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Stomach cancer (gastric cancer) develops in the lining of the stomach, often growing slowly over the years. While global incidence has declined, it remains a leading cause of cancer death worldwide, especially in East Asia. Here’s a concise yet comprehensive overview:

  • Types
    • Adenocarcinoma
      • 90–95% of cases. Arises from glandular cells in the stomach lining. Subtypes:
        • Intestinal: Gland-forming; linked to H. pylori, diet.
        • Diffuse: Infiltrating cells (signet ring); aggressive, genetic links (e.g., CDH1 mutations).
    • Other Types:
      • Gastrointestinal Stromal Tumor (GIST): Starts in interstitial cells.
      • Lymphoma: MALT lymphoma (often H. pylori-related).
      • Carcinoid/NETs: Neuroendocrine tumors.
  • Symptoms
    • Early: Often none or vague (indigestion, bloating).
    • Advanced:
      • Persistent abdominal pain/discomfort, unintentional weight loss.
      • Early satiety (feeling full after small meals), nausea/vomiting.
      • Dysphagia (if cardia tumor), melena (dark stools from bleeding), anemia.

🚨 Red Flags: Persistent indigestion + weight loss or vomiting blood warrants urgent endoscopy

  • Risk Factors
    • Helicobacter pylori Infection: #1 risk (causes chronic inflammation → precancerous changes).
    • Diet: High-salt foods (pickled/smoked meats), low fruit/vegetable intake, processed meats (nitrates).
    • Tobacco & Alcohol: Smokers have 2× higher risk.
    • Obesity & GERD: ↑ Risk for proximal (cardia) tumors.
    • Genetics:
      • Hereditary Diffuse Gastric Cancer (HDGC): CDH1 gene mutation (↑ diffuse-type risk).
      • Lynch Syndrome, FAMMM.
    • Other: Pernicious anemia, chronic gastritis, prior stomach surgery.
  • Diagnosis
    • Endoscopy (+ Biopsy):
      • Gold standard. Visualizes tumors, takes tissue samples.
    • Imaging:
      • CT Chest/Abdomen/Pelvis: Staging (lymph nodes, metastasis).
      • Endoscopic Ultrasound (EUS): Assesses tumor depth (T-stage) and nodal spread.
      • PET-CT: Detects distant metastases.
    • Biomarker Testing:
      • HER2/neu: For targeted therapy (20% of cases).
      • MSI/PD-L1: Guides immunotherapy use.
    • H. pylori Testing: Breath, stool, or biopsy tests.
  • Treatment:
    • Localized Disease (Stages I–III):
      • Surgery:
        • Subtotal or Total Gastrectomy: Removal of part/all stomach + lymph nodes (D2 dissection preferred in Asia).
        • Reconstruction: Roux-en-Y bypass.
      • Adjuvant Therapy:
        • Chemoradiation (e.g., FLOT regimen: 5-FU/leucovorin/oxaliplatin/docetaxel) pre/post-surgery.
    • Metastatic Disease (Stage IV):
      • Chemotherapy:
        • 1st-line: FLOT or FOLFOX/CAPOX.
        • HER2+ Tumors: Trastuzumab + chemo.
      • Immunotherapy:
        • PD-L1+ Tumors: Pembrolizumab ± chemo (1st-line).
        • MSI-H/dMMR Tumors: Pembrolizumab (any line).
      • Targeted Therapy:
        • Ramucirumab (VEGFR2 inhibitor) ± paclitaxel (2nd-line).
        • Fam-trastuzumab deruxtecan (HER2-low tumors).
      • Palliative Care:
        • Stents for obstructions, paracentesis for ascites, nutrition support.
  • Prognosis & Key Factors
    • Overall 5-Year Survival: ~32% (lower in Western vs. Asian countries due to late diagnosis).
    • Favorable Factors:
      • Early stage (T1a), intestinal subtype, H. pylori eradication, R0 resection.
    • Poor Prognosis:
      • Diffuse subtype, signet ring cells, peritoneal involvement, HER2-negative.
  • Prevention & Screening
    • H. pylori Eradication: Antibiotic therapy reduces risk by 30–50%.
    • Diet: Limit processed/salted meats; increase fruits, vegetables, fiber.
    • Screening (High-Risk Areas):
      • East Asia (Japan, Korea): National endoscopy programs (↓ mortality by 50%).
    • Genetic Testing: For CDH1 carriers (prophylactic gastrectomy considered).
      Multidisciplinary care (surgery, oncology, GI, nutrition) is essential.

Frequently Asked Questions (FAQ)

Q1: What is the most important risk factor for stomach cancer?
Infection with Helicobacter pylori (H. pylori) is the leading risk factor for stomach cancer, causing chronic inflammation that can progress to precancerous changes over many years. H. pylori infection is very common worldwide and can be diagnosed with breath, stool, or biopsy tests, and treated with antibiotics — reducing gastric cancer risk by 30–50%.

Q2: Why is stomach cancer more common in East Asian countries?
Countries like Japan, Korea, and China have higher rates of stomach cancer, partly due to dietary habits (high consumption of salted, pickled, and smoked foods), a high prevalence of H. pylori infection, and genetic predispositions. Some of these countries operate national endoscopic screening programs that have successfully reduced stomach cancer mortality by detecting it earlier.

Q3: What are the early symptoms of stomach cancer?
Early gastric cancer often produces no or very vague symptoms such as indigestion, bloating, or mild abdominal discomfort — easily mistaken for common gastric issues. More specific warning signs that should prompt urgent endoscopy include persistent abdominal pain with unintentional weight loss, vomiting blood, or black/tarry stools.

Q4: What is HER2 testing in stomach cancer?
HER2 (human epidermal growth factor receptor 2) is a protein overexpressed in about 20% of gastric adenocarcinomas. HER2-positive tumors can be targeted with trastuzumab (Herceptin), an antibody drug that has improved survival in HER2-positive advanced gastric cancer when combined with chemotherapy. HER2 testing is routinely recommended in advanced gastric cancer.

Q5: What is the FLOT chemotherapy regimen?
FLOT (5-fluorouracil, leucovorin, oxaliplatin, and docetaxel) is a four-drug combination chemotherapy regimen that has become the standard perioperative (before and after surgery) treatment for locally advanced, resectable gastric or gastroesophageal junction adenocarcinoma. Studies have shown it improves survival compared to older three-drug regimens.

Q6: What is a gastrectomy and what happens after surgery?
Gastrectomy is the surgical removal of part (subtotal) or all (total) of the stomach, along with regional lymph nodes. After total gastrectomy, the esophagus is connected directly to the small intestine (Roux-en-Y reconstruction). Patients must adjust to smaller, more frequent meals and may require vitamin B12 supplementation for life, since the stomach normally aids in its absorption.

Q7: What is the prognosis for stomach cancer?
The overall 5-year survival rate for stomach cancer is approximately 32% in Western countries, partly because many cases are diagnosed at advanced stages. However, early-stage stomach cancer (confined to the stomach wall) has a much better prognosis, with 5-year survival rates exceeding 90% in countries with active early detection programs. Tumor subtype, stage, and response to treatment are key prognostic factors.

Medical Disclaimer

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