<b>Background and study aims:</b> There is a risk for lymph node metastases (LNM) after endoscopic resection of early esophageal adenocarcinoma (EAC). The aim of this study was to develop and internally validate a prediction model that estimates the individual metastases risk in patients with pT1b EAC. <b>Patients and methods:</b> This is a nationwide, retrospective, multicenter cohort study. Patients with pT1b EAC and treated with endoscopic resection and/or surgery between 1989 and 2016 were included. Primary endpoint was the presence of LNM in surgical resection specimen or the detection of metastases during follow-up. All resection specimens were histologically reassessed by specialized gastrointestinal pathologists. Subdistribution hazard regression analysis was used to develop a prediction model. The discriminative ability of this model was assessed using the c-statistic. <b>Results:</b> 248 patients with pT1b EAC were included. Metastases were seen in 78 patients, and the 5-year cumulative incidence was 30.9% (95% CI 25.1%-36.8%). The risk for metastases increased with submucosal invasion depth (subdistribution hazard ratio [SHR] 1.08, 95% CI 1.02-1.14, for every increase of 500 μm), for tumors with lymphovascular invasion (SHR 2.95, 95% CI 1.95-4.45) and for larger tumors (SHR 1.23, 95% CI 1.10-1.37, for every increase of 10 mm). The model demonstrated a good discriminative ability (c-statistic 0.81, 95% CI 0.75-0.86). <b>Conclusions:</b> One third of patients with pT1b EAC experienced metastases within 5 years. The probability for developing post resection metastases can be estimated with a personalized predicted risk score incorporating tumor invasion depth, tumor size and lymphovascular invasion. This model needs to be externally validated before implementation into clinical practice.

Background In early (T1) oesophageal adenocarcinoma (OAC), the histological profile of an endoscopic resection specimen plays a pivotal role in the prediction of lymph node metastasis and the potential need for oesophagectomy with lymphadenectomy. Objective To evaluate the inter-observer agreement of the histological assessment of submucosal (pT1b) OAC. Methods Surgical and endoscopic resection specimens with pT1b OAC were independently reviewed by three gastrointestinal pathologists. Agreement was determined by intraclass correlation coefficient for continuous variables, and Fleiss' kappa (κ) for categorical variables. Bland–Altman plots of the submucosal invasion depth were made. Results Eighty-five resection specimens with pT1b OAC were evaluated. The agreement was good for differentiation grade (κ=0.77, 95% confidence interval (CI) 0.68–0.87), excellent for lymphovascular invasion (κ=0.88, 95% CI 0.76–1.00) and moderate for submucosal invasion depth using the Paris and Pragmatic classifications (κ=0.60, 95% CI 0.49–0.72 and κ=0.42, 95% CI 0.33–0.51, respectively). Systematic mean differences between pathologists were detected for the measurement of submucosal invasion depth, ranging from 297 µm to 602 µm. Conclusions A substantial discordance was found between pathologists for the measurement of submucosal invasion depth in pT1b OAC. Differences may lead to an over- or underestimation of the lymph node metastasis risk, with grave implications for the treatment strategy. Review by a second gastrointestinal pathologist is recommended to improve differentiating between a favourable and an unfavourable histological profile.

IntroductionThe incidence of esophageal adenocarcinoma (EAC) has increased rapidly over the last three decades [1,2]. Although therapeutic protocols for early-and late-stage esophageal tumors have been well defined, treatment strategies for clinicalstage T2N0M0 tumors (cT2N0M0) are subject to debate owing to the relative inaccuracy of endoscopic ultrasound (EUS) staging, with profound implications in overstaged patients [3 -6]. A minimally invasive endoscopic resection is recommended for cT1 EACs. Only when the endoscopic resection specimen shows histological characteristics associated with an increased risk of lymph node metastasis (LNM) will a surgical resection follow [7 -9]. For locally advanced tumors (cT2 -4), however, neoad-

Background and Aims: Recently, the 360 Express radiofrequency ablation balloon catheter (360 Express, Med-tronic, Minneapolis, Minn, USA) has replaced the traditional system for circumferential radiofrequency ablation (RFA) of Barrett's esophagus (BE). The aim was to compare 3 different ablation regimens for the 360 Express.Methods: An international multicenter noninferiority randomized controlled trial was conducted in which pa-tients with a BE (2-15 cm) with dysplasia or early cancer were randomly assigned to the standard (1 10 J/ cm 2 -clean-1 10 J/cm 2 ), simple-double (2 10 J/cm 2 -no clean), or simple-single ablation regimen (1 10 J/ cm 2 -no clean). The primary outcome was the percentage endoscopically visual BE regression at 3 months. Sec-ondary outcomes were procedure time, adverse events, and patient discomfort.Results: Between September 2015 and October 2017, 104 patients were enrolled. The simpledouble ablation arm was closed prematurely because of a 21% stenosis rate. The trial continued with the standard (n Z 37) and simple-single arm (n Z 38). Both arms were comparable at baseline. Noninferiority of the simple-single arm could not be demonstrated: BE regression was 73% in the simple-single arm versus 85% in the standard arm; the median difference was 13% (95% confidence interval, 5%-23%). The procedure time was significantly longer in the standard arm (31 vs 17 minutes, P < .001). Both groups were comparable with regard to adverse events and patient discomfort.Conclusions: This randomized trial shows that circumferential RFA with the 360 Express using the simple-double ablation regimen results in an unacceptable high risk of stenosis. Furthermore, the results suggest that a single ablation at 10 J/cm 2 results in inferior BE regression at 3 months. We therefore advise using the standard ablation regimen (1 10 J/cmclean-1 10 J/cm ) for treatment of BE using the 360 Express.