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Submucosal invasive (T1) colorectal cancer is a significant clinical management challenge, with an estimated 10% of patients developing extraintestinal lymph node metastasis. This condition necessitates surgical resection along with lymph node dissection to achieve a curative outcome. Thus, the precise preoperative assessment of lymph node metastasis risk is crucial to guide treatment decisions after endoscopic resection. Contemporary clinical guidelines strive to identify a low-risk cohort for whom endoscopic resection will suffice, applying stringent criteria to maximize patient safety. Those failing to meet these criteria are often recommended for surgical resection, with its associated mortality risks although it may still include patients with a low risk of metastasis. In the quest to enhance the precision of preoperative lymph node metastasis risk prediction, innovative models leveraging artificial intelligence or nomograms are being developed. Nevertheless, the debate over the ideal sensitivity and specificity for such models persists, with no consensus on target metrics. This review puts forth postoperative mortality rates as a practical benchmark for the sensitivity of predictive models. We underscore the importance of this method and advocate for research to amass data on surgical mortality in T1 colorectal cancer. Establishing specific benchmarks for predictive accuracy in lymph node metastasis risk assessment will hopefully optimize the treatment of T1 colorectal cancer.

Background: Neoadjuvant therapy (NAT) before radical surgery are effective treatments for locally advanced rectal cancer. However, the treatment strategy after NAT and surgery is still unclear. It is difficult to accurately evaluate the stage before NAT, as some cases are downstaged by NAT. Objective: We investigated the treatment strategies based on the postoperative pathology of patients with yStage Ⅰ or Ⅱ rectal cancer who underwent NAT and radical resection. Design: They patients were retrospectively evaluated the long-term outcomes. They were divided into patients with yStage I/II receiving NAT and patients with stage I/II patients without NAT (non-NAT). Disease-free survival (DFS) and overall survival (OS) were examined, and the prognosis was compared. Cox proportional hazard model was used to examine the recurrence risk factors in all patients or NAT. We compared the effects of adjuvant therapy in NAT. Patients: Overall, 521 patients histologically diagnosed with yStage I/II or stage I/II who underwent surgery for rectal cancer between April 2001 and July 2019 were eligible. Results: The NAT and non-NAT groups included 80 and 441 patients, respectively. DFS was significantly lower in NAT, but there was no difference in OS between the two groups. All patients had several recurrence risk factors, but none of the NAT had such risk factors. No significant difference in DFS and OS was found between NAT with and without adjuvant chemotherapy. Limitation: This is a single-center retrospective study. Conclusions: NAT had lower DFS than non-NAT, but no difference in OS was observed. No significant recurrence risk factors were observed in NAT. Adjuvant chemotherapy for NAT may have no benefit.

The current standard treatment for muscularis propria-invasive (T2) colorectal cancer is surgical colectomy with lymph node dissection. With the advent of new endoscopic resection techniques, such as endoscopic full-thickness resection or endoscopic intermuscular dissection, T2 colorectal cancer, with metastasis to 20%-25% of the dissected lymph nodes, may be the next candidate for endoscopic resection following submucosal-invasive (T1) colorectal cancer. We present a novel endoscopic treatment strategy for T2 colorectal cancer and suggest further study to establish evidence on oncologic and endoscopic technical safety for its clinical implementation.

Abstract Objectives Endoscopic submucosal dissection (ESD) is an effective procedure for the en bloc resection of colorectal neoplasms. However, risk factors for local recurrence after ESD have not been identified. This study aimed to evaluate such risk factors after ESD for colorectal neoplasms. Methods This retrospective study included 1344 patients with 1539 consecutive colorectal lesions who underwent ESD between September 2003 and December 2019. We investigated various factors associated with local recurrence in these patients. The main outcomes were the incidence of local recurrence and its relationship with clinicopathological factors during long‐term surveillance. Results The en bloc resection rate was 98.6%, the R0 resection rate was 97.2%, and the histologically complete resection rate was 92.7%. Local recurrence was observed in 7/1344 (0.5%) patients and the median follow‐up period was 72 months (range 4–195 months). The incidence of local recurrence was significantly higher in lesions ≥40 mm in diameter (hazard ratio [HR] 15.68 [1.88–130.5]; p = 0.011), piecemeal resection (HR 48.42 [10.7–218.7]; p < 0.001), non‐R0 resection (HR 41.05 [9.025–186.7]; p < 0.001), histologically incomplete resection (HR 16.23 [3.627–72.63]; p

Abstract Objectives A “resect‐and‐discard” strategy has been proposed for diminutive adenomas in the colorectum. However, this strategy is sometimes difficult to implement because of the lack of confidence in differentiating low‐grade adenoma (LGA) from advanced lesions such as high‐grade adenoma or carcinoma. To perform real‐time precise diagnosis of LGA with high confidence, we assessed whether endocytoscopy (EC) diagnosis, considering normal pit‐like structure (NP‐sign), an excellent indicator of LGA, could have additional diagnostic potential compared with conventional modalities. Methods All the neoplastic lesions that were observed by non‐magnifying narrow‐band imaging (NBI), magnifying NBI (M‐NBI), magnifying pit pattern, and EC prior to pathological examination between 2005 and 2018 were retrospectively investigated. The neoplastic lesions were classified into two categories: LGA and other neoplastic lesions. We assessed the differential diagnostic ability of EC with NP‐sign between LGA and other neoplastic lesions compared with that of NBI, M‐NBI, pit pattern, and conventional EC in terms of sensitivity, specificity, accuracy, and area under the receiver operating characteristic curve (AUC). Results A total of 1376 lesions from 1097 patients were eligible. The specificity (94.9%), accuracy (91.5%), and area under the receiver operating characteristic curve (0.95) of EC with NP‐sign were significantly higher than those of NBI, M‐NBI, pit pattern, and conventional EC. Conclusions EC diagnosis with NP‐sign has significantly higher diagnostic performance for predicting colorectal LGA compared with the conventional modalities and enables stratification of neoplastic lesions for “resect‐and‐discard” with higher confidence.

