Screening for Barrett's Esophagus

Microflora composition in the gastrointestinal tract in patients with Barrett's esophagus

Background

The incidence of esophageal adenocarcinoma (EAC) has been increasing over the last 40 years. While Barrett's esophagus is a known risk factor for the development of EAC, the role of the microflora in the development of EAC is still largely unknown and is being investigated further by multiple centers. Our goal was to identify trends in microflora composition along various aspects of the upper gastrointestinal tract in patients with Barrett's esophagus.

Methods

After obtaining institutional review board approval, 12 patients agreed to participate in the study. While endoscopy was performed for surveillance Barrett's monitoring, additional biopsies of esophageal mucosa were taken from the (I) proximal esophagus, (II) mid-esophagus, (III) distal esophagus, and (IV) Barrett's esophagus. Additional swabs were also taken from the uvula and the endoscope used during the procedure. The swabs from the uvula and endoscope were obtained prior to the endoscope entering the stomach, to prevent exposing the endoscope to the acidic environment of the stomach. The most common bacterial elements were identified by amplifying sample DNA using a panel of 5 "universal" fusion primer pairs. The 400-500 base pair fragments created an overlap which covered 95% of the bacterial 16s gene.

Results

Throughout the esophagus, 34 bacterial genera were found which had a relative abundance of >1.0. Streptococcal genera were prevalent in all aspects of the esophagus, ranging from 16% to 70% of the bacterial community. Haemophilus genera were uniquely abundant in the Barrett's esophageal tissue but relatively absent elsewhere in the upper gastrointestinal tract. Overall, the percentage of Gram-positive organisms was much higher in the proximal than distal esophagus. The microflora pattern obtained from the uvula and endoscopic swabs did not correlate with any of the tissue biopsies along any aspect of the esophagus.

Conclusions

In patients with Barrett's esophagus, Streptococcal genera are widespread throughout the esophagus. Gram-positive genera tend to decrease as a percentage of overall flora distally. Obtaining a simple swab of the oropharynx or endoscope itself appears to be a poor substitute for tissue biopsy of esophageal mucosa when evaluating microflora patterns.

Systematic review with meta-analysis: prevalent vs. incident oesophageal adenocarcinoma and high-grade dysplasia in Barrett's oesophagus

BACKGROUND

The proportion of oesophageal adenocarcinoma that is detected concurrently with initial Barrett's oesophagus diagnosis is not well studied.

AIM

To compare the proportion of prevalent adenocarcinoma vs. incident adenocarcinoma found during surveillance of Barrett's.

METHODS

We performed a systematic search of MEDLINE, EMBASE and Web of Science (from their inception to 31 May 2015) for cohort studies in adults with Barrett's (nondysplastic Barrett's ± Barrett's with low-grade dysplasia) with minimum average follow-up of 3 years, and providing numbers of prevalent adenocarcinoma detected (concurrently with Barrett's diagnosis and up to 1 year afterwards) vs. incident adenocarcinoma detected (greater than 1 year after Barrett's diagnosis). Pooled weighted proportions of prevalent and incident adenocarcinoma were calculated, using a random effects model.

RESULTS

On meta-analysis of 13 studies reporting on 603 adenocarcinomas in 9657 Barrett's patients, 85.1% of adenocarcinomas were classified as prevalent [95% confidence interval (CI), 78.1-90.2%) and 14.9% as incident (95% CI, 9.8-21.9%), with substantial heterogeneity (I(2) = 66%). Among nine studies reporting on 787 high-grade dysplasia and oesophageal adenocarcinomas in 8098 Barrett's patients, the proportion of prevalent high-grade dysplasia-oesophageal adenocarcinoma was similar at 80.5% (95% CI, 68.1-88.8%, I(2) = 87%). These results remained stable across multiple subgroup analyses including study quality, setting, duration of follow-up and presence of baseline dysplasia.

CONCLUSIONS

In our meta-analysis, four of five patients diagnosed with adenocarcinoma or high-grade dysplasia at index endoscopy or within 1 year of Barrett's follow-up were considered to be prevalent cases. Continued efforts are needed to identify patients with Barrett's before the development of adenocarcinoma.