A 62-year-old obese white man presents with progressive dysphagia to solids over 8 months and weight loss of 6 kg. Upper endoscopy reveals a fungating, ulcerated mass within salmon-pink columnar mucosa in the distal esophagus extending from the gastroesophageal junction, as marked **A** in the diagram. Biopsies confirm adenocarcinoma with intestinal metaplasia and goblet cells in the surrounding mucosa. Which of the following best describes the pathogenic sequence that led to the lesion marked **A**?

Explanation

## Why "Chronic GERD → Barrett esophagus (intestinal metaplasia) → dysplasia → adenocarcinoma" is right The lesion marked **A** is esophageal adenocarcinoma (EAC) at the GEJ arising in a Barrett background (salmon-pink columnar mucosa with goblet cells on histology). This represents the final stage of the well-established GERD → BARRETT → DYSPLASIA → ADENOCARCINOMA sequence. Chronic acid and bile reflux injures the distal esophageal squamous epithelium, which heals by metaplasia to intestinal-type columnar epithelium containing goblet cells (Barrett esophagus). Persistent inflammation and oxidative stress drive accumulation of genetic abnormalities (TP53 loss, CDKN2A loss, aneuploidy) progressing through low-grade dysplasia, high-grade dysplasia, intramucosal carcinoma, and finally invasive adenocarcinoma. The patient's risk factors (age 62, male, white, obesity, 8-year GERD history) are classic for EAC. This is the pathogenic mechanism described in Sleisenger & Fordtran 11e Ch 46. ## Why each distractor is wrong - **Chronic smoking and alcohol use → squamous dysplasia → squamous cell carcinoma**: This is the pathogenic sequence for esophageal squamous cell carcinoma (SCC), which typically arises in the mid-esophagus and is associated with smoking and alcohol. The lesion marked **A** is adenocarcinoma in a Barrett background (distal esophagus), not SCC. - **Caustic ingestion → esophageal stricture → secondary malignancy**: While caustic injury can cause strictures and increase cancer risk, it is not the primary mechanism for the common presentation of EAC. The lesion marked **A** shows no history of caustic exposure and arises in Barrett mucosa, not post-caustic stricture. - **H. pylori infection → chronic atrophic gastritis → intestinal metaplasia of stomach → esophageal adenocarcinoma**: H. pylori infection is actually a protective factor against EAC because atrophic gastritis reduces gastric acid production, thereby reducing reflux. H. pylori does not cause esophageal adenocarcinoma; it causes gastric cancer. The intestinal metaplasia in **A** is esophageal (Barrett), not gastric. **High-Yield:** EAC arises almost exclusively in Barrett esophagus via the GERD → metaplasia → dysplasia → cancer sequence; smoking/alcohol cause SCC (mid-esophagus), not adenocarcinoma (distal esophagus). [cite:Sleisenger & Fordtran 11e Ch 46; CROSS trial NEJM 2012; CheckMate 577 NEJM 2021]