Vertical Margin Research Articles

The impact of additional treatment after endoscopic submucosal dissection for esophageal squamous cell carcinoma in real-world clinical practice.

305 Background: Endoscopic submucosal dissection (ESD) is the standard therapy for the T1a- EP/LPM esophageal squamous cell carcinoma (ESCC), although it is difficult to diagnose the invasion depth accurately before ESD. The incidence of lymph node metastases in ESCC involving the muscularis mucosae (pT1a-MM) and the submucosa (pT1b-SM) is reported to range from approximately 10% to 30%. For the patients with MM, SM or involving LVI or positive vertical margin after ESD, additional treatment (AT) is recommended to prevent local recurrence. However, the AT is not always performed to the frail or elderly patients. The aim of this study is to investigate the outcome of AT and non-AT (NAT) after ESD for ESCC in the real-world clinical practice. Methods: We retrospectively reviewed the ESCC patients who were pathologically confirmed T1a-MM or T1b-SM (UICC-TNM7th) after ESD at Osaka medical college hospital between 2004 and 2016. Results: Among 224 patients who received ESD, 52 patients were pT1a-MM (n = 36; 69.2%) or pT1b-SM (n = 16; 30.8%).Twelve of 52 patients (23%) received AT and forty patients (77%) received NAT. Six patients (AT group: 2 patients, NAT group: 4 patients) had local lymph node recurrence. Five of them underwent salvage therapy. Median follow up time were 54.3 months (range: 48.4-62.4). The 3-, 5-year RFS rate and the 3-, 5-year OS rate were 83.8%[95%CI: 68.2- 92.6], 73.4% [95%CI: 56.0- 85.7] and 94.7% [95%CI: 81.3- 98.6], 91.7% [95%CI: 77.1- 97.3] in all patients, respectively. The 5-year RFS and OS rate were 77.8%, 90.0% in the AT group and 71.6, 92.2% in the NAT group. Conclusions: Although the AT tended to prevent local recurrence, the OS was comparable with NAT because of salvage therapy. The active surveillance is recommended for T1a-MM or T1b-SM ESCC.

A new procedure combining local resection with endoscopic submucosal dissection for low rectal tumor: a four-case series.

Rectal tumors are traditionally resected by proctectomy to ensure the achievement of negative margins, an approach associated with an adverse impact on subsequent quality of life due to sequelae such as permanent stoma and urinary and sexual dysfunction. Many studies have now demonstrated that recurrence after local excision of early rectal tumors is significantly higher than would typically be expected. We have developed a new procedure, described herein, that combines local resection with endoscopic submucosal dissection for low rectal tumor. We report four consecutive cases (three submucosal tumors and one tumor with clinical deep submucosal invasion) treated at Hiroshima City Asa Citizens Hospital between January 2009 and March 2018. The mean duration of the procedure was 137 minutes. The en bloc resection and histologically complete resection rates were 100 %. Delayed bleeding and perforation rates were 0 %. Postoperative complications were fever and anal pain (one case each). All patients recovered with conservative therapy. No recurrence was found in any of the four patients during a follow-up period of 56 months. Our combined endoscopic and surgical procedure for low rectal tumors enabled definite negative vertical margins, reduced tumor volume, allowed for accurate pathological diagnosis, preserved rectal function, and aided the decision on additional therapy.

Short- and long-term outcomes of endoscopic submucosal dissection for non-ampullary duodenal neuroendocrine tumors.