Abstract Objectives Japanese guidelines include high‐grade (poorly differentiated) tumors as a risk factor for lymph node metastasis (LNM) in T1 colorectal cancer (CRC). However, whether the grading is based on the least or most predominant component when the lesion consists of two or more levels of differentiation varies among institutions. This study aimed to investigate which method is optimal for assessing the risk of LNM in T1 CRC. Methods We retrospectively evaluated 971 consecutive patients with T1 CRC who underwent initial or additional surgical resection from 2001 to 2021 at our institution. Tumor grading was divided into low‐grade (well‐ to moderately differentiated) and high‐grade based on the least or predominant differentiation analyses. We investigated the correlations between LNM and these two grading analyses. Results LNM was present in 9.8% of patients. High‐grade tumors, as determined by least differentiation analysis, accounted for 17.0%, compared to 0.8% identified by predominant differentiation analysis. A significant association with LNM was noted for the least differentiation method (p < 0.05), while no such association was found for predominant differentiation (p = 0.18). In multivariate logistic regression, grading based on least differentiation was an independent predictor of LNM (p = 0.04, odds ratio 1.68, 95% confidence interval 1.00–2.83). Sensitivity and specificity for detecting LNM were 27.4% and 84.1% for least differentiation, and 2.1% and 99.3% for predominant differentiation, respectively. Conclusions Tumor grading via least differentiation analysis proved to be a more reliable measure for assessing LNM risk in T1 CRC compared to grading by predominant differentiation.

PURPOSELimited information is available regarding the characteristics and outcomes of stage IV small bowel adenocarcinoma (SBA) in Japan. This study examined the clinical and pathological characteristics and outcomes according to the treatment strategies in patients with stage IV SBA.METHODSThis retrospective observational study used the data of patients with jejunal or ileal adenocarcinoma collected by the Small Bowel Malignant Tumor Project of the Japanese Society for Cancer of the Colon and Rectum. Descriptive statistics were expressed as the mean (standard deviation) or median (range). Survival analysis was performed using Kaplan-Meier curves and pairwise log-rank tests.RESULTSData from 128 patients were analyzed. The treatment strategies were chemotherapy alone (26 of 128, 20.3%), surgery alone (including palliative surgery; 21 of 128, 16.4%), surgery + chemotherapy (74 of 128, 57.8%), and best supportive care (7 of 128, 5.5%). The median (range) overall survival was 16 (0-125) months overall, and 11 (1-38) months, 8 (0-80) months, 18 (0-125) months, and 0 (0-1) months for the chemotherapy, surgery, surgery + chemotherapy, and best supportive care groups, respectively. Three main categories of chemotherapeutic regimen were used: a combination of fluoropyrimidine and oxaliplatin (F + Ox), fluoropyrimidine and irinotecan (F + Iri), and single-agent fluoropyrimidine. Among patients treated with chemotherapy, the median (range) OS was 16 (1-106) months overall, and 17 (1-87) months, 29 (7-39) months, and 16 (1-106) months in patients treated with fluoropyrimidine, F + Iri, and F + Ox, respectively.CONCLUSIONPatients treated with surgery, chemotherapy, or both had a better prognosis than those who received best supportive care. Among patients who received chemotherapy, survival did not differ according to the chemotherapeutic regimen.

The incidence of T1 colorectal cancer is expected to increase because of the prevalence of colorectal cancer screening and the progress of endoscopic treatment such as endoscopic submucosal dissection or endoscopic full-thickness resection. Currently, the requirement for additional surgery after endoscopic resection of T1 colorectal cancer is determined according to several treatment guidelines (in USA, Europe, and Japan) referring to the following pathological findings: lymphovascular invasion, tumor differentiation, depth of invasion, and tumor budding, all of which are reported to be risk factors for lymph node metastasis. In addition to these factors, in this review, we investigate whether tumor location, which is an objective factor, has an impact on the presence of lymph node metastasis and recurrence. From recent studies, left-sided location, especially the sigmoid colon in addition to rectum, could be a risk factor for lymph node metastasis and cancer recurrence. The treatment of T1 colorectal cancer should be managed considering these findings.

With the widely spreading population-based screening programs for colorectal cancer and recent improvements in endoscopic diagnosis, the number of endoscopic resections in subjects with T1 colorectal cancer has been increasing. Some reports suggest that endoscopic resection prior to surgical resection of T1 colorectal cancer has no adverse effect on prognosis and contributes to this tendency. The decision on the need for surgical resection as an additional treatment after endoscopic resection of T1 colorectal cancer should be made according to the metastasis risk to lymph nodes based on histopathological findings. Because lymph node metastasis occurs in approximately 10% of patients with T1 colorectal cancer according to current international guidelines, the remaining 90% of patients may be at an increased risk of surgical resection and associated postoperative mortality, with no clinical benefit derived from unnecessary surgical resection. Although a more accurate prediction system for lymph node metastasis is needed to solve this problem, risk stratification for lymph node metastasis remains controversial. In this review, we focus on the current status of risk stratification of T1 colorectal cancer metastasis to lymph nodes and outline future perspectives.

