Gastric Cancer

Jun 19, 2024

Gastric Cancer Lecture Notes

Overview

  • Definition: Malignant or cancerous cells in the stomach.
  • Types: Classified based on originating cells:
    • Adenocarcinoma: Columnar glandular epithelium
    • Lymphoma: Lymphocytes
    • Carcinoid tumor: G cells
    • Lyomyosarcoma: Smooth muscle cells

Stomach Anatomy

  • Regions: Cardia, Fundus, Body, Pyloric Antrum
  • Layers: Four layers of gastric wall:
    1. Adventitia (serosa)
    2. Muscular layer
    3. Submucosa
    4. Mucosa
  • Mucosa: Three layers
    1. Epithelial layer: Secretes mucus and digestive enzymes
    2. Lamina propria: Contains blood, lymph vessels, and MALT
    3. Muscularis mucosa: Smooth muscle aiding food breakdown
  • Gastric Pits and Glands: Different epithelial cells secrete various substances (e.g., surface mucus cells, parietal cells, chief cells, G cells)

Types of Gastric Cancer

  • Adenocarcinoma: Most common; 2 subtypes:
    • Intestinal (well-differentiated): Often related to H. pylori
      • H. pylori causes chronic gastritis, metaplasia, and mutagenesis
      • Tumor appears on lesser curvature of the antrum
    • Diffuse (undifferentiated): Related to CDH1 gene mutations
      • E-cadherin malfunction leads to cell detachment and uncontrolled division
      • More aggressive, can cause linitis plastica
  • Other Types:
    • Lymphoma: Excessive B-cell proliferation due to chronic H. pylori infection
    • Carcinoid Tumor: From G cells, appears as a polyp
    • Lyomyosarcoma: From smooth muscle cells, very rare

Complications

  • Metastasis: Spread to peritoneum, lymph nodes, liver; specific metastases:
    • Kruckenberg Tumor: Bilateral ovarian metastases
  • Perineoplastic Syndromes:
    • Leser-Trelat sign: Seborrheic keratosis spots
    • Polyarteritis Nodosa: Inflammation and necrosis of arteries
    • Trousseau Syndrome: Migratory thrombosis in veins

Risk Factors

  • General: Family history, smoking, alcohol, obesity, increasing age
  • Specific (intestinal adenocarcinoma): Male, H. pylori, blood type A, diet high in nitrates and nitrosamines, autoimmune conditions
  • Protective: High intake of fruits, vegetables, fiber, and folate

Symptoms

  • Early: Asymptomatic or vague symptoms like malaise, loss of appetite, dyspepsia
  • Advanced: Epigastric pain, nausea, vomiting, weight loss, possible anemia, hematemesis, melena
  • Perineoplastic Signs: Leser-Trelat sign, polyarteritis nodosa, Trousseau syndrome, acanthosis nigricans, Sister Mary Joseph sign

Diagnosis

  • Endoscopy: Direct tumor visualization and biopsy
  • X-rays with Barium: To identify complications
  • Abdominopelvic CT: To assess spread to other organs/lymph nodes

Treatment

  • Early Stage: Surgery
  • Advanced Stage: Palliative surgery, chemo, radiotherapy

Recap

  • Gastric Cancer: Malignant cells in stomach, most commonly adenocarcinoma
  • Complications: Metastasis, perineoplastic syndromes
  • Risk Factors: Family history, smoking, alcohol, obesity, H. pylori
  • Protective Factors: Fruits, vegetables, fiber, folate
  • Symptoms: Early asymptomatic, advanced include pain and weight loss
  • Diagnosis: Endoscopy and biopsy, X-rays, CT
  • Treatment: Surgery, with chemo and radiotherapy for advanced cases