BackgroundEndoscopic resection is recommended for non-ampullary duodenal neuroendocrine tumors (NAD-NETs) ≤10 mm in diameter and confined to the submucosal layer, without lymph node or distant metastasis. However, the efficacy and safety of endoscopic submucosal dissection (ESD) for NAD-NET remains unclear. The aim of this study was to assess the short-term efficacy and safety and the long-term outcomes of ESD for NAD-NET.MethodsEight patients with 8 NAD-NETs who underwent ESD between 2015 and 2018 were included. The indications for ESD were: i) tumor ≤10 mm in diameter; ii) NET G1; iii) confined to the submucosal layer; and iv) without lymph node or distant metastasis. We retrospectively assessed the short- and long-term outcomes and safety.ResultsThe median patient age was 69 (48-76) years. All tumors were located in the duodenal bulb and showed 0-Is morphology. The median size was 6.4 (3-9.3) mm. The rates of en bloc resection, histologically free horizontal and vertical margins, and curative resection were 100%, 88%, and 88%, respectively. Intraoperative and postoperative perforation each occurred in 13% of patients, all of whom were treated conservatively and avoided emergent surgery. Delayed bleeding was not observed. No local, lymph node or distant recurrence was observed during a median follow-up period of 34 (18.5-62.5) months.ConclusionsThe rates of en bloc and curative resection, and histologically free margins were sufficiently high. Although intraoperative and postoperative perforations occurred, emergency surgery was not needed. The results show that ESD is an efficacious and safe treatment for NAD-NET.

Comparative Analysis of Marginal Accuracy of Complete Crowns Fabricated by Using Ringless and Metal Ring Investment Systems: An In Vitro Study

To compare the vertical margin accuracy of lost wax castings produced by the conventional casting technique with all metal (WIRONIUM®) and PFM alloy (WIRON®99) using a metal ring and ringless system. A brass die assembly was used to fabricate standardized wax pattern crowns. A total of 100 wax patterns were made with both ringless and metal ring investment systems. Wax patterns were readapted and refined on the master die and divided into two groups, namely, group I and group II with 50 wax patterns in each group. Group I (ringless system) and group II (metal ring system) were further divided into subgroups having a sample size of 25 in each group. Each coping was invested and cast individually. The marginal discrepancy between the metal die and the castings were measured by a stereomicroscope and AutoCAD software 2013. Measurement was made on the facial area of the metal die. The resultant casts obtained from different casting systems show statistically significant difference found between the marginal discrepancies using metal ring and ringless castings system, and statistically nonsignificant difference was found between the marginal discrepancies using all metal alloy (WIRONIUM®) and PFM alloy (WIRON®99) within the same group. The marginal discrepancy for castings made with ringless casting system was less when compared to metal ring casting system, and there was no difference in marginal discrepancy when compared to all metal alloy (WIRONIUM®) and PFM alloy (WIRON®99) within the same group. Marginal fit is influenced by several factors including type of crown, tooth preparation geometry, dimensional accuracy of impression materials, factors related to dental casting, type of cement, luting pressure, duration of cementation, and use of occlusal vents or die spacers.

Predictors of lymph node metastasis and residual tumor in early gastric cancer patients after noncurative endoscopic resection: a systematic review and meta-analysis.

Background:It is challenging to identify the prevalence of lymph node metastasis (LNM) and residual tumor in patients with early gastric cancer (EGC) who underwent noncurative endoscopic resection (ER). This present meta-analysis was aimed to establish imperative potential predictive factors in order to select the optimal treatment method.Methods:A systematic literature search of PubMed, Embase, and Cochrane Library databases was performed through 1 February 2019 to identify relevant studies, which investigated risk factors for LNM and residual tumor in patients with EGC who underwent noncurative ER. Eligible data were systematically reviewed through a meta-analysis.Results:Overall, 12 studies investigating the risk factor of LNM were included, totaling 3015 patients, 7 of which also involved cancer residues. After the present meta-analysis, six predictors, including tumor size >30 mm, tumor invasion depth (⩾500 μm from the muscularis mucosae), macroscopic appearance, undifferentiated histopathological type, positive vertical margin, and presence of lymphovascular invasion (including lymphatic invasion and vascular invasion) were significantly associated with LNM, whereas tumor size >30 mm, positive horizontal margin, and positive vertical margin were identified as significant predictors for the risk of residual tumor. No evidence of publication bias was observed.Conclusions:Six and three variables were established as significant risk factors for LNM and residual tumor in patients with EGC who underwent noncurative ER, respectively. Patients with EGC who present these risk factors after noncurative ER are strongly suggested to receive additional surgery, while others might be suitable for strict follow-up. This might shed some new light on the selection of follow-up treatment for noncurative ER.

Clinical outcomes of early gastric cancer with non-curative resection after pathological evaluation based on the expanded criteria.

