Performance evaluation of a computer-aided polyp detection system with artificial intelligence for colonoscopy.

OBJECTIVES: A computer-aided detection (CAD) system was developed to support the detection of colorectal lesions by deep learning using video images of lesions and normal mucosa recorded during colonoscopy. The study's purpose was to evaluate the stand-alone performance of this device under blinded conditions. METHODS: This multicenter prospective observational study was conducted at four Japanese institutions. We used 326 videos of colonoscopies recorded with patient consent at institutions in which the Ethics Committees approved the study. The sensitivity of successful detection of the CAD system was calculated using the target lesions, which were detected by adjudicators from two facilities for each lesion appearance frame; inconsistencies were settled by consensus. Successful detection was defined as display of the detection flag on the lesion for more than 0.5 s within 3 s of appearance. RESULTS: Of the 556 target lesions from 185 cases, detection success sensitivity was 97.5% (95% confidence interval [CI] 95.8-98.5%). The "successful detection sensitivity per colonoscopy" was 93% (95% CI 88.3-95.8%). For the frame-based sensitivity, specificity, positive predictive value, and negative predictive value were 86.6% (95% CI 84.8-88.4%), 84.7% (95% CI 83.8-85.6%), 34.9% (95% CI 32.3-37.4%), and 98.2% (95% CI 97.8-98.5%), respectively. TRIAL REGISTRATION: University Hospital Medical Information Network (UMIN000044622).

Endoscopic Removal of Premalignant Lesions Reduces Long-Term Colorectal Cancer Risk: Results From the Japan Polyp Study.

BACKGROUND & AIMS: To date, no regional evidence of long-term colorectal cancer (CRC) risk reduction after endoscopic premalignant lesion removal has been established. We aimed to analyze this over a long-term follow-up evaluation. METHODS: This was a prospective cohort study of participants from the Japan Polyp Study conducted at 11 Japanese institutions. Participants underwent scheduled follow-up colonoscopies after a 2-round baseline colonoscopy process. The primary outcome was CRC incidence after randomization. The observed/expected ratio of CRC was calculated using data from the population-based Osaka Cancer Registry. Secondary outcomes were the incidence and characteristics of advanced neoplasia (AN). RESULTS: A total of 1895 participants were analyzed. The mean number of follow-up colonoscopies and the median follow-up period were 2.8 years (range, 1-15 y) and 6.1 years (range, 0.8-11.9 y; 11,559.5 person-years), respectively. Overall, 4 patients (all males) developed CRCs during the study period. The observed/expected ratios for CRC in all participants, males, and females, were as follows: 0.14 (86% reduction), 0.18, and 0, respectively, and 77 ANs were detected in 71 patients (6.1 per 1000 person-years). Of the 77 ANs detected, 31 lesions (40.3%) were laterally spreading tumors, nongranular type. Nonpolypoid colorectal neoplasms (NP-CRNs), including flat (<10 mm), depressed, and laterally spreading, accounted for 59.7% of all detected ANs. Furthermore, 2 of the 4 CRCs corresponded to T1 NP-CRNs. CONCLUSIONS: Endoscopic removal of premalignant lesions, including NP-CRNs, effectively reduced CRC risk. More than half of metachronous ANs removed by surveillance colonoscopy were NP-CRNs. The Japan Polyp Study: University Hospital Medical Information Network Clinical Trial Registry: University Hospital Medical Information Network Clinical Trial Registry, C000000058; cohort study: UMIN000040731.

Clinical Guidelines for Diagnosis and Management of Cowden Syndrome/PTEN Hamartoma Tumor Syndrome in Children and Adults-Secondary Publication.

