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.
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.
Problem statement Barrett's oesophagus is a pre-cancerous condition affecting 375,000 people in the U.K. There is a 0.5-3% yearly risk of progressing to oesophageal cancer, from which only 5% of patients will survive for 5 years after diagnosis. Diagnosing the disease at the stage of dysplasia (pre-cancerous) and early cancer improves survival. This has led to the current surveillance strategy of gastroscopy with non-targeted mapping biopsies taken from the Barrett's oesophagus every two years. The large number of biopsies required is time consuming and expensive, yet dysplasia and cancerous tissue is still missed due to the non-targeted biopsy sampling strategy. Acetic acid has been used effectively in the early detection of cervical dysplasia and cancer, and has also been used with success in a high risk Barrett's population (patients with suspected dysplasia or previously treated dysplasia), but not been studied in the lower risk Barrett's surveillance population. A diagnostic study of non-targeted mapping biopsies (current practice) versus targeted biopsies (acetic acid) in a surveillance population is needed before widespread adoption of this technique is possible.
This is a feasibility study to enable powering of a larger study. The investigators would assume a disease detection of 4.5% with acetic acid chromoendoscopy and 1.5% with protocol driven mapping biopsies. However, these assumptions are largely driven from a single centre cohort study and as such need clarification before they could be used for the purposes of powering a study. Based on the historical cohort studies and wide consultation within the British Society of Gastroenterology research committee and consultation with experts in the field, it is estimated that 200 patients would be reasonable for recruitment to enable the reproducibility and generalisability of this data to be established. The purpose of this study is not to produce statistically significant data in itself but to establish likely event rates and effect size to inform the power calculation for the definitive study.
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