Additional surgical resection should be considered for the patients with pathological findings beyond the expanded criteria with the risk for LN metastasis. However, close observation without additional surgery may be applied because of various reasons. We aimed to determine the clinical outcomes of early gastric cancer beyond the expanded criteria after endoscopic resection according to the pathological extent. A total of 288 patients with 289 lesions beyond the expanded criteria of endoscopic submucosal dissection for early gastric cancer were analyzed between 2005 and 2016, and classified into two groups according to additional treatment: observation (n = 175 patients, 175 lesions) and surgery (n = 113 patients, 114 lesions). The depth of tumor invasion was greater and the tumor-positive vertical margin and lymphatic and venous invasion were more common in the surgery group than in the observation group (P<0.001). Residual, synchronous, and metachronous tumors were more common in the observation group; however, the occurrence of regional lymph node and distant metastasis did not differ between the groups. Overall survival and 5-year disease-specific survival did not differ between the groups (observation vs surgery, 88.6 vs 93.8%; P = 0.259, 98.2 vs 100%; P = 0.484, respectively), but the 5-year disease-free survival was lower in the observation group (73.5 vs 97.9%; P<0.001). On multivariate analysis, tumor-positive lateral margin was a risk factor for residual tumor and lymphatic and venous invasion were risk factors for regional lymph node metastasis. In conclusion, the clinical course of beyond the expanded criteria of endoscopic submucosal dissection for early gastric cancer showed good prognosis over 98% in 5-year disease specific survival. If additional surgery cannot be performed, a close follow-up with endoscopy and abdominal computed tomography can be considered as an alternative for carefully selected patients without lymphatic and vascular invasion.

Marginal Gap Distance and Fracture Resistance of Lithium Disilicate and Zirconia-Reinforced Lithium Disilicate All-Ceramic Crowns Constructed With Two Different Processing TechniquesWith Two Different Processing Techniques

Statement of problem: The microstructure and processing methods used to produce any dental restoration might affect the final mechanical outcomes as well as the clinical success. Objectives: The purpose of this study was to evaluate the fracture resistance of lithium disilicate and zirconia reinforced lithium disilicate ceramic crowns constructed using two processing techniques after fatigue loading namely, CAD/CAM technique and pressing technique. The marginal integrity of the crowns was examined before and after fatigue loading. Methods: A total number of thirty-two freshly extracted maxillary first molars were collected. The teeth were chosen to be of similar bucco-lingual and mesiodistal dimensions. The teeth were mounted vertically into epoxy resin templates. Full coverage all-ceramic preparation was performed for all samples using a standardized technique. The prepared teeth were randomly divided into four equal groups (n=8) according to the all-ceramic materials and technique used for crown fabrication as follows: Group I: IPS e-max CAD(EC): eight prepared teeth were restored with machinable lithium disilicate glass ceramics. Group II: Celtra Duo(CD): eight prepared teeth were restored with machinable zirconia-reinforced lithium disilicate glass ceramics. Group III: IPS e-max Press (EP): eight prepared teeth were restored with pressable lithium disilicate glass ceramics. Group IV: Celtra Press (CP): eight prepared teeth were restored with pressable zirconia-reinforced lithium disilicate glass ceramics. The crowns were cemented using self-adhesive resin cement (Rely X Unicem). Vertical margin gap distance of all the crowns was measured using a stereomicroscope. Following vertical marginal gap distance measurements, the samples were subjected to fatigue cyclic loading for 60000 cycles which is equivalent to six months clinical service. The vertical marginal gap distance for all samples were subsequently remeasured after the fatigue loading testing. Fracture resistance test was done using universal testing machine. The fracture load was recorded in Newton. Data was collected, tabulated and statistically analyzed. Results: One-way ANOVA test for comparison between the fracture resistance of the four types of all-ceramic crowns revealed that there was a statistically significant difference between mean fracture resistance of different all ceramic materials and techniques used in this study (P-value <0.001). For the marginal gap distance either before or after fatigue cyclic loading; there was a statistically significant difference between the four all ceramic crowns used in this study.Conclusions: CAD/CAM techniques showed better fracture resistance values than pressable techniques, even if the same material was used. The addition of zirconia to lithium disilicate ceramics did not improve the fracture resistance of all ceramic crowns. Pressable processing techniques showed better vertical marginal gap distance than CAD/CAM techniques for both ceramic materials used. Cyclic loading resulted in significant increase in the vertical marginal gap distance for all ceramic crowns using different processing techniques.