Endocytoscopy (EC) is a contact-type optical endoscope that allows in vivo cellular observation during gastrointestinal endoscopy and is now commercially available not only in Japan but also in Asian, European Union, and Middle Eastern countries. EC helps conduct a highly accurate pathological prediction without biopsy. Initially, EC was reported to be effective for esophageal diseases. Subsequently, its efficacy for stomach and colorectal diseases has been reported. In this narrative review, we searched for clinical studies that investigated the efficacy of EC. EC seems to accurately diagnose gastrointestinal diseases without biopsy. Most of the studies aimed to clarify the relationship between endocytoscopic findings of gastrointestinal neoplasia and pathological diagnosis. Some studies have investigated non-epithelial lesions or diseases, such as inflammatory bowel disease or infectious diseases. However, there are few high-level pieces of evidence, such as randomized trials; thus, further studies are needed.

Abstract Obesity is a positive predictor of surgical morbidity. There are few reports of laparoscopic cholecystectomy (LC) outcomes in obese patients. This study aimed to clarify this relationship. This retrospective study included patients who underwent LC at Showa University Northern Yokohama Hospital between January 2017 and April 2020. A total of 563 cases were examined and divided into two groups: obese (n = 142) (BMI ≥ 25 kg/m2) and non-obese (n = 241) (BMI

Integrating artificial intelligence (AI) applications into colonoscopy practice is being accelerated as deep learning technologies emerge. In this field, most of the preceding research has focused on polyp detection and characterization, which can mitigate inherent human errors accompanying colonoscopy procedures. On the other hand, more challenging research areas are currently capturing attention: the automated prediction of invasive cancers. Colorectal cancers (CRCs) harbor potential lymph node metastasis when they invade deeply into submucosal layers, which should be resected surgically rather than endoscopically. However, pretreatment discrimination of deeply invasive submucosal CRCs is considered difficult, according to previous prospective studies (e.g.,

Background and Aim Although colorectal laterally spreading tumors (LSTs) can be classified into four subtypes, the histopathological characteristics are known to differ among these subtypes. We therefore performed a logistic regression analysis to determine whether the risk of pathological T1 cancer of large colorectal LSTs can be predicted based on factors such as endoscopic findings in a large group of patients enrolled in a multicenter study in Japan. Methods In the main study, we assessed 1236 colorectal adenomas or early cancers that were classified as LSTs measuring 20 mm or more in diameter and treated endoscopically. Logistic regression analysis was performed to determine whether factors such as the subtype of LST could be used to predict the risk of pathological T1 cancer. A validation study of 356 large colorectal LSTs was conducted to confirm the validity of the results obtained in the main study. Results The locations and tumor diameter of the LSTs in the main study were found to differ significantly according to the LST subclassification (P

Background Colorectal cancer (CRC) can be classified into four consensus molecular subtypes (CMS) according to genomic aberrations and gene expression profiles. CMS is expected to be useful in predicting prognosis and selecting chemotherapy regimens. However, there are still no reports on the relationship between the morphology and CMS. Methods This retrospective study included 55 subjects with T2 CRC undergoing surgical resection, of whom 30 had the depressed type and 25 the protruded type. In the classification of the CMS, we first defined cases with deficient mismatch repair as CMS1. And then, CMS2/3 and CMS4 were classified using an online classifier developed by Trinh et al. The staining intensity of CDX2, HTR2B, FRMD6, ZEB1, and KER and the percentage contents of CDX2, FRMD6, and KER are input into the classifier to obtain automatic output classifying the specimen as CMS2/3 or CMS4. Results According to the results yielded by the online classifier, of the 30 depressed-type cases, 15 (50%) were classified as CMS2/3 and 15 (50%) as CMS4. Of the 25 protruded-type cases, 3 (12%) were classified as CMS1 and 22 (88%) as CMS2/3. All of the T2 CRCs classified as CMS4 were depressed CRCs. More malignant pathological findings such as lymphatic invasion were associated with the depressed rather than protruded T2 CRC cases. Conclusions Depressed-type T2 CRC had a significant association with CMS4, showing more malignant pathological findings such as lymphatic invasion than the protruded-type, which could explain the reported association between CMS4 CRC and poor prognosis.