Cowden syndrome (CS)/PTEN hamartoma tumor syndrome (PHTS) is a rare autosomal dominantly inherited condition caused by germline pathogenesis. It is associated with multiple hamartomatous lesions occurring in various organs and tissues, including the gastrointestinal tract, skin, mucous membranes, breast, thyroid, endometrium, and brain. Macrocephaly or multiple characteristic mucocutaneous lesions commonly develop in individuals in their 20s. This syndrome is occasionally diagnosed in childhood due to the occurrence of multiple gastrointestinal polyps, autism spectrum disorders, and intellectual disability. CS/PHTS can be diagnosed taking the opportunity of multigene panel testing in patients with cancer. Appropriate surveillance for early diagnosis of associated cancers is required because patients have a high risk of cancers including breast, thyroid, colorectal, endometrial, and renal cancers. Under these circumstances, there is growing concern regarding the management of CS/PHTS in Japan, but there are no available practice guidelines. To address this situation, the guideline committee, which included specialists from multiple academic societies, was organized by the Research Group on Rare and Intractable Diseases granted by the Ministry of Health, Labour, and Welfare, Japan. The present clinical guidelines explain the principles in the diagnosis and management of CS/PHTS, together with four clinical questions and the corresponding recommendations, incorporating the concept of the Grading of Recommendations Assessment, Development, and Evaluation system. Herein, we present an English version of the guideline, some of which have been updated, to promote seamless implementation of accurate diagnosis and appropriate management of pediatric, adolescent, and adult patients with CS/PHTS.

Risk factors for vertical incomplete resection in endoscopic submucosal dissection of deep invasive submucosal colorectal cancer.

INTRODUCTION: It has been recently reported that deep invasive submucosal (T1b) colorectal cancer (CRC) without other pathological risk factors for lymph node metastasis has a low rate of lymph node metastasis, increasing the possibility of endoscopic submucosal dissection (ESD) in the future. However, ESD for T1b CRC is technically difficult, and some lesions cannot be resected en bloc. This study aimed to identify the risk factors associated with vertical incomplete ESD in T1b CRC. METHODS: We retrospectively studied 140 pathological T1b CRC lesions that underwent initial ESD at our institution between January 2011 and October 2020, and categorized them into positive vertical margin (PVM) and negative vertical margin (NVM) groups. The risk factors for PVM were examined using univariate and multivariate analyses, and a subgroup analysis for T1b CRC with an obvious depressed surface was performed. RESULTS: Multivariate analysis revealed obvious depression (hazard ratio [HR]: 7.4; 95% confidence interval [CI]: 2.47-22.5) and severe fibrosis (HR: 11.4; 95% CI: 3.95-33.0) as significant risk factors for PVM. Length of depressed surface ≥12 mm (HR: 6.19; 95% CI: 1.56 -24.6) was identified as an independent predictor of PVM for T1b CRC with an obvious depression. CONCLUSION: Pathological T1b CRC cases with an obvious depression and severe fibrosis are at a high risk of vertical incomplete ESD.

Guidelines for Colorectal Cold Polypectomy (supplement to "Guidelines for Colorectal Endoscopic Submucosal Dissection/Endoscopic Mucosal Resection").

The Japan Gastroenterological Endoscopy Society published the second edition of the "Guidelines for Colorectal Endoscopic Submucosal Dissection/Endoscopic Mucosal Resection" in 2019 to clarify the indications for colorectal endoscopic mucosal resection (EMR) and endoscopic submucosal dissection and to ensure appropriate preoperative diagnoses as well as effective and safe endoscopic treatment in front-line clinical settings. Endoscopic resection with electrocautery, including polypectomy and EMR, is indicated for colorectal polyps. Recently, the number of facilities introducing and implementing cold polypectomy without electrocautery has increased. Herein, we establish supplementary guidelines for cold polypectomy. Considering that the level of evidence for each statement is limited, these supplementary guidelines must be verified in clinical practice.

Training program using a traction device improves trainees' learning curve of colorectal endoscopic submucosal dissection.

