The Management of Direct Oral Anticoagulants for Colorectal Endoscopic Submucosal Dissection: A Multicenter Observational Study.

BACKGROUND: There is a lack of reports on the use of direct oral anticoagulants (DOACs) during colorectal endoscopic submucosal dissection (ESD). AIMS: We aimed to assess whether the use of DOACs is associated with a higher incidence of delayed bleeding (DB) after ESD. METHODS: A total of 4175 colorectal neoplasms in 3515 patients were dissected at our hospitals during study period. We included 3909 lesions in the final analysis. The lesions were divided into two groups: the no-AT group (3668 neoplasms) and the DOAC group (241 neoplasms). We also compared the DOAC withdrawal group (154 neoplasms) and the DOAC continuation group (87 neoplasms). RESULTS: Among the 3909 lesions, DB occurred in a total of 90 cases (2.3%). The rate of DB was 2.2% (82/3668), and 3.3% (8/241), respectively. There were no significant differences in the rate of DB between the no-AT group and the DOAC group. In the DOAC group, there were no significant differences in the rate of DB between the withdrawal group (5.2%, 8/154) and the continuation group (0%, 0/87). The multivariable analysis identified the location of the lesion in the rectum (odds ratio [OR], 4.04; 95% confidence interval [CI], 2.614-6.242; p < 0.001) and lesions ≥ 30 mm in diameter (OR, 4.14; 95% CI, 2.349-7.34; p < 0.001) as independent risk factors for DB. CONCLUSIONS: Our findings suggest that DOAC use has no significant important on the rate of DB. Prospective studies are warranted to determine whether treatment with DOACs should be interrupted prior to colorectal ESD.

Long-term Outcomes After Endoscopic Submucosal Dissection for Large Colorectal Epithelial Neoplasms: A Prospective, Multicenter, Cohort Trial From Japan.

BACKGROUND & AIMS: To determine the long-term outcomes after colorectal endoscopic submucosal dissection (ESD), we conducted a large, multicenter, prospective cohort trial with a 5-year observation period. METHODS: Between February 2013 and January 2015, we consecutively enrolled 1740 patients with 1814 colorectal epithelial neoplasms ≥20 mm who underwent ESD. Patients with noncurative resection (non-CR) lesions underwent additional radical surgery, as needed. After the initial treatment, intensive 5-year follow-up with planned multiple colonoscopies was conducted to identify metastatic and/or local recurrences. Primary outcomes were overall survival, disease-specific survival, and intestinal preservation rates. The rates of local recurrence and metachronous invasive cancer were evaluated as the secondary outcomes. RESULTS: The 5-year overall survival, disease-specific survival, and intestinal preservation rates were 93.6%, 99.6%, and 88.6%, respectively. Patients with CR lesions had no metastatic occurrence, and patients with non-CR lesions had 4 metastatic occurrences. Kaplan-Meier curves revealed that overall survival and disease-specific survival rates were significantly higher in patients with CR lesions than in those with non-CR lesions (P > .001 and P = .009, respectively). Local recurrence occurred in only 8 lesions (0.5%), which were successfully resected by subsequent endoscopic treatment. Multiple logistic regression analyses revealed that piecemeal resection (hazard ratio, 8.19; 95% CI, 1.47-45.7; P = .02) and margin-positive resection (hazard ratio, 8.06; 95% CI, 1.76-37.0; P = .007) were significant independent predictors of local recurrence after colorectal ESD. Fifteen metachronous invasive cancers (1.0%) were identified during surveillance colonoscopy, most of which required surgical resection. CONCLUSIONS: A favorable long-term prognosis indicates that ESD can be the standard treatment for large colorectal epithelial neoplasms. CLINICAL TRIAL REGISTRATION NUMBER: UMIN000010136.

Safety and Efficacy of Cold Snare Polypectomy Without Submucosal Injection for Large Sessile Serrated Lesions: A Prospective Study.