Background and study aims We sometimes encounter colorectal cancer (CRC) that is discovered during the time interval between initial colonoscopy and the recommended follow-up examination. Although several studies reported such cases of CRC, most were based on registry data, which implied that the endoscopic quality was not consistent or guaranteed. We aimed to clarify these clinical and endoscopic characteristics at our high-volume center where a retrospective survey could be precisely performed. Patients and methods We retrospectively analyzed patients with CRC who underwent endoscopic resection or surgery from April 2002 to December 2010, categorizing them into two groups: a “study group” of patients with a negative colonoscopy during the previous 10 years, and a “control group” of patients without a previous colonoscopy or with a previous colonoscopy more than 10 years prior. Results A total of 2042 patients had CRC, among which 55 patients were classified into the study group and the remaining 1989 into the control group. The CRC cases in the study group showed a significant association with smaller (

Background and study aims Large adenomas are sometimes misidentified as cancers during colonoscopy and are surgically removed. To address this overtreatment, we developed an artificial intelligence (AI) tool that identified cancerous pathology in vivo with high specificity. We evaluated our AI tool under the supervision of a government agency to obtain regulatory approval. Patients and methods The AI tool outputted three pathological class predictions (cancer, adenoma, or non-neoplastic) for endocytoscopic images obtained at 520-fold magnification and previously trained on 68,082 images from six academic centers. A validation test was developed, employing 500 endocytoscopic images taken from various parts of randomly selected 50 large (≥ 20 mm) colorectal lesions (10 images per lesion). An expert board labelled each of the 500 images with a histopathological diagnosis, which was made using endoscopic and histopathological images. The validation test was performed using the AI tool under a controlled environment. The primary outcome measure was the specificity in identifying cancer. Results The validation test consisted of 30 cancers, 15 adenomas, and five non-neoplastic lesions. The AI tool could analyze 83.6 % of the images (418/500): 231 cancers, 152 adenomas, and 35 non-neoplastic lesions. Among the analyzable images, the AI tool identified the three pathological classes with an overall accuracy of 91.9 % (384/418, 95 % confidence interval [CI]: 88.8 %–94.3 %). Its sensitivity and specificity for differentiating cancer was 91.8 % (212/231, 95 % CI: 87.5 %–95.0 %) and 97.3 % (182/187, 95 % CI: 93.9 %–99.1 %), respectively. Conclusions The newly developed AI system designed for endocytoscopy showed excellent specificity in identifying colorectal cancer.

Background and study aims Real-time diagnosis of colorectal polyps is needed to prevent unnecessary resection of benign polyps. The vessels in hyperplastic polyps sometimes mimic the characteristic meshed capillary network of neoplastic lesions on non-magnified narrow-band imaging (NBI). Endocytoscopy in conjunction with NBI (EC-NBI) enables more detailed vessel observation. The current study evaluated whether EC-NBI can accurately diagnose small colorectal lesions with visible vessels on non-magnified NBI. Patients and methods This retrospective study was conducted from January to December 2016. During colonoscopy, lesion images were obtained using NBI and EC-NBI. On EC-NBI, lesions were classified as having “clear,” “unclear,” or “invisible” blood vessel margins. All specimens were resected and pathologically examined, and the association between vessel margin findings and pathological diagnosis was assessed. The lesion surface to vessel depth was measured in clear, unclear, and invisible lesions. Results Among 114 adenomas, 108 were clear, while six were unclear. Among 36 hyperplastic polyps, eight were clear, while 28 were unclear. A micro-network (MN) pattern was seen in 106 of 114 adenomas, and four of 36 hyperplastic polyps. The sensitivity, specificity, correct diagnostic rate, and positive and negative predictive values of clear blood vessel margins or a MN pattern as an adenoma index were 98.2 %, 69.4 %, 91.3 %, 91.1 %, and 92.6 %, respectively. EC-NBI correctly diagnosed 69.4 % (25/36) of hyperplastic polyps. The lesion surface–blood vessel distance was greater in unclear versus clear lesions (P

Image-enhanced endoscopy is useful for diagnosing and identifying lesions in the gastrointestinal tract. Recently, image-enhanced endoscopy has become a breakthrough technology that has attracted significant attention. This image enhancing technology is available for capsule endoscopy, which is an effective tool for small intestinal lesions and has been applied in flexible spectral color enhancement technology and in contrast capsule like narrow-band imaging. In this field, most researchers focus on improving the visibility and detection of small intestinal lesions. This review summarizes previous studies on image-enhanced capsule endoscopy and aims to evaluate the efficacy of this technology.

This Letter presents a stable polyp-scene classification method with low false positive (FP) detection. Precise automated polyp detection during colonoscopies is essential for preventing colon-cancer deaths. There is, therefore, a demand for a computer-assisted diagnosis (CAD) system for colonoscopies to assist colonoscopists. A high-performance CAD system with spatiotemporal feature extraction via a three-dimensional convolutional neural network (3D CNN) with a limited dataset achieved about 80% detection accuracy in actual colonoscopic videos. Consequently, further improvement of a 3D CNN with larger training data is feasible. However, the ratio between polyp and non-polyp scenes is quite imbalanced in a large colonoscopic video dataset. This imbalance leads to unstable polyp detection. To circumvent this, the authors propose an efficient and balanced learning technique for deep residual learning. The authors’ method randomly selects a subset of non-polyp scenes whose number is the same number of still images of polyp scenes at the beginning of each epoch of learning. Furthermore, they introduce post-processing for stable polyp-scene classification. This post-processing reduces the FPs that occur in the practical application of polyp-scene classification. They evaluate several residual networks with a large polyp-detection dataset consisting of 1027 colonoscopic videos. In the scene-level evaluation, their proposed method achieves stable polyp-scene classification with 0.86 sensitivity and 0.97 specificity.

