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Esophageal Cancer for the USMLE Step 2 Exam

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Esophageal Cancer for USMLE Step 2
Definition
  • Esophageal Cancer: A malignancy originating in the esophagus, divided into two major types:
    • Squamous Cell Carcinoma (SCC): Arises from the squamous epithelium of the esophagus, more common worldwide.
    • Adenocarcinoma: Arises from metaplastic columnar epithelium in Barrett’s esophagus, more common in Western countries.
Epidemiology
  • Squamous Cell Carcinoma:
    • More common in Asia and parts of Africa, typically affecting the upper and middle thirds of the esophagus.
  • Adenocarcinoma:
    • More prevalent in the U.S. and Western countries.
    • Primarily affects the distal esophagus, near the gastroesophageal junction, and is strongly linked to GERD and Barrett’s esophagus.
Risk Factors
  • Squamous Cell Carcinoma:
    • Tobacco and alcohol use: The two most significant risk factors.
    • Hot beverages: Chronic irritation from hot liquids.
    • Achalasia: Increased risk due to prolonged food stasis and irritation.
    • Diet: Low intake of fruits and vegetables.
  • Adenocarcinoma:
    • GERD: Chronic gastroesophageal reflux leads to Barrett’s esophagus, a precursor to adenocarcinoma.
    • Barrett’s Esophagus: The primary risk factor for adenocarcinoma.
    • Obesity: Increases the risk by promoting reflux.
    • Smoking: Also contributes to the risk of adenocarcinoma.
Pathophysiology
  • Squamous Cell Carcinoma:
    • Chronic irritation (e.g., smoking, alcohol) causes dysplasia in the squamous cells, leading to carcinoma.
    • Typically arises in the middle or upper esophagus.
  • Adenocarcinoma:
    • Arises from Barrett’s esophagus, where chronic acid reflux causes metaplasia of the esophageal squamous epithelium into columnar epithelium with goblet cells (intestinal metaplasia).
    • Found primarily in the distal esophagus.
Clinical Features
  • Dysphagia: The most common symptom, beginning with difficulty swallowing solids and progressing to liquids as the tumor obstructs the esophagus.
  • Weight Loss: Significant, due to difficulty eating and cancer-associated cachexia.
  • Odynophagia: Painful swallowing, often indicating advanced disease.
  • Chest Pain: Non-specific discomfort or pain behind the sternum.
  • Hoarseness: Suggests involvement of the recurrent laryngeal nerve in advanced disease.
  • GI Bleeding: Hematemesis or melena may occur from tumor ulceration.
Esophageal Cancer - dysphagia
Diagnosis
  • Endoscopy with Biopsy:
    • Esophagogastroduodenoscopy (EGD): The gold standard for diagnosis. It provides direct visualization of the tumor and allows for biopsy to confirm squamous cell carcinoma or adenocarcinoma.
  • Barium Swallow:
    • May reveal a stricture or apple-core lesion, indicative of an obstructive tumor.
  • CT Scan or PET/CT:
    • Used for staging to evaluate the extent of local invasion and distant metastasis (commonly to the liver, lungs, and lymph nodes).
Staging
  • TNM Classification:
    • T (Tumor): Describes how deeply the tumor has invaded the esophageal wall.
    • N (Nodes): Indicates regional lymph node involvement.
    • M (Metastasis): Indicates distant metastasis to organs such as the liver or lungs.
Treatment
  • Surgical Resection:
    • Esophagectomy: The main treatment for localized disease. It involves removing part or all of the esophagus and reconstructing it.
    • Endoscopic Mucosal Resection (EMR): Used for very early-stage tumors (T1a) confined to the mucosa.
  • Neoadjuvant Chemoradiotherapy:
    • Preoperative chemoradiation is the standard for locally advanced tumors (T2 or higher) to shrink the tumor and improve surgical outcomes.
  • Palliative Therapy:
    • For advanced-stage or inoperable tumors, treatment focuses on relieving symptoms such as dysphagia and pain.
    • Esophageal stenting: Used to alleviate obstruction and improve swallowing.
    • Palliative Chemoradiotherapy: May be used to control symptoms and slow progression in metastatic disease.
Complications
  • Local Invasion: Tumors may invade nearby structures, such as the trachea, leading to tracheoesophageal fistulas.
  • Distant Metastasis: Commonly spreads to the liver, lungs, and regional lymph nodes.
  • Malnutrition: Resulting from dysphagia and reduced oral intake.
Prevention
  • Tobacco and Alcohol Cessation: Decreases the risk of squamous cell carcinoma.
  • GERD Management: Treating chronic reflux and monitoring for Barrett’s esophagus reduces the risk of adenocarcinoma.
  • Diet: A diet rich in fruits and vegetables may lower the risk of esophageal cancer.
Key Points
  • Esophageal cancer is classified into squamous cell carcinoma (common globally) and adenocarcinoma (common in Western countries, associated with GERD and Barrett’s esophagus).
  • Major risk factors for SCC include smoking, alcohol, and hot beverages, while GERD and Barrett’s esophagus are major contributors to adenocarcinoma.
  • Symptoms include dysphagia, weight loss, chest pain, and GI bleeding. Diagnosis is confirmed with endoscopy and biopsy.
  • Treatment for localized disease includes esophagectomy, while neoadjuvant chemoradiation is used for locally advanced tumors. Palliative care focuses on symptom relief in metastatic cases.
  • Prevention focuses on lifestyle modifications, including smoking cessation, alcohol avoidance, and managing GERD to prevent Barrett’s esophagus.

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