915 A Comparison of Endoscopic Submucosal Resection (EMR) vs. Endoscopic Submucosal Dissection (ESD) on Histologic Margins and Pathologic Evaluation for Endoscopically Managed Early Esophageal Adenocarcinoma

INTRODUCTION: Accurate histologic determination is important to determine the completeness of endoscopic resection for esophageal adenocarcinoma (EAC) and gauge risk of recurrence. EMR and ESD are both endoscopic resection techniques used for the treatment of early EAC. ESD advocates believe ESD specimens allow for more precise histopathologic analysis than EMR, but this has never been proven. We aim to determine the effect of EMR vs ESD techniques on histologic analysis in endoscopically treated early EAC. METHODS: This is a retrospective, single center study of EMR and ESD resection specimens with pathologic confirmation of HGD or T1 EAC between 1/15-12/18. Lesions with suspected invasion into the muscularis mucosa or beyond (T2 carcinoma or higher) were excluded. Endoscopic and histologic characteristics were collected. Pathology slides were re-analyzed by a blinded GI pathologist for typical pathologic features. RESULTS: 52 patients with early EAC were analyzed (23 ESD;29 EMR) [Table 1]. ESD-resected tumors were larger compared to those resected by EMR (20 mm [20.0, 28.0] vs 11 mm [9.0, 13.0], P &lt; 0.001) [Table 2]. As per Table 3, EMR specimens were more likely to have positive lateral margins compared to ESD (38% vs 13%, P &lt; 0.005) and have lower confidence in determining lateral margins. Reasons for lower confidence in the EMR group included cautery artifact (37.9%) and difficulty in orientation (20.7%). When accounting for differences in specimen thickness, EMR had a higher percentage of cauterized tissue per total tissue thickness (11.8% vs 3.9%, P &lt; 0.001). EMR specimens had cautery effect abutting the lesion while ESD did not (0 μm vs 2259 μm distance of lesion from nearest cautery, P = 0.001). Cautery effect was more likely to interfere with margin evaluation in EMR (38% vs 13%, P = 0.04). ESD specimens were well-oriented compared to EMR (P = 0.011). EMR and ESD had no difference in positive vertical margins (7% vs 9%, P = 0.33), lymphovascular invasion (P = 0.11), or submucosal invasion (P = 0.62). CONCLUSION: Cautery effect and the inability to orient the specimens appropriately play a role in limiting the evaluation of EMR specimens. EMR and ESD had similar rates of positive vertical margins but rates of positive lateral margins were significantly higher in EMR, despite a smaller lesion size resected with EMR. We postulate that this is a limitation of EMR technique and there is a certain lateral size that is unsuitable for EMR as it may not be able to resect enough of a “normal” margin to the tumor compared to ESD.

Revising the definition of vertical margin involvement following endoscopic polypectomy may reduce unnecessary surgery in patients with malignant colorectal polyps.

Background and Study AimsEndoscopically resected malignant colorectal polyps (MCPs) present a dilemma regarding whether the risk of residual disease justifies a major bowel resection. Overtreatment is common, and the vast majority of patients who undergo resection have no residual tumor. The aim of this study was to investigate whether revising the definition of vertical margin involvement following MCP polypectomy could reduce unnecessary surgery.Patients and MethodsThis was a cohort study of consecutive patients with MCPs treated at a tertiary hospital between 2004 and 2018. Data on demographics, index colonoscopy, polyp pathology, and any subsequent surgical resection were analyzed. Polypectomy resection margins were reviewed and measured to the nearest decimal place. The ability of existing guidelines (requiring a margin clearance of ≥ 1 mm) to predict residual disease was compared to a revised version requiring a margin clearance of ≥ 0.1 mm.ResultsA total of 129 patients with an MCP were included. Of these 129 patients, 77 (60%) underwent surgical resection, of which 62 (81%) had no residual tumor. Existing guidelines, requiring a margin clearance of ≥ 1 mm, classified 28 patients as being at “low risk” for residual disease. Of these, four underwent surgery, but none had residual tumor (P = 0.031). Revised guidelines, requiring a margin clearance of ≥ 0.1 mm, classified 44 patients as “low risk.” Of these, in the 13 that had surgery, no residual tumor was found (P = 0.003).ConclusionsRevising the definition of vertical margin involvement leads to more patients being correctly classified as being at low risk of residual disease. This has the potential to reduce unnecessary surgery in patients with MCPs.