BACKGROUND: Colorectal endoscopic submucosal dissection (ESD) requires advanced endoscopic skill. For safer and more reliable ESD implementation, various traction devices have been developed in recent years. The purpose of this research was to evaluate whether an ESD training program using a traction device (TD) would contribute to the improvement of trainees' skill acquisition. METHODS: The differences in treatment outcomes and learning curves by the training program were compared before and after the introduction of TD (control group: January 2014 to March 2016; TD group: April 2016 to June 2018). RESULTS: A total of 316 patients were included in the analysis (TD group: 202 cases; control group: 114 cases). The number of cases required to achieve proficiency in ESD techniques was 10 in the TD group and 21 in the control group. Compared to the control group, the TD group had a significant advantage in ESD self-completion rate (73.8% vs. 58.8%), dissection speed (19.5 mm2/min vs. 15.9 mm2/min), en bloc resection rate (100% vs. 90%), and R0 resection rate (96% vs. 83%). CONCLUSIONS: The rate of colorectal ESD self-completion by trainees improved immediately after the start of the training program using a traction device compared to the conventional method, and the dissection speed tended to increase linearly with ESD experience. We believe that ESD training using a traction device will help ESD techniques to be performed safely and reliably among trainees.

Outcomes of endoscopic submucosal dissection for colorectal neoplasms: Prospective, multicenter, cohort trial.

OBJECTIVES: Endoscopic mucosal resection (EMR) is the gold standard for the treatment of noninvasive large colorectal lesions, despite challenges associated with nonlifting lesions and a high rate of local recurrence. Endoscopic submucosal dissection (ESD) offers the possibility of overcoming these EMR limitations. However, a higher risk of complications and longer procedure time prevented its dissemination. As ESD now provides more stable results because of standardized techniques compared with those used earlier, this study aimed to quantify the rates of en bloc and curative resections, as well as ESD complications, in the present situation. METHODS: A multicenter, large-scale, prospective cohort trial of ESD was conducted at 20 institutions in Japan. Consecutive patients scheduled for ESD were enrolled from February 2013 to January 2015. RESULTS: ESD was performed for 1883 patients (1965 lesions). The mean procedure time was 80.6 min; en bloc and curative resections were achieved in 1759 (97.0%) and 1640 (90.4%) lesions, respectively, in epithelial lesions ≥20 mm. Intra- and postprocedural perforations occurred in 51 (2.6%) and 12 (0.6%) lesions, respectively, and emergency surgery for adverse events was performed in nine patients (0.5%). CONCLUSIONS: This trial conducted after the standardization of the ESD technique throughout Japan revealed a higher curability, shorter procedure time, and lower risk of complications than those reported previously. Considering that the target lesions of ESD are more advanced than those of EMR, ESD can be a first-line treatment for large colorectal lesions with acceptable risk and procedure time. (Clinical Trial Registration: UMIN000010136).

Evidence-based clinical practice guidelines for management of colorectal polyps.

BACKGROUND: The Japanese Society of Gastroenterology (JSGE) published ''Daicho Polyp Shinryo Guideline 2014'' in Japanese and a part of this guideline was published in English as "Evidence-based clinical practice guidelines for management of colorectal polyps" in the Journal of Gastroenterology in 2015. A revised version of the Japanese-language guideline was published in 2020, and here we introduce a part of the contents of revised version. METHODS: The guideline committee discussed and drew up a series of clinical questions (CQs). Recommendation statements for the CQs were limited to items with multiple therapeutic options. Items with established conclusions that had 100% agreement with previous guidelines (background questions) and items with no (or old) evidence that are topics for future research (future research questions: FRQs) were given descriptions only. To address the CQs and FRQs, PubMed, ICHUSHI, and other sources were searched for relevant articles published in English from 1983 to October 2018 and articles published in Japanese from 1983 to November 2018. The Japan Medical Library Association was also commissioned to search for relevant materials. Manual searches were performed for questions with insufficient online references. RESULTS: The professional committee created 18 CQs and statements concerning the current concept and diagnosis/treatment of various colorectal polyps, including their epidemiology, screening, pathophysiology, definition and classification, diagnosis, management, practical treatment, complications, and surveillance after treatment, and other colorectal lesions (submucosal tumors, nonneoplastic polyps, polyposis, hereditary tumors, ulcerative colitis-associated tumors/carcinomas). CONCLUSIONS: After evaluation by the moderators, evidence-based clinical practice guidelines for management of colorectal polyps were proposed for 2020. This report addresses the therapeutic related CQs introduced when formulating these guidelines.

Malignant potential of colorectal neoplasms in Lynch syndrome: an analysis of 325 lesions endoscopically treated at a single institute.

