Endoscopic screening and surveillance for gastric cancer: challenges and opportunities

Endoscopic screening is premised on the detection of pre-symptomatic, early-stage gastric neoplasia that enables curative resection. Endoscopic screening reduces gastric cancer mortality in high-incidence countries but is highly resource-intensive. Endoscopic surveillance of high-risk subgroups of intestinal metaplasia has gained traction in low and intermediate-incidence countries, and emerging evidence suggests that risk-stratified endoscopic surveillance may facilitate timely detection of cancer. However, outcome-based evidence is required to support its adoption. Yet the impact of an endoscopy-based strategy may well lie in heralding a paradigm that regards every routine diagnostic gastroscopy as an opportunity to screen for GC. Endoscopic surveillance also renders gastric intestinal metaplasia a de facto disease, and the ramification of this needs to be further elucidated.

Quality indicators in the endoscopic detection of gastric cancer

Gastroscopy is the reference standard for the diagnosis of gastric cancer, but it is operator-dependent and associated with missed gastric cancer. The proliferation of gastroscopic examinations, increasingly for the screening and detection of subtle premalignant lesions, has motivated scrutiny of quality in gastroscopy. The concept of a high-quality endoscopic examination for the detection of superficial gastric neoplasia has been defined by expert guidelines to improve mucosal visualization, engender a systematic examination process and detect superficial neoplasia. This review discusses the evidence supporting the components of a high-quality diagnostic gastroscopic examination in relation to the detection of gastric cancer, and their potential role as procedural quality indicators to drive a structured improvement in clinically meaningful outcomes.

Academy of Medicine, Singapore clinical guideline on endoscopic surveillance and management of gastric premalignant lesions

Gastric cancer (GC) has a good prognosis, if detected at an early stage. The intestinal subtype of GC follows a stepwise progression to carcinoma, which is treatable with early detection and intervention using high-quality endoscopy. Premalignant lesions and gastric epithelial polyps are commonly encountered in clinical practice. Surveillance of patients with premalignant gastric lesions may aid in early diagnosis of GC, and thus improve chances of survival. An expert professional workgroup was formed to summarise the current evidence and provide recommendations on the management of patients with gastric premalignant lesions in Singapore. Twenty-five recommendations were made to address screening and surveillance, strategies for detection and management of gastric premalignant lesions, management of gastric epithelial polyps, and pathological reporting of gastric premalignant lesions.

A prospective randomized tandem gastroscopy pilot study of linked color imaging versus white light imaging for detection of upper gastrointestinal lesions

BACKGROUND AND AIM

Gastrointestinal (GI) lesions may have subtle morphological changes. Linked color imaging (LCI) combines narrow-band wavelength light and white light imaging (WLI) in appropriate balance to enhance lesion detection. We compared the detection rates of upper GI lesions using LCI and WLI.

METHOD

Patients were randomized in a 1:1 ratio to receive tandem gastroscopy with WLI inspection followed by LCI, or vice versa. Endoscopic examination was performed using the EG-L590ZW gastroscope and the LASEREO endoscope system (Fujifilm Co., Tokyo, Japan). Histology was reported by a specialist GI pathologist blinded to the technique of lesion detection and was used as the gold standard for diagnosis.

RESULTS

Ninety patients (mean age 66.8 years, 51.5% male patients) were randomized to either LCI examination first followed by WLI (LCI-WLI), or vice versa (WLI-LCI). An 18.9% of gastroscopies in the study were for surveillance of previously known gastric cancer precursors. Ten patients (11.1%) had a history of Helicobacter pylori infection. There was no significant difference in the time taken for examination under LCI (311 ± 96 s) and WLI (342 ± 86 s) (P = 0.700). LCI detection rates were higher than WLI detection rates for gastric cancer precursors such as atrophic gastritis (2.19% vs 0.55%) (P < 0.01) and intestinal metaplasia (19.73% vs 7.67%) (P < 0.01). Both sensitivity (82.74% vs 50.96%) and specificity (98.71% vs 96.10%) of LCI were higher than WLI for detection of upper GI lesions.

CONCLUSIONS

Linked color imaging had better detection rates, sensitivity, and specificity for detection of upper GI lesions compared with WLI.