Resectability of Rectal Neuroendocrine Tumors Using Endoscopic Mucosal Resection with a Ligation Band Device and Endoscopic Submucosal Dissection.

Background Rectal neuroendocrine tumors (NETs) < 10 mm in diameter, limited to the submucosa without local or distant metastasis, can be treated endoscopically. Endoscopic mucosal resection with a ligation band device (EMR-L) and endoscopic submucosal dissection (ESD) have been employed to resect rectal NETs. We evaluated and compared the clinical outcomes of EMR-L and ESD for endoscopic resection of rectal NETs G1 < 10 mm in diameter. Methods We conducted a retrospective study of 82 rectal NETs in 82 patients who underwent either EMR-L or ESD. Therapeutic outcomes (en bloc resection and complete resection rates), procedure time, and procedure-related adverse events were evaluated. Additionally, we measured the distance of the lateral and vertical margins from the border of the tumor in pathologic specimens and compared the resectability between EMR-L and ESD. Results Sixty-six lesions were treated using EMR-L and 16 using ESD. En bloc resection was achieved in all patients. The complete resection rate with EMR-L was significantly higher than that with ESD (95.5% vs.75.0%, p = 0.025). The prevalence of vertical margin involvement was significantly higher in the ESD group than in the EMR-L group (12.5% vs. 0%, p = 0.036), and ESD was more time consuming than EMR-L (24.21 ± 12.18 vs. 7.05 ± 4.53 min, p < 0.001). The lateral and vertical margins were more distant in the EMR-L group than in the ESD group (lateral margin distance, 1661 ± 849 vs. 1514 ± 948 μm; vertical margin distance, 277 ± 308 vs. 202 ± 171 μm). Conclusions EMR-L is more favorable for small rectal NETs with respect to therapeutic outcomes, procedure time, and technical difficulties. Additionally, EMR-L enables achievement of sufficient vertical margin distances.

Новые подходы к методике трансуретрального удаления опухолей мочевого пузыря большого размера единым блоком

to develop optimal techniques of en-bloc resection of large non-muscle invasive bladder tumors, determine the proper method of specimen extraction and assess the quality of specimens obtained by different techniques. A total of 12 patients with primary cT1 bladder cancer underwent transurethral en-bloc resection between January 2018 and March 2019 were enrolled into the study. Tumor size ranged from 3.5 cm to 6.2 cm. For removal and extraction of large bladder tumors using thulium fiber en-bloc laser three different techniques were developed: "swiss cheese technique", "crown and root technique" and "three steps technique" technique". The main pathologic criteria used for assessment of removal technique were tumor grade (G), depth of invasion (T), presence of carcinoma in situ (CIS), variant histology (VH), lymphovascular invasion (LVI), presence of detrusor muscle. Additional criteria were horizontal and vertical resection margin, subclassification of T1-stage and presence of focal necrosis in tumor. Among the techniques developed and tested, the best quality of specimens for morphological evaluation was obtained using the combined "crown and root technique". First step is electroresection of the exophytic part of the tumor into pieces, and the next step is en-bloc laser resection (using thulium fiber or holmium laser) of the tumor base. Overall, the quality of all specimens obtained using three techniques met the current requirements of pathologic study. En-bloc resection techniques of large bladder tumors allow obtaining specimen suitable for proper morphological evaluation and correct tumor staging. Further studies are required to evaluate the impact of these techniques on long-term results of treatment options.

Additional surgery after endoscopic submucosal dissection for colorectal cancer: a review of 53 cases.

