2. Gastric Cancer

 

 Gastric Cancer

1. Epidemiology and Incidence

  • Global Distribution:
    • High Incidence: Eastern Asia (Japan, South Korea, China), Andean regions of South America, and Eastern Europe.
    • Low Incidence: North America, Northern Europe, Africa, Southeast Asia (including India).
  • UK Regional Trends:
    • Higher incidence in Northern regions compared to Southern regions.
  • Demographics:
    • Peak age: 50–60 years.
    • Male-to-female ratio: 2–12:1.
  • Trends:
    • Decline in distal (non-cardia) gastric cancers.
    • Increase in proximal (cardia) gastric cancers.

2. Pathophysiology and Risk Factors

  • Carcinogenesis:
    • Chronic inflammation leading to intestinal metaplasia and dysplasia.
    • Key pathways: Helicobacter pylori infection, genetic mutations (e.g., CDH1 for hereditary diffuse gastric cancer).
  • Key Risk Factors:
    • H. pylori infection (most important risk factor).
    • High-salt diet, processed meats, cured fish.
    • Smoking and obesity.
    • Prior gastric surgery (e.g., Billroth II).
    • Genetic predisposition: hereditary conditions (FAP, Lynch syndrome).
  • Protective Factors:
    • Diet rich in fruits and vegetables.
    • Use of NSAIDs (may reduce risk).

3. Clinical Presentation

  • Symptoms of Early-Stage Disease: Often asymptomatic.
  • Symptoms of Advanced-Stage Disease:
    • Weight loss, epigastric pain, early satiety.
    • Nausea, vomiting.
    • Dysphagia (if proximal tumor).
    • Occult GI bleeding → anemia.
    • Virchow’s node (left supraclavicular lymphadenopathy).

4. Diagnostic Approach

Key Investigations

  • Endoscopy with Biopsy:
    • Gold standard for diagnosis.
    • Obtain ≥6 biopsy samples from the lesion margins and central regions.
  • Endoscopic Ultrasound (EUS):
    • Evaluates depth of tumor invasion (T stage) and lymph node involvement (N stage).
  • Imaging for Staging:
    • CT Scan (Chest, Abdomen, Pelvis): Rules out distant metastases.
    • PET-CT: Used when CT findings are ambiguous.
    • Laparoscopy: Assesses for peritoneal and hepatic metastases, especially for locally advanced disease.

5. Staging and Classification

  • AJCC/UICC TNM Staging:

T Stage

Description

T1

Invades lamina propria, muscularis mucosae, or submucosa.

T2

Invades muscularis propria.

T3

Invades subserosa.

T4

Invades serosa or adjacent structures.
  • N Stage: Number of regional lymph nodes involved.
  • M Stage: Presence of distant metastases.

6. Management

Early-Stage Disease (T1, No Lymph Node Involvement)

  • Endoscopic Resection:
    • Endoscopic Mucosal Resection (EMR) or Endoscopic Submucosal Dissection (ESD):
      • Indications: Lesions <2 cm, confined to mucosa, with no ulceration and low lymph node metastasis risk.
      • EMR for lesions <1 cm; ESD for larger lesions or those with superficial submucosal invasion.

Locally Advanced Disease (T2–T4, N+)

  • Surgery:
    • Subtotal Gastrectomy for distal tumors.
    • Total Gastrectomy for proximal tumors.
    • Transhiatal Total Gastrectomy for GOJ (Type II) tumors.
    • D2 lymphadenectomy (removal of ≥15 lymph nodes).
  • Perioperative Chemotherapy:
    • FLOT regimen (5-FU, leucovorin, oxaliplatin, docetaxel): Standard for resectable tumors.
    • Alternative: Epirubicin, cisplatin, and capecitabine (ECX) for selected patients.

Metastatic Disease (M1)

  • Systemic Chemotherapy:
    • Platinum-fluoropyrimidine doublet (e.g., cisplatin/5-FU).
    • Addition of trastuzumab for HER2-positive tumors.
    • Second-line options: Ramucirumab (VEGF receptor 2 inhibitor), paclitaxel.
  • Immunotherapy:
    • PD-1 inhibitors (nivolumab, pembrolizumab) for patients with PD-L1-positive tumors.

7. Surveillance and Follow-Up

  • Post-Treatment Surveillance:
    • Clinical assessments every 3–6 months for the first 2 years.
    • Imaging (CT, PET-CT) and endoscopy as needed.
  • ESMO Guidelines:
    • Routine follow-up with imaging in high-risk patients.
    • Symptom-based follow-up for low-risk patients.
  • Screening and Prevention:
    • Eradication of H. pylori reduces gastric cancer risk.
    • Consider genetic testing for patients with a family history of hereditary diffuse gastric cancer.

References

  1. British Society of Gastroenterology (BSG) Guidelines.
  2. European Society for Medical Oncology (ESMO) Guidelines.
  3. Annals of Oncology Review on Gastric Cancer.


Figure 1: GI lymphoma.

 


Figure 2: Malignant gastric stricture.

 

Figure 3: Malignant gastric ulcer.


Figure 4: linitis with acute GI bleeding.