## Gastric Adenocarcinoma — Site Distribution **Key Point:** The pyloric antrum (distal third) is the most common site of origin for gastric adenocarcinoma, accounting for approximately 50–60% of cases. This is followed by the body (25–30%) and cardia (10–15%). **High-Yield:** Intestinal-type adenocarcinoma (the most common histological variant in India) preferentially arises in the distal stomach due to chronic gastritis and intestinal metaplasia from *Helicobacter pylori* infection, which is endemic in the Indian subcontinent. **Clinical Pearl:** The pyloric antrum has the highest concentration of gastrin-secreting G cells and is exposed to the most acidic chyme; chronic inflammation in this region predisposes to malignant transformation. ### Histological Features of Gastric Adenocarcinoma | Feature | Intestinal Type | Diffuse Type | |---------|-----------------|---------------| | **Site** | Distal stomach (antrum) | Diffuse throughout stomach | | **Appearance** | Glandular structures, mucin-producing | Signet-ring cells, poorly cohesive | | **Prognosis** | Better (early detection possible) | Worse (advanced at diagnosis) | | **Association** | *H. pylori*, intestinal metaplasia | Hereditary diffuse gastric cancer (CDH1 mutation) | **Mnemonic:** **ACID** — **A**ntrum is **C**ommon site, **I**ntestinal type, **D**istal location.
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