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.

Outcomes after endoscopic mucosal resection or esophagectomy for submucosal esophageal adenocarcinoma.

OBJECTIVES: Endoscopic mucosal resection (EMR) is a diagnostic and potentially therapeutic option for patients with submucosal esophageal adenocarcinoma. However, there are significant concerns regarding the risk of lymph node metastasis. Our purpose was to construct a comparative effectiveness analysis comparing recurrence patterns after therapeutic EMR or esophagectomy. METHODS: Patients who underwent therapeutic EMR or esophagectomy from 2007 to 2015 with pathologically staged submucosal adenocarcinoma were identified from a departmental database. Cancer-related outcomes were compared among an unmatched as well as a propensity matched cohort. Risk stratification was also used to compare results among those with a low, medium, or high risk of nodal metastasis. RESULTS: Seventy-two patients met criteria for analysis, among whom 23 underwent therapeutic EMR with esophageal preservation and 49 underwent esophagectomy. Median follow-up was 43 months. Patients who underwent esophagectomy had larger, deeper tumors. Esophageal preservation was associated with an increased risk of local recurrence (P = .01), but not distant recurrence (P = .44). After propensity matching, there continued to be no difference in distant recurrence rate (P = .66). In a risk-stratified analysis, low-risk patients showed no recurrences or cancer-related deaths, however, high-risk patients showed a trend toward increased distant recurrence after therapeutic EMR. CONCLUSIONS: Esophageal preservation after therapeutic EMR was associated with an increased risk of local recurrence. Among low-risk patients, either strategy resulted in excellent cancer control. However, among high-risk patients, esophageal preservation showed a trend toward increased distant failure. These findings should prompt further investigation to determine optimal treatment for patients with submucosal esophageal adenocarcinoma.

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.

Self-expandable metal stents (SEMS) can serve as a bridge to surgery or as a definitive therapy in patients with an advanced stage of cancer: clinical experience of a tertiary cancer center.

BACKGROUND: Self-expandable metal stents (SEMS) can be used to relieve benign and malignant colorectal obstruction. AIMS: The aim of this study was to determine the outcomes of SEMS for malignant colorectal obstruction. METHODS: Retrospective review was done of patients who underwent endoscopic SEMS placement from 2001 to 2007. RESULTS: Forty-six patients (23 M), mean age 60 years (range 24-82) underwent endoscopic SEMS placement. Cancer types included: 28 colorectal, and 18 metastatic cancers. The locations of the obstruction were as follows: two in the ascending colon, one in the hepatic flexure, three in the transverse colon, two in the splenic flexure, two in the descending colon, 26 in the sigmoid colon, and ten in the rectum. In 39 of the 46 cases (84.8%), placement of a single SEMS was successful covering the entire strictures, but in seven cases, two of the stents were placed in tandem resulting in adequate overage of stricture. Technical success was achieved in all cases. Clinical success was achieved in 39 out of 46 cases (84.8%). Two perforations were detected immediately and day 5 after SEMS placement, resulting in one death and one emergent surgery. Mean follow-up was 126 days (range 2-1,210). Twenty-eight of the 46 patients (61%) died during the follow-up period with the median overall survival being 3.52 months (95% CI: 2.34-4.41 months). CONCLUSIONS: Placement of SEMS for the treatment of colorectal obstruction is feasible and safe. In our institution, where SEMS are primarily used to palliate terminal disease, technical and clinical success rates were high without significant morbidity and mortality. On long-term follow-up, patients died from their advanced disease with infrequent recurrent obstruction or stent-related complications.

Endoscopic therapy in Barrett's esophagus: when and how?

Endoscopic ablative therapy, and endoscopic mucosal resection (EMR) are the two general types of endoscopic therapies available for the treatment of Barrett's esophagus. The ablative therapies destroy metaplastic tissue, but do not provide a pathology specimen by which to judge the completeness of the ablation. In contrast, EMR provides large tissue specimens that can be examined by the pathologist to determine the character and extent of the mucosal abnormality and, for neoplastic lesions, the depth of involvement and the adequacy of resection. In this article, we discuss the use of endoscopic therapies for Barrett's esophagus presenting with no neoplasia, low and high-grade dysplasia, and early adenocarcinoma.

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.

Duration of the interval between the completion of bowel preparation and the start of colonoscopy predicts bowel-preparation quality.

BACKGROUND: Recent studies suggest that colonoscopies done in the morning have better-quality bowel preparations than those done in the afternoon. OBJECTIVE: We aimed to determine how the duration of the interval between the end of the preparation and the start of the colonoscopy affects preparation quality. DESIGN: We prospectively studied consecutive outpatients who had colonoscopies performed at our hospital within a 3-month period. The time of day when the colonoscopy started and the time interval from the last dose of preparation agent to the start of the colonoscopy were recorded. The endoscopist graded the quality of the preparation in the right side of the colon by using a 5-point visual scale. PATIENTS: We studied 378 patients (96% men, mean age 62.2 years) who received preparations of polyethylene glycol electrolyte-based (PEG) and sodium phosphate (SP) solution (71%), oral PEG and magnesium citrate (23%), or SP alone (6%). RESULTS: Compared with patients whose preparations were graded as 2/3/4 (fair/poor/inadequate), those whose preparations were graded as 0/1 (excellent/good) had a significantly shorter interval between the time of the last preparation agent dose and the start of the colonoscopy (P = .013). LIMITATIONS: We used a nonvalidated scale to assess the quality of bowel preparation. CONCLUSIONS: Bowel-preparation quality varies inversely with the duration of the interval between the last dose of the bowel-preparation agent and the start of colonoscopy. This interval appears to be a better predictor of bowel-preparation quality than the time of day when colonoscopy is performed.