Gastric Cancer

Snapshot

A 56-year-old man presents to his primary care physician for abdominal pain. His abdominal pain is in the epigastrium and has been persistent. He has had episodes of night sweats and has unintentionally lost 20 pounds over the course of 3 months. He has a past medical history of H. pylori infection and obesity. Physical examination is notable for epigastric abdominal tenderness upon palpation. An upper endoscopy demonstrates an invasive ulcerative lesion in the stomach.

Introduction

Overview
- gastric adenocarcinoma is the most common type of gastric cancer, accounting for more than 90% of cases
  - other gastric cancer types include lymphoma, stromal, and carcinoid tumor
- gastric adenocarcinoma can be divided into intestinal and diffuse types
  - intestinal
    - bulky tumors that have glandular structures (similar to adenocarcinoma of the esophagus and colon)
      - the mass can be exophytic or ulcerated
    - commonly found on the lesser curvature of the stomach
  - diffuse
    - infiltrative tumors composed of signet ring cells (mucin vacuoles that push the nucleus to the periphery)
    - stiffens the gastric wall, leading to a thickened, leather-like appearance (linitis plastica)
Epidemiology
- incidence
  - varies significantly in the world
    - most common in Japan, Chile, and eastern Europe
- risk factors
  - Helicobacter pylori
  - Epstein-Barr virus
  - nitrosamine exposure
  - high salt intake
  - smoking
  - excessive alcohol use
Pathophysiology
- H. pylori infection
  - results in chronic gastritis secondary to increased production of proinflammator proteins
- Epstein-Barr virus
  - a rare cause of gastric adenocarcinoma
unclear how exactly this virus leads to gastric adenocarcinoma

Presentation

Symptoms
- persistent abdominal pain
  - typically epigastric
- dysphagia
  - in cases of gastric cancers arising more proximally in the stomach or in the esophagogastric junction
Physical examination
- weight loss
secondary to insuficcient caloric intake

Imaging

Endoscopy
- indication
  - initial diagnostic study of choice to obtain a tissue diagnosis
Barium studies
- indication
although associated with a high false-negative rate, it may be superior to endoscopy in detecting linitis plastica

Differential

Gastric lymphoma
- differentiating factors
  - secondary to B-cell lymphoproliferative disorders
  - associated with mucosa-associated lymphoid tissue
Gastric stromal cancer
- differentiating factors
  - mesechymal in origin
Neuroendocrine (carcinoid) tumor
- differentiating factors
  - arise from neuroendocrine origin
  - leads to release of vasoactive substances, resulting in cutaneous flushing, bronchospasm, colicky abdominal pain, and diarrhea
as well as right-sided cardiac valvular fiborosis

Treatment

Treatment is dependent on the stage of the cancer
- may require resection, adjuvant chemotherapy, and radiation
Surgical
- endoscopic resection
  - indication
    - for local tumors
- gastrectomy with lymphadenectomy
  - indication
for more extensive disease

Complications