BACKGROUND & AIMS: Cold snare polypectomy (CSP) has become the standard resection method for small colorectal polyps (<10 mm). Sessile serrated lesions (SSL) have low prevalence of advanced histology irrespective of size, and thus could be amenable to CSP. In this study, we evaluated the safety and efficacy of CSP for SSLs ≥10 mm. METHODS: Between November 2018 and January 2020, we prospectively enrolled 300 consecutive patients who underwent CSP for 474 SSLs ≥10 mm. To delineate SSL borders, indigo carmine chromoendoscopy and/or image-enhanced endoscopy was conducted. Piecemeal CSP (pCSP) was performed in cases where en-bloc resection was difficult. Biopsy specimens were obtained from the margins of the post-polypectomy defect to confirm complete resection. Surveillance colonoscopy was performed to screen for local recurrence. RESULTS: All lesions were successfully resected using CSP without submucosal injection. The median diameter of the resected lesions was 14 mm, and pCSP was used to resect 106 (22%) lesions. Post-polypectomy biopsies revealed residual serrated tissue in only one case (0.2%). Adverse events included immediate bleeding in 8 (3%) patients; no delayed bleeding events occurred, irrespective of the use of antithrombotic drugs. During a 7-month median follow-up period, surveillance colonoscopies were performed for 384 lesions (81%), and no local recurrences were detected. CONCLUSIONS: CSP without submucosal injection is a safe and effective treatment for SSLs ≥10 mm. UMIN Clinical Trials, Number: UMIN000034763.

The feasibility of endoscopic submucosal dissection for colorectal lesions larger than 10 cm.

BACKGROUND: Although endoscopic submucosal dissection (ESD) enables en bloc removal of colorectal neoplasms, its effectiveness for larger lesions (≥ 10 cm in diameter) is undetermined. We aimed to investigate the feasibility and safety of ESD for colorectal lesions ≥ 10 cm wide. METHODS: This retrospective study included 3591 consecutive colorectal lesions managed with ESD from June 2012 through December 2020. Clinicopathological characteristics and treatment outcomes were compared between lesions ≥ 10 cm wide and lesions 5-10 cm wide. RESULTS: There were 50 patients in the ≥ 10 cm group and 270 patients in the 5-10 cm group. Among patients in the ≥ 10 cm group, lesions were most often in the rectum (50.0%), and the laterally spreading tumor-granular nodular mixed type (LST-G-M) was most prevalent (41/50, 82%). Although patients in the ≥ 10 cm group a longer mean ESD procedure time (186.0 vs. 94.4 min, p < 0.001), the dissection speed was significantly higher in this group (0.50 vs. 0.41 cm2/min, p = 0.003). The en bloc and curative resection rates were comparable between the ≥ 10 cm and 5-10 cm groups (100% vs. 99.6% and 86.0% vs. 88.5%, respectively). Although the stenosis rate was higher in the ≥ 10 cm group (4% vs. 0%), the delayed bleeding and perforation rates were similar between the two groups. CONCLUSIONS: ESD for colorectal lesions ≥ 10 cm wide is feasible and curative, even though it is associated with higher technical difficulty and longer procedure times compared with ESD for smaller lesions (Number: UMIN 000044313).

Evaluation of colorectal endoscopic submucosal dissection using a multifunctional snare: a prospective clinical feasibility study (with videos).

BACKGROUND AND AIMS: The number of colorectal endoscopic submucosal dissections (ESDs) for early colorectal cancer is expected to increase in the future; therefore, cost reduction is a clinically important issue. The SOUTEN snare (Kaneka Medics, Tokyo, Japan) is a novel multifunctional snare developed for hybrid ESD at a low price. If ESD can be performed safely using the SOUTEN snare, the same therapeutic effect can be obtained as with conventional ESD at a lower cost. The aim of this prospective, pilot, clinical feasibility study was to evaluate the safety and efficacy of ESD using the SOUTEN snare (SOUTEN-ESD). METHODS: From October 2018 to January 2019, 119 consecutive patients (121 ESD procedures, 137 colorectal neoplasms) were prospectively enrolled and treated by SOUTEN-ESD at NTT Medical Center Tokyo and Omori Red Cross Hospital. The outcomes of SOUTEN-ESD were evaluated. RESULTS: Among 137 neoplasms, SOUTEN-ESD was completed in all cases. No cases required conversion to hybrid ESD or to a dedicated ESD device. The mean procedure time was 26.1 ± 14.3 minutes. Both the en-bloc resection rate and R0 resection rate were 100%. The rate of perforation was 0%, the rate of delayed bleeding was 2.2%, and the rate of post-ESD coagulation syndrome was 2.9%. CONCLUSIONS: SOUTEN-ESD was safe and had good outcomes. Although further studies are required to examine indications for SOUTEN-ESD and confirm the results of this study, effective ESD with this novel knife is feasible. The SOUTEN snare is a realistic option for colorectal ESD. (Clinical trial registration number: UMIN 000034299.).