Background and study aims Traversing the ileocecal valve (ICV) is technically challenging with a retrograde approach to single-balloon enteroscopy (SBE). A novel technique called responsive insertion technology (RIT) colonoscopy was developed to obtain a higher cecal intubation rate in this setting. A prototype long SBE equipped with RIT (P-SBE) was developed to obtain superior insertability. The aim of this study was to compare the insertability of a standard single-balloon enteroscope (S-SBE) versus a P-SBE. Patients and methods This study was a multicenter, randomized, non-blinded, trial of 62 patients with small bowel pathologies. All procedures were performed with SBE via the trans-anal route. Procedure success was defined as stable intubation of the terminal ileum (TI) 20 cm beyond the ICV. The primary variable was time to reach stable TI intubation 20 cm beyond the ICV (TSTII). If stable TI intubation was not achieved within 10 minutes, the initial SBE was removed through the indwelling overtube and replaced with another SBE. Results Sixty patients were examined with two patients excluded from this study. TSTII using P-SBE was significantly decreased compared to S-SBE (mean P-SBE vs S-SBE: 98.3 vs 169.4 second, P = 0.006). The completion rates for stable intubation within 10 minutes of using P-SBE and S-SBE were 96.8 % and 86.2 %, respectively (P = 0.19). On endoscope replacement, all patients had achieved stable TI intubation. Conclusions SBE with RIT improves insertability when traversing the ileocecal valve in retrograde SBE.

Background and study aims Gastrointestinal neuroendocrine tumors (NET) are generally submucosal in location. Because these tumors are covered with normal mucosa, biopsy is necessary to confirm histological diagnosis before treatment. We explored the diagnostic capabilities of the endocytoscope, which can perform ultra-high magnification in vivo, for staining and diagnosing submucosal tumors in situ.

Background and study aims Mucosal healing is a current treatment target in ulcerative colitis (UC), while histological remission is another target. The aim of this study was to evaluate the efficiency of magnified narrow band imaging (NBI) findings of mucosal healing and their relationship with histological activity and prognosis. Patients and methods Patients with UC who underwent total colonoscopy between January 2010 and December 2012 with left-sided or total-colitis type UC and achieved clinical remission with an endoscopic Mayo score of 0 or 1 were included. Each colon section was observed with white light and magnified NBI, with the colonoscopy being repeated at 1-year follow-up. We assessed the relationships of magnified NBI with histological disease activity and prognosis. Magnified NBI findings were divided into three categories; honeycomb-like blood vessels (BV-H), blood vessels shaped like bare branches (BV-BB), and blood vessels shaped like vines (BV-V). Results Fifty-two patients were included. The percentage of remitted mucosa with BV-BB was 37 %, while that of mucosa with scars with BV-H was 35 %. BV-H and BV-BB did not show pathological activity (12/292 and 8/299, respectively), while BV-V showed high pathological activity (27/33, 81 %). There was a correlation between magnified NBI findings and pathological findings (P

Background and study aims Capsule endoscopy (CE) has become a routine means of diagnosing obscure gastrointestinal bleeding (OGIB) in the small intestine. Capsules using novel blue-enhanced white light-emitting diodes are expected to acquire clearer contrast images (CIs) of the small bowel vasculature. We conducted a pilot study to examine whether CIs facilitate visualization of small bowel erosions, ulcers, and areas of angioectasia compared with standard white light images (WLIs). Patients and methods A total of 24 patients with OGIB were recruited in this study. The main outcome measure was visibility of lesions on CIs compared with WLIs. We also examined the color difference between lesions and normal mucosa (ΔE) with each imaging modality. Results Three experienced physicians retrospectively evaluated 138 images of small bowel lesions (107 erosions, or ulcers, and 31 areas of angioectasia) obtained from 24 CE examinations. The endoscopists judged that compared with WLIs, CIs afforded easier identification of erosions or ulcers in 29 of 107 cases (27.1 %), were non-inferior in 68 of 107 cases (63.6 %), and were inferior in 10 of 107 cases (9.3 %). Identification of angioectasia was judged to be easier with CIs in 15 of 31 cases (48.4 %), non-inferior in 13 of 31 cases (41.9 %), and inferior in 3 of 31 cases (9.7 %). ΔE was significantly higher for CIs than WLIs, especially for angioectasia, potentially explaining why lesions were easier to visualize. Conclusions CIs obtained by CE appear to facilitate identification of small bowel erosions, ulcers, and areas of angioectasia compared with WLIs.

Background and study aims Recent studies that used magnifying chromoendoscopy and endocytoscopy (EC) to investigate endoscopic features of sessile serrated adenoma/polyps (SSA/Ps) suggested that a dilated crypt opening was an important indicator of SSA/Ps. However, no studies to date have measured the actual extent of dilatation. Hence, we investigated retrospectively the luminal areas using EC to determine a cutoff value for differentiating SSA/Ps from hyperplastic polyps (HPs). Patients and methods A total of 101 lesions, including 25 SSA/Ps, 66 HPs, and 10 normal mucosal samples, assessed by an integrated-type EC were collected. For each lesion, 1 image that showed the widest lumen was selected and the average area of the contiguous 3 lumens were calculated. The cutoff value differentiating SSAPs from HPs was determined by receiver operating curve (ROC) analysis. Results The mean luminal areas of SSA/Ps and HPs were 4152 μm2 and 2117 μm2, respectively. ROC analysis found that a luminal area cutoff of 3068 μm2 had a sensitivity of 80.0 %, a specificity of 77.3 %, an accuracy of 78.0 %, and an area under the ROC curve of 0.865. Furthermore, a cutoff of ≥ 556 μm2 was found to accurately distinguish between HPs and normal mucosa (sensitivity 98.5 %, specificity 100 %, accuracy 98.7 %, and AUC 0.998). Conclusions EC analysis of the luminal area is useful for differentiating between SSAPs and HPs. This approach could be adapted for computer-aided diagnosis of SSA/P.