Endoscopic submucosal dissection (ESD) allows the en bloc resection of tumors and is particularly indicated for T1 colorectal cancer. The number of patients undergoing additional surgery after colorectal ESD is increasing. This study aimed to retrospectively evaluate the efficacy and long-term outcomes in patients with additional surgery. Of 1018 patients who underwent colorectal ESD in our hospital between February 2010 and July 2018, 53 patients who underwent additional surgery in our hospital were retrospectively analyzed and investigated for their clinicopathological characteristics. The need for additional surgery was determined by a pathological examination according to the guideline [1]. In total, 53 patients (24 men, 29 women; mean age, 68.2years; mean tumor diameter, 30.5mm) were included. Laparoscopic surgery was performed in 47 (88.7%) patients. Liver metastases were preoperatively observed in one patient, for whom hepatectomy was simultaneously performed. All procedures included pathological R0 resection. Postoperative complications occurred in 9 (17.0%) patients. There were no complications requiring reoperation. Fifteen (28.3%) patients had a positive vertical margin; of these patients, residual tumor was observed in the resected specimens of two (13.3%) patients. Eight patients (15.1%) had lymph node metastasis (LNM): four (25.0%) and four (10.8%) of 16 and 37 patients with and without vascular invasion, respectively. Eleven patients (20.8%) had grade 2 or 3 tumor budding, and four (36.4%) of these had LNM. Postoperative recurrence was observed in two (3.8%) patients. Additional surgery after ESD for T1 colorectal cancer was effective and had good long-term outcomes.

Endoscopic Submucosal Dissection of Early Gastric Cancer with Mixed-Type Histology: A Systematic Review.

Endoscopic submucosal dissection (ESD) criteria are histologically categorized by early gastric cancer (EGC) with differentiated- and undifferentiated-type histology. However, EGC is histologically heterogenous and there have been no separate criteria for EGC with mixed-type histology [EGC-MH; differentiated-type predominant EGC mixed with an undifferentiated component (EGC-MD) or undifferentiated-type predominant EGC mixed with a differentiated component (EGC-MU)]. Moreover, therapeutic outcomes of ESD for EGC-MH have not been clearly described. This study aimed to evaluate the feasibility of ESD for EGC-MH. We searched core databases for specific inclusion factors: patients with EGC-MH, intervention of ESD, and at least one of the following outcomes: rate of en bloc, complete, curative resection, recurrence, procedure-related adverse event, lymphovascular invasion (LVI), or lymph node metastasis (LNM) that enabled evaluation of feasibility of ESD. A total of eight (systematic review) and four studies (meta-analysis) were included. There was no robustness in age, location, or morphology of EGC-MH. Moderately differentiated adenocarcinoma was frequent in pre-ESD biopsy. EGC-MH showed larger size, deeper invasion, and higher rates of LVI/LNM than pure-type EGC. Total en bloc, complete resection, and curative resection rates were 94.6% (95% confidence interval 86.6-97.9%), 77.8% (57.9-89.9%), and 55.1% (50.4-59.6%), respectively. There was no LNM or extra-gastric recurrence after ESD if the EGC-MD met the curative resection criteria. However, the EGC-MD itself was a risk factor for non-curative resection. (Margin positivity was the most common reason.) CONCLUSIONS: Although ESD seems to be technically feasible, inaccurate prediction of lateral or vertical margin leads to lower curative resection rate. Application of more strict indication is needed for EGC-MH.

Analysis on risk factors of positive vertical resection margin after endoscopic treatment of rectal neuroendocrine tumors