Clinical guidance on endoscopic management of colonic polyps in Singapore

Colonoscopy with endoscopic resection of detected colonic adenomas interrupts the adenoma-carcinoma sequence and reduces the incidence of colorectal cancer and cancer-related mortality. In the past decade, there have been significant developments in instruments and techniques for endoscopic polypectomy. Guidelines have been formulated by various professional bodies in Europe, Japan and the United States of America, but some of the recommendations differ between the various bodies. An expert professional workgroup under the auspices of the Academy of Medicine, Singapore, was set up to provide guidance on the endoscopic management of colonic polyps in Singapore. A total of 23 recommendations addressed the following issues: accurate description and diagnostic evaluation of detected polyps; techniques to reduce the risk of post-polypectomy bleeding and delayed perforation; the role of specific endoscopic resection techniques; the histopathological criteria for defining endoscopic cure; and the role of surveillance colonoscopy following curative resection.

Evaluation of symptomatic esophagogastric junction outflow obstruction

BACKGROUND AND AIM

Esophagogastric junction outflow obstruction (EGJOO) may be due to anatomical abnormalities, but it is unclear how to evaluate them after high-resolution manometry. We aimed to determine (i) clinical and high-resolution manometry parameters differentiating anatomical EGJOO from functional EGJOO, (ii) investigations chosen and yield for anatomical EGJOO, and (iii) clinical outcomes of functional EGJOO.

METHODS

Medical records of consecutive patients with symptomatic EGJOO from February 2012 to December 2015 were reviewed. EGJOO was defined as anatomical if investigations identified a macroscopic or microscopic pathology accounting for EGJOO.

RESULTS

Forty of 292 (13.7%) had EGJOO, of which 6/40 (15%) had anatomical EGJOO (two PPI-responsive esophageal eosinophilia, two infiltrating cancers, and two external compressions). Anatomical EGJOO was more likely to present with dysphagia (100% vs 29.4%, P = 0.001) and less likely with regurgitation (0% vs 41.2%, P = 0.05). Anatomical EGJOO had higher frequencies of premature contraction (50% vs 5.9%, P = 0.003) and lower mean values of distal latency (5.6 +/- 1.3 vs 6.7 +/- 1.2, P = 0.004). Computed tomography scans revealed 50% (3/6) of etiologies of anatomical EGJOO. Approximately, 73.5% (25/34) of patients with functional EGJOO had spontaneous resolution of their symptoms. One underwent pneumatic dilatation with symptom resolution while remaining eight with persistent symptoms were attributed to gastroesophageal reflux disease.

CONCLUSION

Anatomical causes are present in 15% of EGJOO. Evaluation is warranted especially in patients presenting with dysphagia. Esophageal biopsies, barium swallows, computed tomography scans, and endoscopic ultrasound are complementary in EGJOO evaluation. In patients with non-obstructive symptoms and no anatomical etiologies, monitoring for spontaneous resolution is an option.

Recent advances in the link between physical activity, sedentary behavior, physical fitness, and colorectal cancer

Physical inactivity is a well-established risk factor for colorectal cancer (CRC). Recent studies have characterized physical activity (PA), sedentary behavior, and cardiorespiratory fitness as distinct, interrelated constructs that influence the risk of CRC and related outcomes. PA levels required to confer protection against CRC may be higher than previously thought. Sedentary behavior, defined as time spent sitting, increases CRC risk independent of PA and may require novel interventions distinct from those targeting PA. Finally, cardiorespiratory fitness is inversely associated with CRC risk and mortality and may provide a potential tool for risk stratification and intervention.

Narrow-band imaging and white-light endoscopy with optical magnification in the diagnosis of dysplasia in Barrett's esophagus: results of the Asia-Pacific Barrett's Consortium

OBJECTIVE

The advent and utility of new endoscopic imaging modalities for predicting the histology of Barrett's esophagus (BE) in real time with high accuracy appear promising and could potentially obviate the need to perform random biopsies where guidelines are poorly adhered to. We embarked on evaluating the performance characteristics of white-light endoscopy with magnification (WLE-z), narrow-band imaging with magnification (NBI-z) and a combination of both modalities.

