Cohort Study for Gastric MALT Lymphoma

This cohort study follows patients with gastric MALT lymphoma — a slow-growing type of stomach cancer linked to H. pylori bacterial infection — to understand how the disease behaves over time and what factors predict outcomes. A control group of patients with routine stomach issues is also included. **You may be eligible if...** - You have been newly diagnosed with gastric MALT lymphoma (patient group) - OR you are undergoing upper endoscopy (stomach scope) for dyspepsia, gastric polyps, or routine screening with no cancer history (control group) **You may NOT be eligible if...** - You have a history of stomach cancer or another malignancy - You have taken antibiotics or probiotics in the past 4 weeks - You have serious uncontrolled chronic illnesses Talk to your doctor to see if this trial is right for you.