BACKGROUND: Patients with Lynch syndrome are at an increased risk of developing colorectal cancer, and the adenoma-carcinoma sequence is accelerated in these patients. However, the clinicopathological characteristics of colorectal neoplasms in Lynch syndrome patients are not well-known. METHODS: A total of 325 consecutive colorectal neoplasms were endoscopically removed from 68 patients with Lynch syndrome between June 2005 and May 2018 and retrospectively reviewed. RESULTS: Of the 325 lesions, 94 (29%), 220 (68%) and 11 (3%) were from patients with MLH1, MSH2 and MSH6 mutations, respectively. The median lesion size was 5 mm (range 2-40 mm), with 229 (71%) lesions having a non-polypoid morphology. The frequencies of advanced neoplasms, including high-grade adenomas, intramucosal carcinomas and submucosal invasive carcinomas were 14, 34, 97 and 93% for lesions with diameters of <5, ≥5 and <10, ≥10 and <20, and ≥20 mm, respectively. The frequencies of advanced neoplasms in the proximal colon, distal colon and rectum did not significantly differ (36, 35 and 41%, respectively). CONCLUSIONS: Our results suggest that the malignant transformation interval from low-grade adenomas to advanced neoplasms is similar in all parts of the colon. Furthermore, since one-third of neoplastic lesions with diameters of ≥5 and <10 mm and most of those ≥10 mm were advanced neoplasms, we recommend that in Lynch syndrome patients, careful colonoscopic surveillance should be performed throughout the colon, and all neoplastic lesions, regardless of the size, should be subjected to detailed endoscopic examination, complete resection and detailed pathological examination.

Adding Narrow-Band Imaging to Chromoendoscopy for the Evaluation of Tumor Response to Neoadjuvant Therapy in Rectal Cancer.

