and more invasive than for those in other portions of the stomach or gastrointestinal tract. In addition, surgery can cause esophageal strictures and deterioration of patients’ quality of life. We developed per-oral endoscopic tumor resection (POET) as a minimally invasive endoscopic treatment for SMTs of the esophageal and gastric cardia and reported this procedure (Inoue H, et al. Endoscopy, 2012). At the same time this procedure was reported independently as submucosal tunneling endoscopic resection (STER) (Xu MD, Zhou PH, et al. Gastrointest Endosc, 2012). POET and STER are similar procedure. However, knowledge about the feasibility and therapeutic outcomes of POET is limited.