Acetic acid guided biopsies in Barrett’s surveillance for neoplasia detection versus non-targeted biopsies (Seattle protocol): a feasibility study for a randomised tandem endoscopy trial. The ABBA study.

Background and study aims - Barrett’s esophagus is a potentially pre-cancerous condition, affecting 375,000 people in the UK. Patients receive a 2-yearly endoscopy to detect cancerous changes, as early detection and treatment results in better outcomes. Current treatment requires random mapping biopsies along the length of Barrett’s, in addition to biopsy of visible abnormalities. As only 13 % of precancerous changes appear as visible nodules or abnormalities, areas of dysplasia are often missed. Acetic acid chromoendoscopy (AAC) has been shown to improve detection of pre-cancerous and cancerous tissue in observational studies, but no randomized controlled trials (RCTs) have been performed to date. 

Patients and methods - A “tandem” endoscopy cross-overdesign. Participants will be randomized to endoscopy usingmapping biopsies or AAC, in which dilute acetic acid issprayed onto the surface of the esophagus, highlighting tissuethrough an whitening reaction and enhancing visibilityof areas with cellular changes for biopsy. After 4 to 10weeks, participants will undergo a repeat endoscopy, usingthe second method. Rates of recruitment and retention willbe assessed, in addition to the estimated dysplasia detectionrate, effectiveness of the endoscopist training program,and rates of adverse events (AEs). Qualitative interviewswill explore participant and endoscopist acceptabilityof study design and delivery, and the acceptability ofswitching endoscopic techniques for Barrett's surveillance. 

Results - Endoscopists’ ability to diagnose dysplasia in Barrett’sesophagus can be improved. AAC may offer a simple,universally applicable, easily-acquired technique to improvedetection, affording patients earlier diagnosis and treatment,reducing endoscopy time and pathology costs. TheABBA study will determine whether a crossover “tandem”endoscopy design is feasible and acceptable to patientsand clinicians and gather outcome data to power a definitivetrial.