BACKGROUND: Endoscopic assessment is crucial in diagnosing clinical complete response after neoadjuvant therapy in rectal cancer. OBJECTIVE: The purpose of this research was to evaluate the benefits of adding narrow-band imaging endoscopy to conventional chromoendoscopy in predicting pathologic complete response in the surgical specimen. DESIGN: This was a prospective nonrandomized study. SETTINGS: This was an ad hoc study of a prospective phase II trial at a single comprehensive cancer center that evaluated oncologic outcomes of a neoadjuvant therapy for rectal cancer. PATIENTS: Patients with high-risk stage II to III low rectal cancer who received neoadjuvant modified folinic acid, fluorouracil, and oxaliplatin plus bevacizumab followed by chemoradiotherapy and surgery were included. INTERVENTION: Tumor response after neoadjuvant therapy was evaluated using conventional white light endoscopy plus chromoendoscopy then followed by using narrow-band imaging based on a predefined diagnostic protocol. MAIN OUTCOME MEASURES: Diagnostic accuracy for predicting pathologic complete response and inter-rater agreement between an expert and trainee endoscopists were compared between the assessments using conventional white light endoscopy plus chromoendoscopy and the assessment adding narrow-band imaging. RESULTS: In total, 61 patients were eligible for the study, and 19 had pathologic complete response (31.1%). Although the addition of narrow-band imaging correctly converted the diagnosis in 3 patients, overall diagnostic improvement in predicting pathologic complete response was limited (conventional chromoendoscopy vs adding narrow-band imaging: accuracy, 70.5% vs 75.4%; sensitivity, 63.2% vs 73.7%; specificity, 73.8% vs 76.2%; positive predictive value, 52.2% vs 58.3%; and negative predictive value, 81.6% vs 86.5%). A κ value for the inter-rater agreement improved from 0.599 to 0.756 by adding narrow-band imaging. LIMITATIONS: This was a single-center study with a relatively small sample size. CONCLUSIONS: Despite the limited improvement in diagnostic accuracy, adding narrow-band imaging to chromoendoscopy improved inter-rater agreement between the expert and nonexpert endoscopists. Narrow-band imaging is a reliable and promising modality for universal standardization of the diagnosis of clinical complete response. See Video Abstract at http://links.lww.com/DCR/B275. ADICIÓN DE IMÁGENES DE BANDA ESTRECHA A LA CROMOENDOSCOPÍA PARA LA EVALUACIÓN DE LA RESPUESTA TUMORAL A LA TERAPIA NEOADYUVANTE EN EL CÁNCER DE RECTO: La evaluación endoscópica es fundamental para valorar la respuesta clínica completa después de la terapia neoadyuvante en el cáncer de recto.Evaluar los beneficios de agregar endoscopia de imagen de banda estrecha a la cromoendoscopía convencional para predecir la respuesta patológica completa en la muestra quirúrgica.Estudio prospectivo no aleatorizado.Un estudio ad hoc de un ensayo prospectivo de fase II en un solo centro integral de cáncer que evaluó los resultados oncológicos de una terapia neoadyuvante para el cáncer rectal.Pacientes con cáncer rectal bajo de alto riesgo en estadio II-III que recibieron ácido folínico neoadyuvante modificado, fluorouracilo y oxaliplatino más bevacizumab seguido de quimiorradioterapia y cirugía.La respuesta tumoral después de la terapia neoadyuvante se evaluó mediante endoscopia de luz blanca convencional más cromoendoscopía, seguido de imágenes de banda estrecha basadas en un protocolo de diagnóstico predefinido.La precisión diagnóstica para predecir la respuesta patológica completa y el acuerdo entre evaluadores entre un experto y un endoscopista en entrenamiento se compararon entre las evaluaciones utilizando endoscopia de luz blanca convencional más cromoendoscopía y la evaluación agregando imágenes de banda estrecha.En total, 61 pacientes fueron elegibles para el estudio, y 19 tuvieron una respuesta patológica completa (31.1%). Aunque la adición de imágenes de banda estrecha convirtió correctamente el diagnóstico en 3 pacientes, la mejora diagnóstica general en la predicción de la respuesta patológica completa fue limitada (cromoendoscopía convencional versus adición de imágenes de banda estrecha: precisión, 70.5% versus 75.4%; sensibilidad, 63.2% versus 73.7%; especificidad, 73.8% versus 76.2%; valor predictivo positivo, 52.2% versus 58.3%; y valor predictivo negativo, 81.6% versus 86.5%). Un valor de kappa para el acuerdo entre evaluadores mejoró de 0.599 a 0.756 al agregar imágenes de banda estrecha.Un estudio de centro único con un tamaño de muestra relativamente pequeño.A pesar de la mejora limitada en la precisión diagnóstica, agregar imágenes de banda estrecha a la cromoendoscopía mejoró el acuerdo entre evaluadores entre los endoscopistas expertos y no expertos. La imagenología de banda estrecha es una modalidad confiable y prometedora para la estandarización universal del diagnóstico de respuesta clínica completa. Consulte Video Resumen en http://links.lww.com/DCR/B275.

Clinical utility of the pocket-creation method with a traction device for colorectal endoscopic submucosal dissection.

BACKGROUND: Colorectal endoscopic submucosal dissection (ESD) is technically demanding while ensuring safety, especially in cases with fibrosis and/or poor maneuverability. To overcome such difficulties, we developed a novel method called the pocket-creation method with a traction device (PCM with TD). We then evaluated the effectiveness and safety of PCM with TD in colorectal ESD compared to other conventional methods. METHODS: In total, 324 colorectal lesions treated with ESD from July 2018 to June 2019 were included. The following three treatment strategies were used: conventional ESD (CE), CE with TD, and PCM with TD. Patient backgrounds and treatment outcomes were retrospectively compared and analyzed. RESULTS: As ESD methods, CE, CE with TD, and PCM with TD account for 58% (187/324), 24% (78/324), and 18% (59/324), respectively. No significant difference was observed among the three groups in en bloc and R0 resection rates or adverse events. The rate of lesions with fibrosis and poor maneuverability was significantly higher in the PCM with TD group (CE group vs CE with TD group vs PCM with TD group: fibrosis, 24% vs 47% vs 64%, p < 0.001; poor maneuverability, 5.3% vs 13% vs 20%, p = 0.002). Dissection speed was significantly higher in the PCM with TD than in the CE with TD group (p = 0.003). CONCLUSIONS: PCM with TD can achieve a stable en bloc resection rate and R0 dissection rate without adverse events even in the hands of trainees, irrespective of the size and location of the lesion, presence of fibrosis, and under poor maneuverability conditions.