Background and study aims Patients undergoing bowel preparation for colonoscopy are at risk of potentially severe adverse events such as large-bowel obstruction (LBO) and perforation. These patients usually need emergency surgery and the consequences may be fatal. Little is known about the risk factors for LBO and perforation in these circumstances. We sought to establish the natural history of LBO and perforation caused by oral preparation for colonoscopy. Patients and methods We retrospectively analyzed data from 20 patients with LBO or perforation associated with oral preparation for colonoscopy. All patients were treated at the Showa University Northern Yokohama Hospital (SUNYH) between April 2001 and December 2015. Drugs used for bowel preparation, age, sex, indication for colonoscopy, pathogenesis and treatment were recorded. Results Eighteen of the patients had LBO and 2 had perforation. Fourteen events occurred at SUNYH, which accounted for 0.016 % of patients who underwent bowel preparation during this period. Seventeen patients were symptomatic when the decision to undertake colonoscopy was made (including 7 who complained of constipation and 4 who complained of abdominal pain; 3e were asymptomatic). Nineteen patients ultimately required surgery, 13 within 3 days of presentation. Eleven patients ultimately required colostomy. There was no perioperative mortality in our cases. Conclusion Large bowel obstruction and perforation are rare events associated with oral preparation for colonoscopy, but frequently require surgery. Exacerbation of constipation might be a risk factor for LBO or perforation. Potentially catastrophic situations can be avoided by early detection and treatment.

Background and study aims: Magnifying narrow-band imaging (NBI) is useful for examination of colorectal lesions, and endocytoscopy (EC) allows diagnostic evaluation of structural atypia, nuclear atypia, and vascular structures of colorectal tumors. The aim of this study was to examine surface microvessels in deep invasive colorectal cancer using EC with a new NBI video processor system. Patients and methods: We retrospectively assessed 132 colorectal neoplastic lesions: 81 adenomas, 18 intramucosal cancers, 4 submucosal slightly invasive cancers, and 29 submucosal deep invasive cancers. Detailed vascular findings commonly seen in submucosal deep invasive carcinomas included > 2-fold vasodilatation seen in adenomas, abnormal tortuosity and branching, loss of the micro-network pattern, caliber change in > 2 places in a single blood vessel, and blood vessels not visible in a line because they appear like a string of beads (beaded sign). Results: Univariate analysis revealed 4 vascular findings that were strongly predictive of submucosal deep invasion: vasodilatation (odds ratio [OR] 9.31; 95 % confidence interval [CI] 3.57 – 24.30), loss of the micro-network pattern (OR 61.60; 95 % CI 17.87 – 212.29), caliber change (OR 35.7; 95 % CI 9.16 – 139.14), and the beaded sign (OR 45.90; 95 % CI 5.50 – 382.73). Conclusions: Detailed assessment of ultra-magnified microvessels could improve the diagnostic performance for submucosal deep invasive cancer. Study registration: UMIN-CTR000014033

Background and study aims: Gastric neuroendocrine tumors (NETs) are rare lesions that develop from neuroendocrine cells. NETs are classified into 3 types based on the rate of mitosis and Ki-67 labeling index; the NET G1 type is synonymously referred to as carcinoid. Gastric NETs are usually discovered as submucosal tumors during upper gastrointestinal endoscopic examination. This study reports a rare case of pedunculated gastric NET. The lesion was found as a result of gastroendoscopy. The gastric lesion was a pedunculated polyp with a reddish head. We performed endoscopic submucosal dissection and an en-bloc resection of the gastric lesion. The resected specimen was evaluated histopathologically and diagnosed as a carcinoid (NET G1).

Background and aim: Permeation of a vein or lymphatic vessel by a tumor is a key risk factor for lymph node metastasis. We examined the features of colorectal tumor vessel permeation using endocytoscopy, an ultra-high magnifying endoscopic system combined with a narrow-band imaging capability (EC-NBI). Patients and methods: We examined 188 colorectal lesions using EC-NBI before treatment was started. We measured the diameters of tumor vessels on EC-NBI images. We used the tumor vessel diameter (the mean diameter of four tumor-associated vessels) and the variation in tumor vessel caliber (the difference between the maximum and minimum diameters of the vessels expressed as a proportion) to judge changes in vessel formation. We examined the relationship between these variables and the extent of venous or lymphatic vessel permeation (vessel invasion) established by immunohistochemical examination of the resected specimen using monoclonal antibodies against the CD34 and D2 – 40 antigens. We also analyzed the relationships between tumor vessel diameter, tumor vessel caliber variation, and depth of tumor invasion. Results: There were significant differences in tumor vessel diameter and caliber variation between tumors in situ and T1 – T3 carcinomas. In T1 carcinomas, larger tumor vessel diameter and greater tumor vessel caliber variation were significantly associated with venous permeation. In T2 and T3 carcinomas, greater tumor vessel caliber variation was significantly associated with venous permeation. Conclusions: The vessel diameter and caliber variation of colorectal tumor microvasculature are associated with depth of invasion and venous permeation, especially in T1 carcinomas.

