Targeting the Helicobacter pylori–Gastric Cancer Axis with Nanomaterials: From Infection Control to Tumor-Directed Therapy

Helicobacter pylori (H. pylori) infection promotes persistent mucosal inflammation, oxidative stress, epithelial injury, immune dysregulation, and progressive remodeling of the gastric microenvironment, thereby increasing the risk of gastric cancer (GC). Although H. pylori eradication and GC therapy are usually treated as separate clinical problems, they are linked by a continuum of pathogenic processes. Nanomaterial-based therapeutic systems may help overcome different barriers on this axis by improving drug stability and delivery, facilitating transport through mucus and biofilms, and enabling host-directed immunomodulation. This review focuses on polymeric, lipid-based, inorganic, hybrid, and stimuli-responsive approaches relevant to the management of H. pylori infection and the treatment of GC, emphasizing how carrier design can be adapted to different disease stages. Selected chitosan-based particles and functionalized poly(lactic acid) systems are discussed as examples of stage-adapted delivery strategies across the infection–cancer continuum. This review also describes three-dimensional and infection-associated GC models as tools for assessing nanoparticle penetration and therapeutic responses under more physiologically relevant conditions. Stage-adapted interventions are considered as distinct or potentially sequential approaches, rather than as a single validated platform combining bacterial eradication, inflammation control, mucosal repair, and anticancer therapy.