Stomach cancer, also known as gastric cancer, originates in the lining of the stomach. This organ, situated between the esophagus and the small intestine, plays a central role in digestion by mixing food with stomach acids and enzymes. Though the exact cause remains unknown, researchers have identified a number of contributing factors, including age, gender, family history, infections, and lifestyle habits. Most people diagnosed with stomach cancer are over 65 years old, and men are more commonly affected than women.

This cancer tends to develop slowly and may not produce noticeable symptoms until it has reached an advanced stage, making early diagnosis difficult. Treatment options vary depending on the stage but typically include surgery, chemotherapy, radiation therapy, targeted therapy, and immunotherapy.

Types

Stomach cancer comes in several forms, but the vast majority are adenocarcinomas, which start in the mucosal lining of the stomach. There are two main subtypes:

  • Intestinal adenocarcinoma: Tends to grow more slowly and respond better to treatment.
  • Diffuse adenocarcinoma: Grows more aggressively and spreads faster.

Other, less common types include:

  • Gastrointestinal stromal tumors (GISTs): Typically arise in the stomach wall and originate from interstitial cells of Cajal.
  • Neuroendocrine tumors (NETs): Arise from hormone-producing cells and usually progress slowly.
  • Lymphomas: Develop in immune system cells (lymphocytes) located in the stomach lining.

Symptoms

Symptoms of stomach cancer often mimic common digestive issues, which makes it hard to detect early. In early stages, there may be no symptoms at all or only mild discomfort. As the cancer advances, common symptoms include:

  • Indigestion or persistent heartburn
  • Nausea and vomiting (sometimes with blood)
  • Bloating after meals
  • Feeling full after eating small amounts
  • Loss of appetite
  • Unexplained weight loss
  • Blood in stool or black, tarry stools
  • Abdominal pain or swelling
  • Fatigue or general weakness
  • Difficulty swallowing

If any of these symptoms persist for more than a few weeks, it's important to seek medical evaluation.

Causes

Stomach cancer develops when healthy cells in the stomach lining acquire DNA mutations that prompt abnormal growth. These mutated cells can form tumors and spread to nearby tissues or organs.

One of the most well-established risk factors is Helicobacter pylori infection, a common bacterial infection that can lead to chronic inflammation and pre-cancerous changes in the stomach lining, such as:

  • Atrophic gastritis: A condition characterized by a loss of gland cells.
  • Intestinal metaplasia: Stomach cells begin to resemble intestinal cells.
  • Dysplasia: Cells grow abnormally and have the potential to become cancerous.

Risk Factors

Several factors can increase the likelihood of developing stomach cancer. Some can be managed, while others, such as age and genetics, cannot:

  • Age over 65
  • Being male
  • H. pylori infection
  • Long-standing inflammation of the stomach lining
  • Diet high in salted, smoked, or pickled foods
  • Smoking
  • Obesity, especially with high levels of visceral fat
  • Excessive alcohol use
  • History of stomach surgery or stomach polyps
  • Pernicious anemia (a vitamin B12 deficiency due to autoimmune gastritis)
  • Infection with Epstein-Barr virus (EBV)
  • Family history of stomach cancer

Genetic syndromes associated with increased risk:

  • Hereditary diffuse gastric cancer (HDGC)
  • Lynch syndrome
  • Familial adenomatous polyposis (FAP)
  • Peutz-Jeghers syndrome (PJS)
  • Li-Fraumeni syndrome
  • GAPPS (gastric adenoma and proximal polyposis of the stomach)

Diagnosis

Diagnosing stomach cancer typically involves a combination of physical exams, lab tests, imaging, and endoscopic procedures:

  • Physical exam and medical history: To evaluate symptoms and identify risk factors.
  • Blood tests: Including complete blood count (CBC) to detect anemia.
  • Upper endoscopy: A camera-equipped flexible tube examines the stomach lining.
  • Biopsy: Tissue samples are taken during endoscopy and sent to a lab.
  • HER2 testing: Checks for protein markers that can guide treatment.
  • Laparoscopy: A minimally invasive procedure to evaluate tumor spread.

Imaging tests may include:

  • Upper GI series (barium swallow): X-rays of the digestive tract
  • CT scan: To evaluate tumor size and metastasis
  • Endoscopic ultrasound: Assesses depth of tumor invasion
  • PET scan: Identifies areas of cancer activity
  • MRI or chest X-ray: To detect spread to other organs

Treatment

Treatment depends on the type, location, and stage of the cancer, as well as the patient’s overall health. The main treatments include:

  • Surgery: Can be curative in early stages; includes partial or total gastrectomy.
  • Chemotherapy: Used before surgery (neoadjuvant) to shrink tumors or after surgery (adjuvant) to kill remaining cells.
  • Radiation therapy: Often combined with chemo to increase effectiveness.
  • Targeted therapy: Medications like trastuzumab (for HER2-positive tumors) attack specific cancer cell markers.
  • Immunotherapy: Drugs such as immune checkpoint inhibitors boost the body’s ability to recognize and destroy cancer cells.

The treatment goal may be remission in early stages or symptom control in more advanced stages.

Prevention

Although not all cases are preventable, you can reduce your risk through lifestyle choices and medical interventions:

  • Healthy diet: Emphasize fresh fruits, vegetables, whole grains, and lean proteins.
  • Limit intake of processed, salty, or pickled foods.
  • Avoid tobacco and limit alcohol consumption.
  • Maintain a healthy weight and exercise regularly.
  • Seek treatment for H. pylori if diagnosed.

Early detection of precancerous conditions can also help prevent stomach cancer from developing.

Comorbidities

People with stomach cancer may have or develop additional health conditions, which can complicate treatment and recovery. Common comorbid conditions include:

  • High blood pressure
  • Type 2 diabetes
  • Chronic liver conditions (e.g., hepatitis or cirrhosis)
  • Lung disease
  • Heart disease

These comorbidities may affect treatment choices and outcomes, so they require careful management.

Living With It

Living with stomach cancer often involves ongoing treatment and symptom management, even after primary therapy is completed. Long-term care may include:

  • Follow-up appointments: Every 3–6 months for exams and imaging
  • Nutritional support: Many patients require help from dietitians due to reduced stomach capacity or altered digestion
  • Dumping syndrome management: Caused by rapid gastric emptying post-surgery, symptoms include nausea, diarrhea, and sweating
  • Feeding tube support (J-tube): Provides nutrition when normal eating is compromised
  • Lifestyle adaptation: Small, frequent meals, hydration, and vitamin supplements

Emotional and psychological support is also important, and many benefit from counseling or joining cancer support groups.

Conclusion

Stomach cancer is a challenging disease due to its late presentation and complex treatment pathways. However, with early detection, targeted therapies, and supportive care, many patients can achieve meaningful improvements in quality of life and longevity.

If you or someone you know has symptoms or risk factors for stomach cancer, consult a healthcare provider for evaluation and guidance. Proactive care can make a significant difference in outcomes.