What this Trial Is About

Gastric cancer remains a global health problem, and Chile has one of the highest GC mortality rates in the region. Helicobacter pylori (H. pylori) infection is ubiquitous in Chilean adults, and it constitutes the main cause of GC worldwide. A long-term process occurs from premalignant lesions to carcinoma. H. pylori eradication during early stages of disease significantly impacts outcomes, favoring survival, disease reversal and molecular changes, which supports a "screen and treat" strategy in asymptomatic populations in areas with intermediate-to-high GC prevalence. The Investigators' previous research has shown that H. pylori infection is acquired in early childhood with low rates of spontaneous eradication. A pilot treatment study in a subset of school-aged asymptomatic children showed a high rate of successful eradication (\>95%), good tolerance, and was associated with a decrease in serum biomarkers of gastric damage (pepsinogen I and II). Based on the results of these studies, the Investigators propose to advance towards the next stage of this research process: a "screen and treat" strategy. The current trial starts with a Screening phase testing up to 1000 asymptomatic adolescents 14-18 years of age from 3 cities of Chile (Colina, Temuco and Coyhaique), to find a total of 210 persistently-infected participants. Persistently-infected adolescents will be included in a Second phase of this trial: A randomized, case-control, non-blinded study to either receive antimicrobial treatment targeting H. pylori eradication (cases) or no treatment (controls). A subset of 60 non-infected adolescents will be followed-up in matched times. This aims to provide evidence on the effect of treatment on clinical outcomes and serum biomarkers related to gastric damage, as well as composition and antimicrobial resistance of gut microbiota. The Investigators expect that eradication therapy will be successful in \>90% of persistently infected adolescents, with reinfection rates not surpassing 15% in a 2-3 year period, and to be associated with a decrease in clinical findings indicative of gastric disease, and a decrease in serum biomarker indicative of "gastric damage".

A "Screen and Treat" Helicobacter Pylori Eradication Trial in Adolescents in Three Regions of Chile