Stomach / Intestinal Cancer

The Function of the Stomach and Complications Associated with Stomach Cancer

The stomach is a vital digestive organ located between the esophagus and the small intestine. Its primary role is to break down food using gastric acid and digestive enzymes, initiating the process of nutrient absorption. It also acts as a temporary food reservoir, regulates the release of partially digested contents into the intestines, and plays a role in intrinsic factor secretion essential for vitamin B12 absorption. When affected by disease such as stomach (gastric) cancer, its function becomes impaired—leading to nutritional deficits, weight loss, gastrointestinal bleeding, and in advanced stages, widespread metastasis that can affect multiple organ systems.

Categories Associated With Primary and Secondary Stomach Tumors

Primary Stomach Cancer:
This refers to cancer that begins in the stomach. The most common types include:

  • Adenocarcinoma, originating from the glandular cells lining the stomach (90–95% of cases).

  • Other rare types include gastrointestinal stromal tumors (GISTs), lymphomas, and neuroendocrine tumors.

Secondary (Metastatic) Stomach Cancer:
Cancers from other organs such as the breast, lung, or esophagus may spread to the stomach. This is less common and typically indicates an advanced stage of primary malignancy.

Causes and Risk Factors for Stomach Cancer

Stomach cancer development is usually a slow process and influenced by a mix of genetic and environmental factors. Notable risk factors include:

  • Chronic infection with Helicobacter pylori (H. pylori)

  • Gastric ulcers, chronic atrophic gastritis, or intestinal metaplasia

  • Family history of gastric cancer

  • Smoking and excessive alcohol consumption

  • Diets high in smoked, salted, or pickled foods and low in fruits and vegetables

  • Pernicious anemia, caused by vitamin B12 deficiency

  • Previous stomach surgery or polyps

  • Epstein-Barr virus (EBV) association in some subtypes

Signs and Symptoms of Stomach Cancer

Early-stage stomach cancer often goes unnoticed due to vague or non-specific symptoms. As the disease progresses, more evident signs appear:

  • Persistent indigestion, heartburn, or discomfort in the upper abdomen

  • Early satiety (feeling full after eating a small amount)

  • Unexplained weight loss

  • Nausea or vomiting, sometimes with blood

  • Black or tarry stools (melena) due to gastrointestinal bleeding

  • Loss of appetite and fatigue

  • Abdominal swelling or a palpable mass in advanced cases

Diagnosis of Stomach Cancer

Diagnosis involves several steps to detect, classify, and stage the cancer:

  • Medical history and physical examination, especially for upper gastrointestinal symptoms

  • Upper endoscopy (esophagogastroduodenoscopy or EGD) with biopsy—crucial for visualizing the tumor and obtaining tissue samples

  • Endoscopic ultrasound (EUS) to assess depth of invasion

  • CT, MRI, or PET-CT scans for evaluating lymph node involvement or metastasis

  • Laparoscopy may be used to assess operability and detect peritoneal spread

  • Tumor markers such as CEA or CA 19-9, though non-specific, may help monitor treatment

Staging: TNM classification is used to determine tumor spread and guide treatment planning.

Best Treatment for Stomach Cancer

Treatment decisions are based on the cancer’s location, stage, subtype, and patient health.

A. Traditional Treatments

  1. Surgical Procedures

    • Subtotal or total gastrectomy (partial or complete removal of the stomach) is the cornerstone for curative treatment in resectable tumors.

    • Lymphadenectomy (removal of regional lymph nodes) is essential for staging and prognosis.

    • Surgery may also include reconstructive procedures like Roux-en-Y gastrojejunostomy for continuity.

  2. External Beam Radiation Therapy

    • Typically used after surgery (adjuvant therapy) or before surgery (neoadjuvant therapy) in combination with chemotherapy.

    • May help relieve symptoms such as bleeding or pain in palliative settings.

  3. Systemic Chemotherapy

    • Commonly used before (neoadjuvant) or after surgery (adjuvant), or as primary treatment in unresectable/metastatic cases.

    • Drugs often include 5-FU, capecitabine, oxaliplatin, cisplatin, or docetaxel.

B. Advanced Treatments for Stomach Cancer

  1. Targeted Therapies

    • Trastuzumab for HER2-positive gastric cancers improves survival in metastatic disease.

    • Ramucirumab targets VEGF receptors, inhibiting tumor blood vessel formation.

    • Other agents under investigation target FGFR2, CLDN18.2, and MET pathways.

  2. Immunotherapy

    • Checkpoint inhibitors (e.g., pembrolizumab, nivolumab) are used for PD-L1 positive or MSI-high gastric cancers.

    • Immunotherapy may be used alone or in combination with chemotherapy for advanced-stage disease.

  3. Brachytherapy or Intraluminal Radiation

    • May be used in select advanced cases to control bleeding or improve swallowing.

  4. Minimally Invasive and Microinvasive Approaches

    • Laparoscopic gastrectomy with lymph node dissection is increasingly used in early-stage cancers with favorable outcomes.

    • Endoscopic mucosal resection (EMR) or submucosal dissection (ESD) is possible for small, superficial tumors.

Prevention and Lifestyle Management

Primary prevention and lifestyle measures include:

  • H. pylori detection and eradication, especially in high-risk populations

  • Balanced diet rich in fresh fruits and vegetables; low in salt, smoked, and processed foods

  • Smoking cessation and limited alcohol intake

  • Regular screenings for people with family history or genetic predisposition (e.g., Lynch syndrome, familial adenomatous polyposis)

  • Managing gastric inflammation or ulcers with medical attention

  • Physical activity and healthy weight maintenance

Prognosis and Survival Rates

Prognosis depends heavily on stage at diagnosis:

  • Early-stage (I) gastric cancer: 5-year survival rate of 60%–90%

  • Locally advanced disease (II–III): 5-year survival drops to 30%–50%

  • Advanced/metastatic (Stage IV): 5-year survival often <10%

  • Combining surgery, systemic therapies, and targeted or immune-based treatments continues to improve survival and quality of life.

Conclusion

Stomach cancer poses serious challenges due to its often subtle early symptoms and aggressive progression. However, early diagnosis through endoscopy, proper staging, and a multimodal treatment approach can significantly enhance outcomes. Innovations in targeted therapy, immunotherapy, and minimally invasive surgery offer promising avenues for improved survival and long-term control. Preventive measures and awareness are essential in reducing incidence and enabling early detection.