DESIGN

This was a prospective online study with 28 endoscopists from 11 countries (Asia-Pacific region) participating as assessors. In total, 35 patients with BE were assessed using 150 slides from WLE-z and NBI-z randomly arranged using a simple classification with corresponding histology. The overall Accuracy (Acc), Sensitivity (Sn), Specificity (Sp), Positive Predictive Value (PPV), and Negative Predictive Value (NPV) of WLE-z, NBI-z and a combination of both were calculated.

RESULTS

The overall Acc for WLE-z and NBI-z images was 87.1 % and 88.7 %, respectively. When images from the two modalities were placed side by side, the Acc increased to 90.3 %. The Sn, Sp, PPV, and NPV of WLE-z were 48 %, 92 %, 45 %, and 93 % while with NBI-z, these improved to 89 %, 89 %, 56 %, and 98 %, respectively. When both imaging modalities were viewed together, they improved further to 93 %, 90 %, 61 %, and 99 %.

CONCLUSION

The high NPV (99 %) when both WLE-z and NBI-z were used simultaneously indicates that areas with regular appearance that are diagnosed with confidence can effectively be left alone and not biopsied when performed at a skilled resourced center. This approach could potentially lead to a paradigm shift of how patients with BE are assessed.

Distribution of body fat and its influence on esophageal inflammation and dysplasia in patients with Barrett's esophagus

BACKGROUND & AIMS

Increased waist circumference and visceral fat are associated with increased risk of Barrett's esophagus (BE) and esophageal adenocarcinoma. This association might be mediated by mechanical and endocrine mechanisms. We investigated the distribution of fat in subjects with BE and its association with esophageal inflammation and dysplasia.

METHODS

We collected data from 50 BE cases and 50 controls (matched for age and sex, identified from a radiology trauma database) seen at the Mayo Clinic in 2009. Abdominal (subcutaneous and visceral) and gastroesophageal junction (GEJ) fat area was measured using computed tomography with standard techniques. Esophageal inflammation (based on a histologic score) and dysplasia grade were assessed from esophageal biopsies of BE cases by a gastrointestinal pathologist. Conditional logistic regression was used to assess the association of body fat depot area with BE status, esophageal inflammation, and dysplasia.

RESULTS

All BE subjects had controlled reflux symptoms without esophagitis, based on endoscopy. The GEJ fat area (odds ratio [OR], 6.0; 95% confidence interval [CI], 1.3-27.7; P = .02), visceral fat area (OR, 4.9; 95% CI, 1.0-22.8; P = .04), and abdominal circumference (OR, 9.1; 95% CI, 1.4-57.2; P = 0.02) were associated with BE, independent of body mass index (BMI). The subcutaneous fat area was not associated with BE. Visceral and GEJ fat were significantly greater in BE subjects with esophageal inflammation (compared with those without, P = .02) and high-grade dysplasia (compared with those without, P = .01), independent of BMI.

CONCLUSIONS

GEJ and visceral fat are associated with BE, and with increased esophageal inflammation and high-grade dysplasia in BE subjects, independent of BMI. Visceral fat therefore might promote esophageal metaplasia and dysplasia.

Weakly acidic reflux

The advent of multichannel intraluminal impedance-pH (MII-pH) monitoring has generated interest in the role of weakly acidic reflux in persistent symptoms in patients with gastroesophageal reflux disease (GERD). Emerging evidence suggests that MII-pH may be superior to conventional pH testing under certain circumstances in the detection of reflux and expert opinions have been put forth advocating a central role for pH impedance monitoring in the detection of GERD. However the clinical relevance of an impedance-based diagnosis of reflux and its impact on clinically relevant outcomes is less clear. This review appraises the role of weakly acidic reflux in health and in GERD patients and the clinical utility of detecting weakly acidic reflux in the management of GERD.

Microfabricated reaction and separation systems

Over the past year there have been a number of recent advances in the fields of miniaturized reaction and separation systems, including the construction of fully integrated 'lab-on-a-chip' systems. Microreactors, which initially targeted DNA-based reactions such as the polymerase chain reaction, are now used in several other chemical and biochemical assays. Miniaturized separation columns are currently employed for analyzing a wide variety of samples including DNA, RNA, proteins and cells. Although significant advances have been made at the component level, the realization of an integrated analysis system still remains at the early stages of development.