Objective: To analyze the risk factors of positive vertical resection margin of the postoperative specimens after endoscopic treatment of rectal neuroendocrine tumors (NET). Methods: A case-control study was performed. Clinical data of patients with rectal NET (G1) undergoing endoscopic treatment between January 2015 and June 2018 at the Department of Gastroenterology, Beijing Tsinghua Changgung Hospital were retrospectively collected. Inclusion criteria: cases underwent endoscopic mucosal resection (EMR) or endoscopic submucosal dissection (ESD), whose mucosal specimens were pathologically confirmed as NET, and NET was confined to the rectum by nuclide imaging examination before endoscopic treatment. Those with incomplete clinical data or follow-up data were excluded. Resected specimen was fixed and sliced every 2 mm, and when tumor cells were found to infiltrate the vertical cutting edge, the positive vertical margin was defined. Associations of gender, age, resection method, tumor diameter, lesion morphology (nodular lesions, biopsy or post-treatment scar-like changes), mitotic figure, Ki-67 index, etc. and positive vertical margin were analyzed. Univariate analysis was performed using binary logistic analysis and multivariate analysis was performed using logistic regression model. Results: A total of 133 patients with rectal NET were enrolled, including 93 males and 40 females, with an average age of (50.0±10.7) years. Sixty-four patients received EMR treatment and 3 patients (4.7%) had positive vertical margins. While 69 patients received ESD treatment and 13 (18.8%) had positive vertical margins. After endoscopic treatment, 16 cases (12.0%) were vertical positive margin, including 11 males and 5 females with an average age of (52.4±10.4) years. The lesion diameter was (9.0±4.7) mm. Univariate analysis showed that lesion diameter ≥10 mm (χ(2)=5.575, P=0.018) and scar-like changes (χ(2)=3.894, P=0.048) were significantly associated with positive vertical margin. Multivariate analysis showed that the lesion diameter ≥10 mm (OR=10.136, 95%CI: 2.114 to 48.591, P=0.004) was an independent risk factor for positive vertical margin of the specimen after endoscopic treatment of rectal NET. Conclusion: The diameter of rectal NET ≥10 mm indicates a high risk for positive vertical margin after endoscopic treatment.

Clinical short-term and long-term efficacy of endoscopic submucosal dissection in the treatment of early low rectal cancer and precancerous lesions

Objective: To evaluate the short-term and long-term efficacy of endoscopic submucosal dissection (ESD) in the treatment of early low rectal cancer and precancerous lesions. Methods: Inclusion criteria: (1) Distance from the lower margin of tumor to the anal was ≤ 5 cm. (2) Early low rectal cancers were any size rectal epithelial tumors with infiltration depth limited to the mucosa and submucosa, which were diagnosed by postoperative pathology as high-grade intraepithelial neoplasia or adenocarcinoma of the rectum with infiltration depth of intramucosal or submucosal cancer (M or SM stage). (3) Precancerous lesions included adenoma and low-grade intraepithelial neoplasia of the rectum. (4) Patients received ESD treatment. Patients with tumor invasion depth over submucosa by pathology were excluded. From January 2008 to January 2018, 63 patients meeting the above criteria in Peking University First Hospital were enrolled in this descriptive cohort study. The disease characteristics, clinical manifestations, pathological types, treatment time, hospitalization time, en bloc resection rate (resection of the whole lesion), complete resection rate (both the horizontal and vertical incision margins were negative), postoperative complications and follow-up results were analyzed. Cummulative survival rate was calculated by Kaplan-Meier. Results: The diameter of the lesion was (29.0±23.4) mm and the distance from the lesion to the anus was (2.7±1.8) cm. The median operation time was 45.0 (range, 10.0 to 360.0) minutes, the median hospitalization time was 3.0 (range, 2.0 to 12.0) days, en bloc resection rate was 100%, complete resection rate was 96.8% (61/63), and 1 case (1.6%) had postoperative bleeding. The follow-up rate was 87.3% (55/63) and the median follow-up time was 57.9 (range, 15.6 to 121.1) months. No local recurrence was found during the follow-up period and the 5-year survival rate was 100%. Conclusion: Short- and long-term efficacy of ESD are quite good in the treatment of patients with early low rectal cancer and precancerous lesions.

Vertical collapse safety margin assessment for steel frames against earthquake-induced loss of column

A quantifiable approach measuring the seismic structural collapse under sudden column removal is proposed using the interaction of the vertical collapse margin ratio (CMRV), the demand-to-capacity ratio (DCR) and the robustness (R). The assessment of CMRV needs the identification of the vertical maximum considered earthquakes. A classification of the ground motions based on the vertical-to-horizontal (V/H) ratios was used to obtain the vertical design spectrum. Six schemes of steel structures with various scenarios of sudden column removal were investigated to extract CMRV, DCR, and R. Then, a nonlinear regression analysis allows finding a general formulation of CMRV. A 15-story steel structure validates the proposed formulation of the CMRV. The two paths for estimating the minimum CMRV (CMRV, min) were the use of the recommended value of DCR and the minimum value of R inside the approximated CMRV expression, and the probabilistic distribution of CMRV, min from the analyses of different beam deformation states. The study of eighteen archetypes with 119 scenarios of sudden column removal reveals the value of the CMRV decreases when the V/H or/and DCR increase. The new maximum values of DCR with respect to R and its precise ranges are found with the use of the contour curves of CMRV, min.