Randomised comparison of postpolypectomy surveillance intervals following a two-round baseline colonoscopy: the Japan Polyp Study Workgroup.

OBJECTIVE: To assess whether follow-up colonoscopy after polypectomy at 3 years only, or at 1 and 3 years would effectively detect advanced neoplasia (AN), including nonpolypoid colorectal neoplasms (NP-CRNs). DESIGN: A prospective multicentre randomised controlled trial was conducted in 11 Japanese institutions. The enrolled participants underwent a two-round baseline colonoscopy (interval: 1 year) to remove all neoplastic lesions. Subsequently, they were randomly assigned to undergo follow-up colonoscopy at 1 and 3 years (2-examination group) or at 3 years only (1-examination group). The incidence of AN, defined as lesions with low-grade dysplasia ≥10 mm, high-grade dysplasia or invasive cancer, at follow-up colonoscopy was evaluated. RESULTS: A total of 3926 patients were enrolled in this study. The mean age was 57.3 (range: 40-69) years, and 2440 (62%) were male. Of these, 2166 patients were assigned to two groups (2-examination: 1087, 1-examination: 1079). Overall, we detected 29 AN in 28 patients at follow-up colonoscopy in both groups. On per-protocol analysis (701 in 2-examination vs 763 in 1-examination group), the incidence of AN was similar between the two groups (1.7% vs 2.1%, p=0.599). The results of the non-inferiority test were significant (p=0.017 in per-protocol, p=0.001 in intention-to-treat analysis). NP-CRNs composed of dominantly of the detected AN (62%, 18/29), and most of them were classified into laterally spreading tumour non-granular type (83%, 15/18). CONCLUSION: After a two-round baseline colonoscopy, follow-up colonoscopy at 3 years detected AN, including NP-CRNs, as effectively as follow-up colonoscopies performed after 1 and 3 years.

Predictors of invasive cancer of large laterally spreading colorectal tumors: A multicenter study in Japan.

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 < 0.001). The frequency of pathological T1 cancers was the highest at 36% of LST nongranular pseudodepressed type, followed by 14% of LST nongranular flat-elevated type, 11% of LST granular nodular mixed type, and 3% of LST granular homogenous type lesions. The risk of pathological T1 cancer was significantly associated with LST subclassification and tumor diameter. The area under the curve (AUC) was high (0.743). In the validation study, the AUC was 0.573. CONCLUSIONS: In patients with large colorectal LSTs resected endoscopically, the risk of pathological T1 cancer can be predicted on the basis of the LST subclassification and tumor diameter.

Japan Gastroenterological Endoscopy Society guidelines for colorectal endoscopic submucosal dissection/endoscopic mucosal resection.

Suitable lesions for endoscopic treatment include not only early colorectal carcinomas but also several types of precarcinomatous adenomas. It is important to establish practical guidelines wherein preoperative diagnosis of colorectal neoplasia and selection of endoscopic treatment procedures are appropriately outlined and to ensure that actual endoscopic treatment is useful and safe in general hospitals when carried out in accordance with guidelines. In cooperation with the Japanese Society for Cancer of the Colon and Rectum, the Japanese Society of Coloproctology, and the Japanese Society of Gastroenterology, the Japan Gastroenterological Endoscopy Society compiled colorectal endoscopic submucosal dissection/endoscopic mucosal resection guidelines by using evidence-based methods in 2014. The first edition of these guidelines was published 5 years ago. Accordingly, we have published the second edition of these guidelines based on recent new knowledge and evidence.

Macroscopic and microscopic morphology and molecular profiling to distinguish heterogeneous traditional serrated adenomas of the colorectum.