A new classification for the diagnosis of superficial non-ampullary duodenal epithelial tumors using endocytoscopy: A prospective study.

BACKGROUND AND AIM: Although the frequency of endoscopic diagnosis of superficial non-ampullary duodenal epithelial tumors (SNADETs) has been increasing in recent years, no criteria for the endoscopic diagnosis of these tumors have been established yet. The aim of this study was to assess the usefulness of endocytoscopy for diagnosis SNADETs and to establish new criteria. METHODS: This prospective study was conducted at the NTT Medical Center Tokyo from May 2019 to July 2020, and a total of 100 consecutive SNADETs were enrolled. All the endocytoscopic images of the lesions and surrounding normal mucosa were classified into three groups according to the degree of structural atypia and the nuclear morphology and size. The endocytoscopic diagnoses using endocytoscopic classification was compared with the final histopathological diagnoses. RESULTS: Data of 93 patients with 98 lesions were included in the analysis. The preoperative diagnosis by endocytoscopy coincided with the final histopathological diagnosis in 85 (86.7%) of 98 SNADETs. In addition, the sensitivity and specificity for VCL 4/5 were 87.7% and 85.4%, respectively. In contrast, the accuracy, sensitivity, and specificity of preoperative diagnosis by biopsy were 64.3%, 50.9%, and 82.9%, respectively. Preoperative diagnosis by endocytoscopy showed significantly superior accuracy and sensitivity as compared with preoperative biopsy diagnosis (P < 0.001, respectively). CONCLUSIONS: This new classification (endocytoscopic classification) allows prediction of the tumor histopathology in real time, during endocytoscopy without biopsy, and is expected to be of help in determining the appropriate therapeutic strategies for individual cases of SNADETs. (Clinical trial registration number: UMIN000038643.).

Endoscopic submucosal dissection for colorectal neoplasms in proximity or extending to a diverticulum.

BACKGROUND AND AIMS: At specialized facilities, endoscopic submucosal dissection (ESD) has currently been performed even for difficult cases such as tumors extending to a diverticulum that previously required surgery. This study aims to classify the type of lesion according to the degree of infiltration to a diverticulum and assessed the safety and efficacy of ESD for each type of lesion. METHODS: We retrospectively reviewed ESD for lesions at NTT Medical Center Tokyo between January 2014 and April 2019. Lesions were classified as follows: Type 1: lesions in contact with or within 3 mm of the edge of a diverticulum; Type 2: lesions that partially infiltrated into a diverticulum; and Type 3: lesions that infiltrated into and completely covered the diverticulum. Furthermore, ESD strategies were divided into A and B, which indicates that a lesion was resected separately from the diverticulum and along the entire diverticulum, respectively. The clinicopathological characteristics and clinical outcomes were analyzed according to the strategy. RESULTS: A total of 47 lesions satisfied inclusion criteria (19 Type 1, 12 Type 2, and 16 Type 3 lesions). 19 Type 1 and 8 Type 2 lesions were resected using Strategy A, while 4 Type 2 and 16 Type 3 lesions were resected using Strategy B. En bloc resection was achieved in all cases. In Strategy A, the R0 resection rate was 96.3% and the curative resection rate was 88.9%. On the contrary, in Strategy B, the R0 resection rate was 95.0% and the curative resection rate was 90.0%. In Strategy B, one of the patients developed post-operative bleeding that required endoscopic hemostasis; another patient developed delayed perforation that required emergency surgery. CONCLUSIONS: ESD for colorectal neoplasms in proximity or extending to a diverticulum is challenging, but this procedure can be a safe and effective therapeutic option.

