Abstract
Background and study aims White opaque substance (WOS) in gastric epithelial neoplasia is helpful for qualitative
diagnosis of neoplasia. We hypothesized that WOS of neoplasia is strongly influenced
by acid recovery after Helicobacter pylori eradication, similar to that of gastric intestinal metaplasia. The aim of this study
was to investigate whether antacids increase the appearance of the WOS in H. pylori-eradicated neoplasia.
Patients and methods A total of 38 gastric epithelial neoplasias (12 adenomas and 26 adenocarcinomas)
detected after H. pylori eradication were retrospectively evaluated. Presence or absence of WOS was evaluated
by magnifying endoscopy with narrow band imaging before and after antacid administration.
The pH of collected gastric juice was also measured. Study endpoints were (1) prevalence
of WOS in the neoplasia before and after antacid administration, and the histological
difference (adenoma and adenocarcinoma); and (2) relationship between the prevalence
of WOS and gastric juice pH.
Results WOS prevalence increased from 0 % (0/38) to 44.8% (17/38) after antacid administration.
WOS prevalence in adenomas was more significantly increased compared to that in adenocarcinomas
(83.3 % vs 26.9 %, P = 0.0077). Prevalence of WOS in gastric neoplasias was only observed at neutral levels
of gastric juice pH, and WOS was not observed at strong acidic levels.
Conclusions Antacid administration may increase the appearance of WOS in gastric epithelial neoplasia
(especially adenomas) detected after H. pylori eradication with acid recovery.