OBJECTIVES: Serrated lesions of the colorectum often have complex histological morphology, and some groups include subtypes with different molecular biology. This study aimed to characterize serrated lesions with heterogeneous histology that was dominated by a traditional serrated adenoma (TSA) component. METHODS: Representative lesions were selected based on both endoscopic and histological features. If a lesion had more than one component, each of the different structural parts was considered as a separate sample. DNA was extracted from 177 samples of 60 lesions and amplified to screen for BRAF and K/NRAS mutations. RESULTS: Heterogeneous TSA samples were classified into four categories: sessile serrated lesion with TSA (SA-1); TSAs with microvesicular hyperplastic polyp (SA-2); TSAs with unclassified adenoma, characterized by tubulo-serrated histology (SA-3); and TSAs with conventional adenomas (SA-4). On endoscopy, SA-1 lesions had sessile-elevated morphology with the small reddish elevations; SA-2 lesions had a pedunculated appearance with a whitish mucosal component at the stalk; SA-3 lesions had a sessile-elevated component surrounded by flat spreading margins; and SA-4 lesions had mixed adenomatous morphology. Eighteen of the 19 category SA-1 and -2 lesions (95%) had BRAF mutations, and all of the SA-3 and -4 lesions had K/NRAS mutations. CONCLUSIONS: Traditional serrated adenomas were classified into two phenotypes according to their molecular characteristics: microvesicular serrated subtypes with BRAF mutations (SA-1 and -2 lesions) and subtypes containing tubulo-serrated/conventional adenoma with K/NRAS mutations (SA-3 and -4 lesions). Each subtype had characteristic macroscopic and microscopic morphologies and was distinct on endoscopy.

Clinicopathological characteristics and frequency of multiple rectal neuroendocrine tumors: a single-center retrospective study.

BACKGROUND: Rectal multiple neuroendocrine tumors (M-NETs) are rare, with only few epidemiologic reports on the topic. Therefore, their clinicopathological features are not completely known, and the appropriate treatment strategy has not been established. PURPOSE: This study aimed to compare the clinicopathological malignant potential (lymphatic or venous invasion-positive and lymph node metastasis rates) of M-NETs with that of solitary NETs (S-NETs). METHODS: We retrospectively investigated 369 patients with NETs of the rectum. Patients who underwent colonoscopy at the Cancer Institute Hospital between January 1979 and 2016 and diagnosed with S-NETs were included, and S-NETs were found in 348 patients. Patients with M-NETs were classified into two groups as follows: patients with < 8 tumors (several (S) group, n = 21) and those with ≥ 8 tumors (numerous (N) group, n = 3). RESULTS: The overall frequency of M-NETs was 5.7% and that of the N group was 0.8%. The mean tumor diameter in the N group was 6.0 mm (range, 4-8 mm). The lymphatic invasion rates of the S-NETs, and S and N groups of the M-NETs were 8.9%, 5.6%, and 66.7%, respectively. Moreover, the lymph node metastasis rates were 9.2%, 11.1%, and 33.3, respectively. CONCLUSIONS: While M-NETs in the S and N groups had different characteristics, they were rarer in the N group. The N group may have higher rates of lymphatic invasion and lymph node metastasis regardless of tumor size.

Pathological risk factors and predictive endoscopic factors for lymph node metastasis of T1 colorectal cancer: a single-center study of 846 lesions.

BACKGROUND: Determining the depth of invasion of early stage colorectal cancer has been emphasized as a means of improving endoscopic diagnostic accuracy. Recent studies have focused on other pathological risk factors for lymph node metastasis (LNM). We investigated the significance of depth of invasion and predictive properties of other endoscopic findings. METHODS: We retrospectively investigated 846 patients with submucosal invasive (T1) colorectal cancer who received an accurate pathological diagnosis and were treated between January 2005 and December 2016. Pathological risk factors associated with LNM were reviewed. We divided patients into groups: low-risk T1 colorectal cancer (LRC; no risk factors) and high-risk T1 colorectal cancer (HRC; exhibiting lymphovascular invasion, tumor budding grade of 2/3, and/or poor differentiation) and studied predictive endoscopic factors for HRC. RESULTS: Significant risk factors for LNM in multivariate analysis were lymphovascular invasion [odds ratio (OR) 8.09; 95% confidence interval (CI) 3.84-17.1], tumor budding (OR 1.89; 95% CI 1.09-3.29), and histological differentiation (OR 2.09; 95% CI 1.12-3.89). The LNM-positive rate with only deep submucosal invasion was 1.6%. Significant predictive factors for HRC in multivariate analysis identified rectal tumor location (OR 1.92; 95% CI 1.35 -2.72, depression (OR 2.73; 95% CI 1.96 -3.80), protuberance within the depression (OR 2.58; 95% CI 1.39- 4.78), expansiveness (OR 2.39; 95% CI 1.27- 4.50), and loss of mucosal patterns (OR 1.90; 95% CI 1.20 -3.01) as significant factors. CONCLUSIONS: Rectal tumor location, depression, protuberance within the depression, expansiveness, and loss of mucosal patterns could be predictive factors for HRC.

