A Gastroenterologist's Approach to the Diagnosis and Management of Gastrointestinal Stromal Tumors.

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal (GI) tract. These tumors have been shown to harbor oncogenic mutations of the c-kit tyrosine kinase receptor or platelet-derived growth factor receptor alpha (PDGFRA). Immunohistochemical analysis of GISTs allows for the differentiation of these tumors from other mesenchymal tumors of the GI tract such as leiomyomas and leiomyosarcomas. All GISTs have the potential to behave in a malignant fashion. Tumor location, size, and mitotic index are factors used to predict the risk of malignant behavior. Endoscopy and endoscopic ultrasound play a critical role in the diagnosis of GISTs and can yield important information to further risk-stratify tumors and determine management. This article provides a gastroenterologist's perspective on the diagnosis and management of GISTs.

Continuing Medical Education Questions: May 2021.

Article Title: Obesity Primer for the Practicing Gastroenterologist.

Barrett's Esophagus after Bimodality Therapy in Patients with Esophageal Adenocarcinoma.

INTRODUCTION: Barrett's esophagus (BE) may be present in patients with esophageal adenocarcinoma (EAC) after bimodality therapy (BMT). There is no specific guidance for follow-up of these patients with regard to the presence of BE or dysplasia. In this study, we assessed the outcomes of patients who, after BMT, had BE and those who did not. METHOD: Patients with EAC who had BMT were identified and analyzed retrospectively in two groups, with and without BE. We compared patient characteristics and outcome variables (local, distant, and no recurrence). RESULTS: Of 228 patients with EAC, 68 (29.8%) had BE before BMT. Ninety-eight (42.9%) had BE after BMT, and endoscopic intervention was done in 11 (11.2%). With a median follow-up of 37 months, the presence of post-BMT BE was not significantly associated with overall survival (OS) and local recurrence-free survival (LRFS). Similarly, endoscopic intervention was not significantly associated with OS and LRFS. Fifty (73.5%) patients with BE before BMT had BE after BMT (p < 0.0001). CONCLUSION: The presence of BE after BMT was not associated with increased risk of local recurrence. The local recurrence rate was not influenced by endoscopic intervention. Prospective studies are warranted to generate guidance for intervention, if necessary, for this group of EAC patients.

Low rate of postpolypectomy bleeding among patients who continue thienopyridine therapy during colonoscopy.

BACKGROUND & AIMS: It is not clear whether the cardiovascular risk of discontinuing treatment with antiplatelet agents, specifically the thienopyridines, before elective colonoscopy outweighs the risks of postpolypectomy bleeding (PPB). We studied the rate of PPB in patients who continue thienopyridine therapy during colonoscopy. METHODS: We performed a prospective study of 516 patients not taking warfarin who received polypectomies during elective colonoscopies; 219 were receiving thienopyridines, and 297 were not (controls). The occurrence of immediate PPB and delayed PPB was recorded. Delayed PPB was categorized as clinically important if it resulted in repeat colonoscopy, hospitalization, or blood transfusion. RESULTS: Patients receiving thienopyridines were older and had significantly more comorbid diseases than controls; the mean number of polyps removed per patient was significantly higher (3.9 vs 2.9) in the thienopyridine group. Immediate PPB developed in 16 patients in the thienopyridine group (7.3%) and in 14 in the control group (4.7%, P = .25). Among patients who completed a 30-day follow-up analysis (96% of patients enrolled), clinically important, delayed bleeding occurred in 2.4% of patients receiving thienopyridines and in none of the controls (P = .01). All PPB events in both groups were resolved without surgery, angiography, or death. CONCLUSIONS: Although a significantly higher percentage of patients who continue thienopyridine therapy during colonoscopy and polypectomy develop clinically important delayed PPB than patients who discontinue therapy, the rate of PPB events is low (2.4%), and all are resolved without sequelae. The risk for catastrophic cardiovascular risks among patients who discontinue thienopyridine therapy before elective colonoscopies could therefore exceed the risks of PPB. ClinicalTrials.gov, Number NCT01647568.

Small-bowel endoscopy core curriculum.

This is one of a series of documents prepared by the ASGE Training Committee. This curriculum document contains recommendations for training, intended for use by endoscopy training directors, endoscopists involved in teaching endoscopy, and trainees in endoscopy. It was developed as an overview of techniques currently favored for the performance and training of small-bowel endoscopy and to serve as a guide to published references, videotapes, and other resources available to the trainer. By providing information to endoscopy trainers about the common practices used by experts in performing the technical aspects of the procedure, the ASGE hopes to improve the teaching and performance of small-bowel endoscopy.