Simple scoring system for the diagnosis of superficial non-ampullary duodenal epithelial tumors.

BACKGROUND AND AIMS: Differentiating superficial non-ampullary duodenal epithelial tumors (SNADETs) that harbor malignant potential is important. We developed a simple scoring system and investigated whether it enables the differentiation of low-grade adenoma and high-grade adenoma/adenocarcinoma. PATIENTS AND METHODS: We retrospectively enrolled 197 consecutive patients with 207 SNADETs who underwent endoscopic resection at NTT Medical Center Tokyo between March 2016 and May 2019. Endoscopic findings were compared between Vienna Classification (VCL) C3 and C4/5 lesions. A multivariate logistic regression analysis was performed to develop a scoring system to identify VCL C4/5 lesions. The efficacy of our scoring system was elucidated among five novice and five expert endoscopists. RESULTS: Of 207 SNADETs, 66 and 141 lesions were pathologically diagnosed as VCL C3 and C4/5. A multivariate logistic regression analysis identified a tumor diameter of 10-19 mm (OR, 3.81; 95% CI, 1.02-14.2; P = 0.04), a tumor diameter ≥20 mm (OR, 95.2; 95% CI, 10.4-871.0; P < 0.001), a red color (OR, 14.5; 95% CI, 3.55-59.6; P < 0.001), the presence of irregular surface pattern (OR, 12.4; 95% CI, 3.00-51.4; P < 0.001), and the presence of irregular vessel pattern (OR, 13.7; 95% CI, 4.03-46.6; P < 0.001) as independent significant predictors of VCL C4/5. Considering these results, we developed a scoring system. Using an appropriate cutoff value, the diagnostic accuracy, sensitivity and specificity were calculated as 92%, 95% and 93%. The average diagnostic accuracy did not differ between novice and expert endoscopists (86% vs 87%, P = 0.76). CONCLUSIONS: Our scoring system was useful for differentiating VCL C3 and C4/5 lesions. UMIN Clinical Trials (No. 000039063).

Risk factors of delayed bleeding after endoscopic resection of superficial non-ampullary duodenal epithelial tumors and prevention by over-the-scope and conventional clipping.

OBJECTIVES: This study was aimed to reveal risk factors for delayed bleeding after endoscopic resection (ER) of superficial non-ampullary duodenal epithelial tumors (SNADETs) and at exploring measures to prevent this complication. METHODS: A total of 235 consecutive patients with 249 SNADETs who had undergone ER were enrolled in this study. They were divided into two groups: OTSC group, consisting of the initial 114 cases in which the defects were closed only using OTSCs; and OTSC-c group, consisting of the later 135 cases in which conventional clips were additionally used to cover the inverted submucosa after post-procedure defect closure using OTSCs. The therapeutic outcomes were then compared between the OTSC and OTSC-c groups. RESULTS: All lesions were successfully resected en-bloc, and the R0 resection rate was 92.4%. The complete defect closure rate was 90.0% and no delayed perforation occurred when successful defect closure was achieved. The rate of delayed bleeding was significantly higher in the OTSC group than in OTSC-c group (11.4% vs. 1.5%, P = 0.001). Multivariate logistic regression analyses revealed that tumor location distal to the ampulla (OR 10.0; 95% CI 1.24-81.0, P = 0.03) and use of a DOAC (OR 8.83; 95% CI 1.13-68.7, P = 0.04) were significant independent predictors of delayed bleeding. Propensity score-matching analysis revealed that additional use of conventional clips was associated with a significantly reduced risk of delayed bleeding (P = 0.003). CONCLUSIONS: Additional use of conventional clips after prophylactic defect closure using OTSCs appears to be useful to reduce the risk of delayed bleeding after ER of SNADETs. UMIN Clinical Trials (No. 000035478).

Clinical characteristic of esophageal cancer without lugol-voiding lesions in the background esophagus.