Schwannomas in the lateral pelvic space are very rare. Here, we report the case of a 48-year-old woman who had a tumor detected in her abdomen by abdominal ultrasonography. Abdominal computed tomography and magnetic resonance imaging revealed a well-defined solid tumor of 65 mm in diameter in the right lateral pelvic space. We performed laparoscopic surgery under a diagnosis of a gastrointestinal tumor or neurogenic tumor. The tumor was safely dissected and freed from the surrounding tissues using sharp and blunt maneuvers. The tumor originated from the right sciatic nerve. Complete laparoscopic extirpation was performed with preservation of the right sciatic nerve. Pathological examination suggested schwannoma. The patient recovered well but had remaining sciatic nerve palsy in her right foot. Laparoscopic extirpation for a schwannoma in the lateral pelvic space was safe and feasible due to the magnified surgical field afforded by laparoscopy.

A 58-year-old woman presented to her physician with rectal bleeding and intermittent diarrhea. Optical colonoscopy revealed a bulky tumor which was diagnosed as rectal cancer. She was referred to our institution for further evaluation and treatment. Slim optical colonoscopy showed an obstructive cancer in the rectosigmoid junction and no information of the proximal side of the obstruction. The patient then underwent computed tomographic (CT) colonography for further evaluation of the proximal side. Three-dimensional endoluminal ‘fly-through’ images revealed another protruded lesion in the proximal side of the obstruction. Diagnosis of synchronous double cancer was made by CT colonography. This CT data was not only used to create three-dimensional images but also to decide on a preoperative clinical staging. Laparoscopy-assisted high anterior resection was performed and T3 rectal cancer and T1 sigmoid colon cancer were confirmed in the resected specimen. Follow-up optical colonoscopy revealed no other tumors. CT colonography has recently become a popular preoperative examination tool with significant improvement in quality of image due to a rapid progress in computer technology. CT colonography correctly showed synchronous double cancer in our case and provided crucial information for planning surgery. We recommend that CT colonography should be used for evaluating the proximal side of obstructive colorectal cancer.

Background. Bile juice plays a major role in duodenogastroesophageal reflux (DGERD). Several devices to directly measure the bile concentration have been proposed. We aimed to ex-vivo evaluate the bile concentration by narrow band imaging (NBI). Method. From six surgical cholecystectomies, the content of the gallbladders was aspirated and the total biliary acid (TBA) concentration was evaluated. 2 mL was employed for serial twofold dilutions. Each dilution was scoped. Images on white light (WL) and NBI were captured and grouped accordingly to NBI-appearance and TBA-concentration. Results. Nondiluted bile had a TBA-concentration of 61965 ± 32989 μmol/L. Final dilution (1 : 4096) had 1.16 μmol/L. NBI and correspondent WL images were grouped into seven groups, and an NBI/Bile scale was created. Conclusion. The scale showed that not only NBI scale but also white light scale could be useful to predict the bile concentration. This initial study shows that NBI has a potential role in the detection of DGERD and further investigation is warranted to distinguish the presence and the concentration of bile, especially at very low TBA concentrations.

Background: The histopathology of the muscularis propria (MP) is unknown in patients with achalasia. Endocytoscopy (EC) was developed as an ultra-high magnification endoscopy, and the submucosal tunnel created during peroral endoscopic myotomy (POEM) not only provides access to the MP but also enables subsequent endoscopic assessment of the MP. Patients and methods: In seven patients with achalasia (mean ± SD; 35 ± 18.1 years; men:women, 4:3) who underwent POEM (myotomy length: 12 ± 2.2 cm), subsequent EC examination was performed from the mid-esophagus to the gastric side. EC images were compared to the results of histopathologic examination (two biopsies from the mid-esophagus and lower esophageal sphincter), which was the standard. Results: In all patients, favorable EC images were obtained, and spindle-shaped smooth muscle cells were detected. In our series, we observed no notable features such as atrophy or hypertrophy of smooth muscle cells. In addition, the EC assessment was consistent with the results of biopsy. No complications were encountered during any of the procedures. Conclusion: In a clinical setting, real-time assessment of the MP using EC is feasible. This technique may play an important role in determining the pathology of achalasia and other diseases that affect gastrointestinal function.

Background. Standard treatment of early gastric cancer (EGC) after endoscopic resection with risk factors of nodal metastases and incomplete resection is controversial. We investigated optimal management for the patients with potentially noncurative EGC after endoscopic resection. Methods. We retrospectively examined clinicopathological data and surgical outcomes of all patients with clinically solitary gastric adenocarcinoma who underwent curative surgery after a single peroral endoscopic resection at the Digestive Disease Center of Showa University Northern Yokohama Hospital between April 2001 and December 2012. Fisher's exact test was used for univariate analysis. For multivariate analysis, stepwise multiple linear regression was used to identify independent predictors related to lymph node metastasis and remnant of primary tumor. Results. A total of 41 patients were studied. Four patients (9.8%) had lymph node metastases. Primary tumors remained in 6 patients (14.6%). Only venous invasion was statistically significant to lymph node metastasis (P=0.017). With respect to remnant of the primary tumor, pT1b2 tumor invasion (P=0.015) and horizontal margin (P=0.013) were statistically significant. Conclusions. Surgery with limited lymphadenectomy is recommended for tumors with venous invasion or pT1b2 tumor invasion, and additional endoscopic resection may be allowed for tumors with horizontal involvement.