Combination of immersion in saline solution, pocket-creation method, water-jet hydrodissection, and hybrid knife "probe mode" simplifies endoscopic submucosal dissection in giant rectal polyp.

Combination of immersion in saline solution, pocket-creation method, water-jet hydrodissection, and hybrid knife "probe mode" simplifies endoscopic submucosal dissection in giant rectal polyp.

Ligation assisted endoscopic mucosal resection of neuroendocrine tumor of duodenal bulb: a case report with a follow up of 24 months

Duodenal neuroendocrine tumor (NET) is a rare solitary lesion arising from the mucosa and submucosa of the duodenum, which is found incidentally during upper gastrointestinal endoscopy. Eendoscopic Mucosal Resection (EMR) has been the commonly used endoscopic procedure for duodenal carcinoid tumors, but the conventional EMR done to resect duodenal NET s is likely to have positive vertical margins. However, the ligation assisted EMR has recently been shown to be a promising technique for the treatment of duodenal NET that can have a negative free margin. In our study, we present a patient of 51-year-old male, who presented with pain over epigastrium and upper gastrointestinal endoscopy revealed a small submucosal lesion of 10 mm in the duodenal bulb. The endoscopic ultrasound showed the lesion arising from the echo layer three. The biopsy was taken which showed the duodenal NET. The computed tomography of abdomen did not show any evidence of distant metastasis. The EMR of duodenal NET was done by band ligation technique. The biopsy from the resected duodenal lesion confirmed the duodenal NET with the margin free of the tumor. The patient was followed at 6, 12, 18 and 24 months. During the follow up visits, the repeat upper gastrointestinal endoscopy did not show recurrence of the lesion and there was no any evidence of distant metastasis either. Ligation assisted EMR is an acceptable treatment in the hands of expert for small duodenal NET without the evidence of metastasis and can ensure the complete removal of the lesion with vertical free margin.

Mo1226 THE EFFECT OF ENDOSCOPIC MUCOSAL RESECTION (EMR) VS ENDOSCOPIC SUBMUCOSAL DISSECTION (ESD) TECHNIQUE ON HISTOLOGIC MARGINS FOR ENDOSCOPICALLY TREATED EARLY ESOPHAGEAL ADENOCARCINOMA

Both endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) techniques are used for the treatment of early esophageal cancers. ESD has potential advantages including higher en bloc and R0 resection rates, which have been demonstrated for squamous cell carcinomas (ESCC) but data for esophageal adenocarcinoma (EAC) is more limited. Histologic determination of the horizontal and vertical margins is important to determine the completeness of resection and risk of recurrence. Larger tumors, especially those that spread laterally may exceed with limits of en bloc resectability using standard EMR techniques.

Vertical Contracts That Reference Rivals

We study two types of vertical contracts that reference rivals: the “vertical price constraint” (VPC) requires retail prices for a manufacturer’s product to be no higher than for its competitors’ products. The “vertical margin constraint” (VMC) requires retail margins for a manufacturer’s product to be no higher than for its competitors’ products. These agreements are found in the soft drink and cigarette industries, and in travel platforms. With two asymmetric manufacturers, we find that only the larger adopts a VPC in a subgame perfect equilibrium. We also analyze incentive compatibility issues with optional VPC agreements. Apart from leading to increased prices, the VPC leads to lower profits for the smaller manufacturer. In contrast, the VMC leads to lower prices. Under certain conditions, by adopting the VMC, a larger manufacturer will gain enough to compensate the retailer and still be better off, while making its competitor worse off. These two vertical contracts work because they alter the price elasticities of demand that face upstream manufacturers.