The rate of post-polypectomy bleeding for patients on uninterrupted clopidogrel therapy during elective colonoscopy is acceptably low.

BACKGROUND: We do not routinely discontinue clopidogrel before colonoscopy because we have judged the cardiovascular risks of that practice to exceed the risks of post-polypectomy bleeding (PPB). AIMS: The aim of this study was to compare the rates of PPB for clopidogrel users and non-users. METHODS: We performed a retrospective, case-control study of patients who had colonoscopic polypectomy at our VA hospital from July 2008 through December 2009. We compared the frequency of delayed PPB (within 30 days) for patients on uninterrupted clopidogrel therapy with patients not taking clopidogrel. To minimize confounding from differences between groups in conditions that might contribute to PPB, propensity scoring was used to match clopidogrel users with controls based on numerous factors including age, aspirin use, number and size of polyps removed. RESULTS: A total of 1,967 patients had polypectomy during the study period; 118 were on clopidogrel and 1,849 were not. Logistic regression analysis revealed no significant difference in frequency of PPB between clopidogrel users and non-users (0.8% vs. 0.3%, P = 0.37, unadjusted OR = 2.63, 95% CI 0.31-22). Matched analyses using propensity scoring also revealed no significant difference in PPB rates between clopidogrel users and non-users (0.9% vs. 0%, P = 0.99). CONCLUSIONS: The delayed PPB rate for our patients on clopidogrel was less than 1%, and PPB rates did not differ significantly between users and non-users. Our conclusions are limited by differences in therapeutic methodology between the groups, and our findings are most applicable to small polyps (<1 cm). We speculate that cardiovascular risks of routinely discontinuing clopidogrel before elective colonoscopy may exceed any excess risk of PPB.

Chromoendoscopy.

Chromoendoscopy involves the use of stains or dyes during endoscopy to improve the visualization and characterization of the gastrointestinal mucosa. Its main clinical application is the detection of dysplasia or early cancer of the gastrointestinal tract in individuals with pre-malignant conditions or hereditary and environmental factors that predispose them to cancer. The utility of chromoendoscopy has been mostly studied in squamous cell carcinoma of the esophagus, Barrett's esophagus, gastric cancer, colorectal polyps, and chronic ulcerative colitis. Although chromoendoscopy has been shown to be feasible and safe, several limitations have prevented its widespread use in endoscopy. Despite this, chromoendoscopy remains a useful adjunct to standard white light endoscopy in the visualization of mucosal lesions, which may potentially improve tissue diagnosis and impact patient care.

Yield of tissue sampling for subepithelial lesions evaluated by EUS: a comparison between forceps biopsies and endoscopic submucosal resection.

BACKGROUND: In most circumstances, subepithelial tumors lack distinct endoscopic and ultrasonographic features. Consequently, definitive diagnosis usually requires tissue acquisition and pathologic confirmation. Establishing a tissue diagnosis is difficult because the yield of forceps biopsies is low. However, prospective data evaluating tissue sampling techniques for subepithelial lesions are currently lacking. OBJECTIVE: Our purpose was to prospectively determine the diagnostic yield of endoscopic submucosal-mucosal resection (ESMR) compared with forceps biopsy for lesions limited to the submucosa (third endosonographic layer) of the GI tract. DESIGN: A prospective head-to-head comparison was performed. SETTING: The study was performed in a tertiary care hospital. PATIENTS: Study patients were 23 adults with subepithelial lesions limited to the submucosa. INTERVENTION: All submucosal lesions underwent forceps biopsy followed by endoscopic submucosal resection. Biopsy specimens were obtained with large-capacity "jumbo" forceps. A total of 4 double passes (8 biopsy specimens) were collected from each lesion with use of the bite-on-bite technique. Endoscopic resection was then performed with an electrosurgical snare or cap-fitted endoscopic mucosal resection device. MAIN OUTCOME MEASUREMENT: The main outcome measurement was the diagnostic yield of biopsy forceps compared with endoscopic submucosal resection. RESULTS: Twenty-three patients with lesions limited to the submucosa were identified by endoscopic ultrasonography. All lesions underwent forceps biopsy followed by ESMR. The diagnostic yield of the jumbo forceps biopsy was 4 of 23 (17%), whereas the diagnostic yield of ESMR was 20 of 23 (87%) (P = .0001, McNemar test). CONCLUSION: In the evaluation of subepithelial lesions limited to the submucosa, ESMR has a significantly higher diagnostic yield than jumbo forceps biopsy with use of the bite-on-bite technique.