Background. This study addresses clinicopathological differences between patients with gastric cardia and subcardial cancer with and without esophagogastric junctional invasion. Methods. We performed a single-center, retrospective cohort study. We studied patients who underwent curative surgery for gastric cardia and subcardial cancers. Tumors centered in the proximal 5 cm of the stomach were classed into two types, according to whether they did (Ge) or did not (G) invade the esophagogastric junction. Results. A total of 80 patients were studied; 19 (73.1%) of 26 Ge tumors and 16 (29.6%) of 54 G tumors had lymph nodes metastases. Incidence of nodal metastasis in pT1 tumors was significantly higher in the Ge tumor group. No nodal metastasis in cervical lymph nodes was recognized. Only two patients with Ge tumors had mediastinal lymph node metastases. Incidence of perigastric lymph node metastasis was significantly higher in those with Ge tumors. Ge tumors tended to be staged as progressive disease using the esophageal cancer staging manual rather than the gastric cancer staging manual. Conclusion. Because there are some differences in clinicopathological characteristics, it is thought to be adequate to distinguish type Ge from type G tumor.

Background and Aim. We evaluated the usefulness of background coloration (BC), a color change in the area between intrapapillary capillary loops (IPCLs) in the early esophago-pharyngeal lesions using NBI with magnificaiton. Methods. Between April 2004 and March 2010, a total of 294 esophago-pharyngeal lesions were examined using NBI with magnification, and the presence of BC and IPCL patterns were assessed. Using BC, discrimination of squamous cell carcinoma (SCC) or high-grade neoplasia (HGN) from low-grade neoplasia (LGN) or nonatypia was conducted. Results. Among 294 lesions, 209 lesions (71.1%) were positive for BC, while 85 (28.9%) were negative. In the BC-positive group, 187 lesions (89.5%) were diagnosed as SCC/HGN. And 68 lesions (80.0%) in the BC-negative group were diagnosed as LGN/nonatypia. Overall accuracy of BC to discriminate SCC/HGN from LGN/nonatypia was 87.3%. The sensitivity and specificity were 91.9%, 76.7%. BC could discriminate SCC/HGN from LGN/nonatypia accurately (P

Background. Although it is possible to visualize gastrointestinal stromal tumors (GIST) of the stomach by endoscopy, their pretreatment histological diagnosis is often difficult. The aim of this study was to investigate predictors of accurate preoperative pathological diagnosis of gastric GIST. Material and Methods. We retrospectively studied patients with gastric GIST who had undergone pretreatment endoscopic biopsy and surgery, and examined their clinicopathological data. Results. Twenty-three patients were eligible. Thirty-four endoscopic biopsies (mean 2.6, range 1–8) were obtained. Preoperative pathological diagnoses of GIST were made in 18 patients. Precise diagnoses were made in 18 (52.9%) of the 34 biopsies. Endoscopic ultrasound (EUS) resulted in precise diagnoses in 11 (91.7%) of the 12 biopsy specimens. Fine-needle aspiration (FNA) biopsy resulted in precise diagnoses in 11 (84.6%) of the 13 biopsy specimens. The accuracy of pathological diagnosis by EUS-guided FNA biopsy was 100%. The procedure of EUS-guided FNA biopsy had no complications or recurrent disease. In a multivariate analysis, only EUS achieved a significantly superior rate of diagnosis (odds ratio, 11.884; 95% confidence interval, 1.204–289.230; P=0.034). Conclusion. EUS-guided FNA biopsy is the most accurate for pretreatment pathological diagnosis of gastric GIST and for prevention of both of early complications and disease recurrence.

Objective: To develop and externally validate an updated artificial intelligence (AI) prediction system for stratifying the risk of lymph node metastasis (LNM) in T2 colorectal cancer (CRC). Background: Recent technical advances allow complete local excision of T2 CRC, traditionally treated with surgical resection. Yet, the widespread adoption of this approach is hampered by the inability to stratify the risk of LNM. Methods: Data from patients with pT2 CRC undergoing surgical resection between April 2000 and May 2022 at one Japanese and one Italian center were analyzed. Primary goal was AI system development for accurate LNM prediction. Predictors encompassed 7 variables: age, sex, tumor size, tumor location, lymphovascular invasion, histologic differentiation, and carcinoembryonic antigen level. The tool's discriminating power was assessed through area under the curve, sensitivity, and specificity. Results: Out of 735 initial patients, 692 were eligible. Training and validation cohorts comprised of 492 and 200 patients, respectively. The AI model displayed an area under the curve of 0.75 in the combined validation data set. Sensitivity for LNM prediction was 97.8%, and specificity was 15.6%. The positive and the negative predictive value were 25.7% and 96%, respectively. The false negative rate was 2.2%, and the false positive was 84.4%. Conclusions: Our AI model, based on easily accessible clinical and pathologic variables, moderately predicts LNM in T2 CRC. However, the risk of false negative needs to be considered. The training of the model including more patients across western and eastern centers -- differentiating between colon and rectal cancers -- may improve its performance and accuracy. [ABSTRACT FROM AUTHOR]