Introduction The identification of Barrett's neoplasia using acetic acid has relied upon the examination of surface patterns, which involves subjective judgement. When sprayed onto Barrett's tissue acetic acid causes an acetowhitening reaction. We have observed that neoplastic tissue loses this whitening more quickly than non-neoplastic Barrett's. This study aims to quantify the acetowhitening time and develop an objective tool for the diagnosis of Barrett's neoplasia.
Methods Patients referred for suspected Barrett's neoplasia and for routine Barrett's surveillance were assessed. A 50 ml mucolytic drink of 10% N-acetyl cysteine and 5 ml of simethicone was taken prior to the procedure. Fujinon gastroscopes with EPX 4400 processor were used. 20 ml of 2.5% acetic acid was applied to the Barrett's mucosa via a spray catheter. Timing was recorded with a stopwatch and started after the oesophagus had been coated with acetic acid and the excess dye sucked away. Disappearance of the acetowhitening was defined as the appearance of erythema within the Barrett's epithelium. After a maximum of 5 min the Barrett's epithelium was washed using 20 ml of water and targeted biopsies of any neoplasia and quadrantic 2 cm biopsies of the residual Barrett's was taken. The histology was correlated to the acetowhitening disappearance time. ROC curves were produced to identify threshold timings for optimum sensitivity and specificity for high risk neoplasia and invasive cancer within Barrett's.
Results Data from 146 areas of Barrett's was collected from 121 patients. 84% were male. Mean age 69. 72/86 metaplasia, 6/14 LGD, 26/27 HGD, 15/15 IMC and 12/12 areas of invasive cancer were recognised correctly by the endoscopist. A ROC curve was produced for the identification of high risk neoplasia (HGD, IMC and invasive cancer) using the acetowhitening timings. The area under the curve was 0.93 (95% CI 0.89 to 0.97), with an asymptomatic significance of p=0.000. Using a threshold of 142 s a sensitivity for neoplasia of 98% (95% CI 89% to 100%) and specificity of 84% (95% CI 74% to 91%) was achieved. A further ROC curve was produced for HGD + IMC vs invasive cancer. The area under the curve was 0.786 (61 to 96). Using a cut off of 20 s, a sensitivity for invasive cancer of 67% (95% CI 35% to 90%) and specificity of 85% (95% CI 69% to 95%) could be achieved.
Conclusion The acetowhitening reaction can be exploited for the diagnosis of neoplasia within Barrett's. This provides the endoscopist with an objective and simple numerical tool for predicting whether an area is neoplastic, and to predict the presence of sub-mucosally invasive disease. This has important implications for the treatment of neoplasia within Barrett's, and could prevent inappropriate attempts at endoscopic resection of invasive cancer.
Competing interests None declared.
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