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Esophageal Cancer for the USMLE Step 1 Exam

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Esophageal Cancer for USMLE Step 1
Definition
  • Esophageal Cancer: Malignancy of the esophagus, classified into two main types:
    • Squamous Cell Carcinoma (SCC): Arises from squamous cells lining the esophagus, more common worldwide.
    • Adenocarcinoma: Arises from columnar epithelium, typically from Barrett’s esophagus, and is more common in Western countries.
Epidemiology
  • Squamous Cell Carcinoma:
    • Predominant in developing countries, particularly in Asia and parts of Africa.
    • Primarily affects the middle and upper esophagus.
  • Adenocarcinoma:
    • Common in developed countries, such as the United States.
    • Frequently arises in the distal esophagus, linked to Barrett’s esophagus.
Risk Factors
  • Squamous Cell Carcinoma:
    • Smoking and alcohol use: Major risk factors.
    • Diet: Low intake of fruits and vegetables; consumption of hot beverages.
    • Achalasia and previous esophageal injury (e.g., lye ingestion).
  • Adenocarcinoma:
    • GERD and Barrett’s Esophagus: Chronic gastroesophageal reflux is the most significant risk factor.
    • Obesity: Increases intra-abdominal pressure, promoting GERD.
    • Smoking: Contributes to the risk of adenocarcinoma.
Pathophysiology
  • Squamous Cell Carcinoma:
    • Chronic irritation (e.g., smoking, alcohol) causes dysplasia of the squamous epithelium, progressing to carcinoma.
    • Typically affects the middle and upper esophagus.
  • Adenocarcinoma:
    • Arises from Barrett’s esophagus, a condition where chronic acid exposure from GERD causes metaplasia of the squamous epithelium into columnar epithelium with goblet cells.
    • Progresses from metaplasia to dysplasia and finally to adenocarcinoma.
    • Commonly found in the distal esophagus near the gastroesophageal junction.
Clinical Features
  • Dysphagia: The most common symptom, typically starting with difficulty swallowing solids and progressing to liquids as the tumor obstructs the esophageal lumen.
  • Weight Loss: Unintentional and significant due to decreased oral intake and cancer cachexia.
  • Odynophagia: Painful swallowing, often due to tumor ulceration.
  • Chest Pain: Non-specific retrosternal discomfort or pain.
  • Hoarseness: Indicates possible involvement of the recurrent laryngeal nerve in advanced disease.
  • GI Bleeding: May present as hematemesis or melena from tumor ulceration.
Esophageal Cancer - dysphagia
Diagnosis
  • Endoscopy with Biopsy:
    • Esophagogastroduodenoscopy (EGD): Gold standard for diagnosing esophageal cancer. Provides visualization and biopsy of suspicious lesions.
    • Histological examination confirms squamous cell carcinoma or adenocarcinoma.
  • Barium Swallow:
    • May show a characteristic apple-core lesion or stricture, indicating a mass causing esophageal narrowing.
  • Imaging:
    • CT or PET/CT scans: Used for staging to assess local invasion and distant metastasis (commonly to the liver, lungs, and lymph nodes).
Staging
  • TNM Classification:
    • T (Tumor): Describes the depth of invasion of the esophageal wall and surrounding structures.
    • N (Nodes): Describes regional lymph node involvement.
    • M (Metastasis): Identifies the presence of distant metastasis.
Treatment
  • Surgical Resection:
    • Esophagectomy: The mainstay of treatment for localized disease. May involve removing part or all of the esophagus.
  • Endoscopic Mucosal Resection (EMR):
    • Indicated for early-stage disease (Tis or T1a) confined to the mucosa.
  • Neoadjuvant Chemoradiotherapy:
    • Preoperative chemoradiation is often used for locally advanced disease (T2 or higher) to shrink the tumor and improve surgical outcomes.
  • Palliative Therapy:
    • For advanced-stage or metastatic disease, palliative care focuses on symptom relief.
    • Esophageal stenting: Used to relieve dysphagia in inoperable cases.
Complications
  • Local Invasion: Tumors can invade surrounding structures, such as the trachea, leading to fistula formation (e.g., tracheoesophageal fistula).
  • Metastasis: Commonly spreads to regional lymph nodes, liver, lungs, and adrenal glands.
  • Malnutrition: Due to dysphagia and decreased intake.
Prevention
  • Tobacco and Alcohol Cessation: Reduces the risk of squamous cell carcinoma.
  • Management of GERD: Early treatment of GERD and surveillance for Barrett’s esophagus can prevent progression to adenocarcinoma.
  • Diet: A diet rich in fruits and vegetables may lower the risk of both types of esophageal cancer.
Key Points
  • Esophageal cancer is classified into squamous cell carcinoma (upper/mid esophagus) and adenocarcinoma (distal esophagus), with different risk factors.
  • Major risk factors for SCC include smoking, alcohol use, and hot beverages, while GERD and Barrett’s esophagus are key contributors to adenocarcinoma.
  • Symptoms include progressive dysphagia, weight loss, and chest pain, with endoscopy being the gold standard for diagnosis.
  • Treatment depends on the stage, with surgery (esophagectomy) for localized disease, chemoradiotherapy for advanced disease, and palliative care for metastatic cases.
  • Early detection and management of GERD and Barrett’s esophagus can reduce the risk of adenocarcinoma.

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