Lugol chromoendoscopy is useful for the detection of early esophageal squamous cell cancer (ESCC). Multiple lugol-voiding lesions (LVLs) on lugol chromoendoscopy are associated with a very high risk of multiple cancers arising in the esophagus. Due to the widespread use of narrow band image technology in many institutions, esophageal cancer without LVLs in the background esophagus is sometimes detected. This retrospective study aims to clarify the clinical characteristic of esophageal cancer without LVLs in the background esophagus. A total of 191 consecutive patients with 204 ESCCs had undergone endoscopic submucosal dissection (ESD) from 2011 and 2014. Amongst these lesions, the number of LVLs in the background esophagus per endoscopic view was counted excluding main lesion, and the grading was divided into no LVLs ESCC (nL-ESCC) group and LVLs ESCC (L-ESCC) group. This study evaluated the clinical characteristics and the cumulative incidence of metachronous ESCC after ESD in both groups. Thirty-six patients with 36 lesions and 155 patients with 168 lesions were separated into the nL-ESCC group and L-ESCC group, respectively. On multivariate analysis, the nL-ESCC group was found to be more common in females, who were non-drinkers, or with erosive esophagitis. During follow-up periods, the cumulative incidence of metachronous ESCC at 3-years was 14.4% and 0.00% in the L-ESCC and nL-ESCC groups, respectively (P < 0.01). Our study showed that esophageal cancer without LVLs in the background esophagus was mostly occurred in females, who were non-drinkers, or with erosive esophagitis, which are uncommon features of ESCC.

Efficacy of Upper Gastrointestinal Endoscopic Examination to Identify Patients with Obstructive Sleep Apnea Syndrome: A Retrospective Cross-Sectional Study.

BACKGROUND/AIMS: Despite the high prevalence of obstructive sleep apnea syndrome (OSAS), most individuals are unaware of its diagnosis. We assessed whether an upper gastrointestinal (GI) endoscopy can accurately predict the incidence of OSAS. METHODS: After endoscopic evaluation of laryngo-pharyngeal collapse, a total of 154 subjects with laryngo-pharyngeal collapse and 52 control subjects underwent polysomnography. Based on the modified Fujita Classification, upper airway obstruction was classified into 3 different types: oropharyngeal, supraglottic and combined type, and associations between upper airway obstruction and OSAS were evaluated. RESULTS: Of 154 subjects with laryngo-pharyngeal collapse, 108 (70.1%) were diagnosed as OSAS, while only 4 (7.7%) control subjects were diagnosed as OSAS (p < 0.001). The sensitivity and specificity of endoscopic diagnosis were 96.4 and 51.1%, respectively. Oropharyngeal involvement was frequently found in 90.2% of the subjects (139/154). The severity of upper airway obstruction was significantly correlated with the apnea-hypopnea index score (r = 0.55, p < 0.001). A multivariate logistic regression analysis revealed that a male sex (OR 5.20; 95% CI 2.65-10.2, p < 0.001), body mass index ≥25 kg/m2 (OR 4.98; 95% CI 2.23-11.2, p = 0.02) and severe obstruction (OR 7.79; 95% CI 3.34-18.2, p < 0.001) were significant independent predictors of severe OSAS. CONCLUSION: A conventional upper GI endoscopic examination might be useful as a diagnostic modality for OSAS.

Clinical Outcomes of Patients with Small Rectal Neuroendocrine Tumors Treated Using Endoscopic Submucosal Resection with a Ligation Device.

BACKGROUND/AIMS: The therapeutic strategies for small rectal neuroendocrine tumors (NETs) have not been standardized. We examined the efficacy and safety of endoscopic submucosal resection with a ligation device (ESMR-L) and the long-term outcomes after endoscopic treatment. METHODS: A total of 181 patients with rectal NETs <10 mm who were treated between May 2002 and May 2017 were retrospectively enrolled. All the lesions had been resected using ESMR-L, and the follow-up strategies were determined according to the pathological examinations. The long-term outcomes after a 53-month follow-up period were also evaluated. RESULTS: R0 resection was achieved in 180 cases (99.4%). Lymphovascular invasion was confirmed in 67 cases (37.0%), while a curative resection was achieved in 114 cases (63.0%). One perforation (0.6%) and 11 cases with delayed bleeding (6.1%) were observed. A multivariate logistic regression analysis revealed that a tumor size > 5 mm (OR 2.06; 95% CI 1.04-4.08, p = 0.04) was a significant independent predictor of the presence of lymphovascular invasion. Of the 67 patients with non-curative resections, 11 patients underwent additional surgery; lymph node metastasis was confirmed in 2 cases (18.2%). No local or distant metastases were observed during the follow-up period in 77 patients with a curative resection, 9 patients who received additional surgery, and 50 patients with non-curative resections. CONCLUSION: ESMR-L is an easy, safe and effective treatment for rectal NETs <10 mm in diameter, and the prognosis of patients seems to be good, despite a relatively high rate of lymphovascular invasion.