Endoscopic criteria to evaluate tumor response of rectal cancer to neoadjuvant chemoradiotherapy using magnifying chromoendoscopy.

BACKGROUND AND AIMS: Precise endoscopic assessment of complete response to neoadjuvant chemoradiotherapy before surgery is important for optimizing surgical and non-surgical treatment. We prospectively evaluated the accuracy of the newly proposed endoscopic criteria to identify complete response, using magnifying chromoendoscopy. METHODS: New endoscopic criteria were created to define endoscopic complete response, near complete response and incomplete response, using magnifying chromoendoscopy. The criteria contained notable endoscopic findings, including shape of the scar, state of the ulcer, finding of white moss, presence of residual protruded nodules, regenerated pits of the scar, presence of neoplastic pit patterns, and extension of rectal wall. Seventy-nine patients with rectal cancer who received neoadjuvant chemoradiotherapy were prospectively evaluated 1-3 days before resection. Diagnostic accuracy to identify pathological complete response and interobserver agreement among a supervising colonoscopist and two trainees were investigated. RESULTS: Pathological complete response was obtained in 17 patients (21.5%). The diagnostic accuracy of endoscopic complete response was 85%, with a sensitivity of 47%, specificity of 97%, positive predictive value of 80% and negative predictive value of 77%. The kappa-value for interobserver agreement across 3 doctors was 0.57 (standard error, 0.74; 95% confidence interval, 0.39-0.76). CONCLUSION: The newly proposed endoscopic criteria using magnifying chromoendoscopy achieved excellent diagnostic accuracy to determine good responders to neoadjuvant chemoradiotherapy in rectal cancer, with fair interobserver agreement. The criteria could be clinically useful to select patients for non-surgical management.

Serum leucine-rich alpha-2-glycoprotein-1 with fucosylated triantennary N-glycan: a novel colorectal cancer marker.

BACKGROUND: Carcinoembryonic antigen (CEA) and carbohydrate antigen (CA)19-9 are used in clinical practice as tumor markers to diagnose or monitor colorectal cancer (CRC) patients, However, their specificities and sensitivities are not ideal, and novel alternatives are needed. In this study, mass spectrometry was used to search for screening markers, focusing on glycan alterations of glycoproteins in the sera of CRC patients. METHODS: Glycopeptides were prepared from serum glycoproteins separated from blood samples of 80 CRC patients and 50 healthy volunteers, and their levels were measured by liquid chromatography time-of flight mass spectrometry (LC-TOF-MS). RESULTS: Leucine-rich alpha-2-glycoprotein-1 with fucosylated triantennary N-glycan (LRG-FTG) was identified as CRC marker after evaluating 30,000 candidate glycopeptide peaks. The average LRG-FTG level in CRC patients (1.25 ± 0.973 U/mL) was much higher than that in healthy volunteers (0.496 ± 0.433 U/mL, P < 10- 10), and its sensitivity and specificity exceeded those of CA19-9. The combination of CEA and LRG-FTG showed a complementary effect and had better sensitivity (84%), specificity (90%), and AUC (0.91 by ROC analysis) than each marker alone or any other previously reported marker. LRG-FTG alone or combined with CEA also corresponded well with patient response to treatment. CONCLUSIONS: We identified LRG-FTG as a new CRC marker, with a sensitivity and specificity exceeding CA19-9. The combination of LRG-FTG and CEA showed much higher sensitivity and specificity than each marker alone. Further validation beyond this initial exploratory cohort is warranted.