Patho: If left untreated, H. pylori infection initiates a slow carcinogenic process, developing over decades and eventually leading to antral-predominant chronic active gastritis and ultimately to multifocal atrophic gastritis, which is a risk factor for intestinal and, less commonly, diffuse gastric adenocarcinomas (Lauwers & Kumarasinghe, 2022). While H. pylori infection usually starts in infancy or early childhood, there is a long latency period, and cancers are clinically diagnosed four or more decades later (Lauwers & Kumarasinghe, 2022). During this period, a prolonged precancerous process takes place, represented by a "cascade" of sequential histopathologic stages: chronic active nonatrophic gastritis, multifocal atrophic gastritis, intestinal metaplasia (complete, then incomplete), dysplasia, and invasive carcinoma in a high-incidence area (Lauwers & Kumarasinghe, 2022).
