http://youtu.be/YDhBRu7nUh8 Etiology Helicobacter pylori infection is the cause of most stomach cancer. Autoimmune atrophic gastritis and various genetic factors: Gastrointestinal Stromal Tumors are also risk factors. Dietary factors are not proven causes. Gastric polyps can be precursors of cancer. Inflammatory polyps may develop in patients taking NSAIDs, and fundic foveolar polyps are common among patients taking proton pump inhibitors. Adenomatous polyps, particularly multiple ones, although rare, are the most likely to develop cancer. Cancer is particularly likely if an adenomatous polyp is 2 cm in diameter or has a villous histology. Because malignant transformation cannot be detected by inspection, all polyps seen at endoscopy should be removed. The incidence of stomach cancer is generally decreased in patients with duodenal ulcer. Pathophysiology Gastric adenocarcinomas can be classified by gross appearance: Protruding: The tumor is polypoid or fungating. Penetrating: The tumor is ulcerated. Superficial spreading: The tumor spreads along the mucosa or infiltrates superficially within the wall of the stomach. Linitis plastica: The tumor infiltrates the stomach wall with an associated fibrous reaction that causes a rigid leather bottle stomach. Miscellaneous: The tumor shows characteristics of 2 of the other types; this classification is the largest. Prognosis is better with protruding tumors than with spreading tumors because protruding tumors become symptomatic earlier.