Efficacy of an over-the-scope clip for preventing adverse events after duodenal endoscopic submucosal dissection: a prospective interventional study.

BACKGROUND: Duodenal endoscopic submucosal dissection (ESD) remains technically challenging, with a high risk of severe adverse events. Because exposure of the duodenal post-ESD mucosal defect to pancreatic juice and bile acid reportedly induces delayed perforation and bleeding, we examined whether defect closure using an over-the-scope clip (OTSC) system was useful for preventing postoperative adverse events. METHODS: From April 2016 to February 2017, a total of 50 consecutive patients with superficial non-ampullary duodenal epithelial tumors (SNADETs) larger than 10 mm, with no more than semi-circumferential spread, were prospectively enrolled in this study. All of the lesions were treated by experienced ESD operators and the post-ESD mucosal defect was closed using OTSCs. RESULTS: All of the SNADETs were completely removed by ESD, with an R0 resection rate of 88.0 %. The mean procedure and closure times were 67.3 ±â€Š58.8 minutes and 9.8 ±â€Š7.2 minutes, respectively. Although complete defect closure was achieved in 94.0 % of the patients (47/50), two patients required surgical conversion. Delayed perforation occurred in only one patient (2.1 %), who did not have successful closure of the defect, as misplacement of the OTSC exposed the muscle layer. Meanwhile, delayed bleeding occurred in three patients (6.3 %); however, the bleeding was easily controlled using endoscopic coagulation. The mean duration of postoperative hospitalization was 5.5 ±â€Š7.2 days. CONCLUSIONS: Prophylactic defect closure using OTSCs may be effective in reducing severe adverse events after duodenal ESD.

Surveillance of patients with long-segment Barrett's esophagus: A multicenter prospective cohort study in Japan.

BACKGROUND AND AIM: The incidence of esophageal adenocarcinoma (EAC) in cases with long-segment Barrett's esophagus (BE) has not been investigated in Japan. The aim of this study is to investigate the incidence of EAC in Japanese cases with long-segment BE prospectively. METHODS: This is a multicenter prospective cohort study investigating the incidence rate of EAC in patients with BE with a length of at least 3 cm. Study subjects received index esophagogastroduodenoscopy at the time of enrollment, and they were instructed to undergo yearly follow-up esophagogastroduodenoscopy. Patients in whom EAC was diagnosed in the endoscopic examinations underwent subsequent treatment, and their prognosis was observed. RESULTS: Of 215 enrolled patients, six (2.8%) were initially diagnosed with EAC at the enrollment. Among the remaining 209 patients, 132 received at least one follow-up esophagogastroduodenoscopy. In this follow-up, three EACs developed in 251 observed patient-years (incidence rate: 1.2% per year). Most of the EACs detected at the initial endoscopic examination (5/6, 83%) were already at advanced stages. Meanwhile, all the three lesions detected in the follow-up esophagogastroduodenoscopies were identified as early cancers and subjected to curative resection. CONCLUSIONS: The incidence rate of EAC in Japanese cases with long-segment BE was calculated to be 1.2% in a year.

Endoscopic submucosal dissection for laterally spreading tumors involving the appendiceal orifice.

BACKGROUND: Since the endoscopic resection of laterally spreading tumors (LSTs) involving the appendiceal orifice remains technically difficult, such lesions are usually treated by surgical resection. However, with recent advances in endoscopic devices, endoscopic submucosal dissection (ESD) has become feasible and may be safely performed even for lesions involving the appendiceal orifice. Therefore, in order to assess the validity of endoscopic treatment for such lesions, we retrospectively evaluated the safety and efficacy of ESD. METHODS: A total of 30 patients with LSTs extending to within 10 mm of the appendiceal orifice (Group AO) and 122 patients with cecal LSTs located away from the appendiceal orifice (Group C) who were treated between December 2011 and September 2015 were retrospectively enrolled in the present study. The indications for ESD were determined by the preoperative endoscopic diagnosis made on the basis of Kudo's pit pattern classification. Based on these preoperative endoscopic diagnoses, 8 of the 30 enrolled patients underwent surgical resection as the initial treatment, because the tumor showed deep invasion beyond the orifice and/or a VN pit pattern was visible. The treatment outcomes (en bloc R0 resection rates, tumor size, procedure time, and complication rates) were compared between the two groups. RESULTS: The sensitivity and specificity for the cancer diagnosis were 81.8 and 94.7%, respectively. There was no significant difference in the en bloc R0 resection rate between Group AO and Group C (90.9 vs. 95.9%, P = 0.23). Furthermore, there were also no differences in the mean tumor size (30.0 ± 20.8 vs. 34.9 ± 14.5 mm, P = 0.17) or mean OR time (55.0 ± 39.2 vs. 58.9 ± 48.2 min P = 0.72) between the two groups. One case from Group AO (4.5%) was complicated by a perforation, which was successfully managed endoscopically. CONCLUSIONS: Although proficiency in endoscopic techniques is required, our results indicate that LSTs involving the appendiceal orifice can be successfully treated by ESD.

Metformin for chemoprevention of metachronous colorectal adenoma or polyps in post-polypectomy patients without diabetes: a multicentre double-blind, placebo-controlled, randomised phase 3 trial.

BACKGROUND: The prevalence of, and mortality from, colorectal cancer is increasing worldwide, and new strategies for prevention are needed to reduce the burden of this disease. The oral diabetes medicine metformin might have chemopreventive effects against cancer, including colorectal cancer. However, no clinical trial data exist for the use of metformin for colorectal cancer chemoprevention. Therefore, we devised a 1-year clinical trial to assess the safety and chemopreventive effects of metformin on sporadic colorectal cancer (assessed by adenoma and polyp recurrence) in patients with a high risk of adenoma recurrence. METHODS: This trial was a multicentre, double-blind, placebo-controlled, randomised phase 3 trial. Non-diabetic adult patients who had previously had single or multiple colorectal adenomas or polyps resected by endoscopy were enrolled into the study from five hospitals in Japan. Eligible patients were randomly assigned (1:1) to receive oral metformin (250 mg daily) or identical placebo tablets by a stratified computer-based randomisation method, with stratification by institute, age, sex, and body-mass index. All patients, endoscopists, doctors, and investigators were masked to drug allocation until the end of the trial. After 1 year of administration of metformin or placebo, colonoscopies were done to assess the co-primary endpoints: the number and prevalence of adenomas or polyps. Our analysis included all participants who underwent random allocation, according to the intention-to-treat principle. This trial is registered with University Hospital Medical Information Network (UMIN), number UMIN000006254. FINDINGS: Between Sept 1, 2011, and Dec 30, 2014, 498 patients who had had single or multiple colorectal adenomas resected by endoscopy were enrolled into the study. After exclusions for ineligibility, 151 patients underwent randomisation: 79 were assigned to the metformin group and 72 to the placebo group. 71 patients in the metformin group and 62 in the placebo group underwent 1-year follow-up colonoscopy. The prevalence of total polyps (hyperplastic polyps plus adenomas) and of adenomas in the metformin group was significantly lower than that in the placebo group (total polyps: metformin group 27 [38·0%; 95% CI 26·7-49·3] of 71 patients, placebo group 35 [56·5%; 95% CI 44·1-68·8] of 62; p=0·034, risk ratio [RR] 0·67 [95% CI 0·47-0·97]; adenomas: metformin group 22 [30·6%; 95% CI 19·9-41·2] of 71 patients, placebo group 32 [51·6%; 95% CI 39·2-64·1] of 62; p=0·016, RR 0·60 [95% CI 0·39-0·92]). The median number of polyps was zero (IQR 0-1) in the metformin group and one (0-1) in the placebo group (p=0·041). The median number of adenomas was zero (0-1) in the metformin group and zero (0-1) in the placebo group (p=0·037). 15 (11%) of patients had adverse events, all of which were grade 1. We recorded no serious adverse events during the 1-year trial. INTERPRETATION: The administration of low-dose metformin for 1 year to patients without diabetes was safe. Low-dose metformin reduced the prevalence and number of metachronous adenomas or polyps after polypectomy. Metformin has a potential role in the chemoprevention of colorectal cancer. However, further large, long-term trials are needed to provide definitive conclusions. FUNDING: Ministry of Health, Labour and Welfare, Japan.

Genetic and epigenetic aberrations occurring in colorectal tumors associated with serrated pathway.

To clarify molecular alterations in serrated pathway of colorectal cancer (CRC), we performed epigenetic and genetic analyses in sessile serrated adenoma/polyps (SSA/P), traditional serrated adenomas (TSAs) and high-methylation CRC. The methylation levels of six Group-1 and 14 Group-2 markers, established in our previous studies, were analyzed quantitatively using pyrosequencing. Subsequently, we performed targeted exon sequencing analyses of 126 candidate driver genes and examined molecular alterations that are associated with cancer development. SSA/P showed high methylation levels of both Group-1 and Group-2 markers, frequent BRAF mutation and occurrence in proximal colon, which were features of high-methylation CRC. But TSA showed low-methylation levels of Group-1 markers, less frequent BRAF mutation and occurrence at distal colon. SSA/P, but not TSA, is thus considered to be precursor of high-methylation CRC. High-methylation CRC had even higher methylation levels of some genes, e.g., MLH1, than SSA/P, and significant frequency of somatic mutations in nonsynonymous mutations (p < 0.0001) and insertion/deletions (p = 0.002). MLH1-methylated SSA/P showed lower methylation level of MLH1 compared with high-methylation CRC, and rarely accompanied silencing of MLH1 expression. The mutation frequencies were not different between MLH1-methylated and MLH1-unmethylated SSA/P, suggesting that MLH1 methylation might be insufficient in SSA/P to acquire a hypermutation phenotype. Mutations of mismatch repair genes, e.g., MSH3 and MSH6, and genes in PI3K, WNT, TGF-ß and BMP signaling (but not in TP53 signaling) were significantly involved in high-methylation CRC compared with adenoma, suggesting importance of abrogation of these genes in serrated pathway.

TP53 mutation at early stage of colorectal cancer progression from two types of laterally spreading tumors.

Although most sporadic colorectal cancers (CRC) are thought to develop from protruded adenomas through the adenoma-carcinoma sequence, some CRC develop through flat lesions, so-called laterally spreading tumors (LST). We previously analyzed epigenetic aberrations in LST and found that LST are clearly classified into two molecular subtypes: intermediate-methylation with KRAS mutation and low-methylation with absence of oncogene mutation. Intermediate-methylation LST were mostly granular type LST (LST-G) and low-methylation LST were mostly non-granular LST (LST-NG). In the present study, we conducted a targeted exon sequencing study including 38 candidate CRC driver genes to gain insight into how these genes modulate the development of LST. We identified a mean of 11.5 suspected nonpolymorphic variants per sample, including indels and non-synonymous mutations, although there was no significant difference in the frequency of total mutations between LST-G and LST-NG. Genes associated with RTK/RAS signaling pathway were mutated more frequently in LST-G than LST-NG (P = 0.004), especially KRAS mutation occurring at 70% (30/43) of LST-G but 26% (13/50) of LST-NG (P < 0.0001). Both LST showed high frequency of APC mutation, even at adenoma stage, suggesting its involvement in the initiation stage of LST, as it is involved at early stage of colorectal carcinogenesis via adenoma-carcinoma sequence. TP53 mutation was never observed in adenomas, but was specifically detected in cancer samples. TP53 mutation occurred during development of intramucosal cancer in LST-NG, but during development of cancer with submucosal invasion in LST-G. It is suggested that TP53 mutation occurs in the early stages of cancer development from adenoma in both LST-G and LST-NG, but is involved at an earlier stage in LST-NG.