What Is Stomach Cancer?

Carrie Madormo, RN, MPH
·10 min read

Medically reviewed by Doru Paul, MD

Stomach cancer is a type of cancer that begins in the lining of the stomach, the organ that is located between the esophagus and the small intestine. The stomach helps our bodies digest food by mixing it with stomach acid. Researchers do not know the exact cause of stomach cancer, but certain risk factors, like a family history or being born male, may increase your odds of developing the condition. About two-thirds of people diagnosed with stomach cancer are over age 65.

Stomach cancer symptoms can vary and may include indigestion and stomach pain. Most people with stomach cancer only experience mild symptoms in the early stages. Stomach cancer is usually not diagnosed until later stages when it is more difficult to treat. Treatment options may include surgery, chemotherapy, and radiation therapy. In the United States, there are about 26,500 new cases of stomach cancer each year.

<p>Illustration by Dennis Madamba for Health</p>

Illustration by Dennis Madamba for Health

Types

There are different types of stomach cancer, and they can develop in different areas of the stomach. The most common type is adenocarcinoma, making up about 90% to 95% of all stomach cancer cases. This type of cancer starts in the mucosa, the innermost lining of the stomach.

There are two types of adenocarcinomas in the stomach: intestinal adenocarcinoma and diffuse adenocarcinoma. Intestinal adenocarcinoma usually has a better prognosis because the cancer cells have certain mutations that make them easier to treat with targeted therapy. Diffuse adenocarcinoma tends to spread more quickly and is more difficult to treat.

Other types of stomach cancer include:

  • Gastrointestinal stromal tumors (GISTs): GISTs are tumors that can develop anywhere in the gastrointestinal tract. They are most common in the stomach.

  • Neuroendocrine tumors (NETs): NETs are tumors that behave like both nerve cells and endocrine (hormone-producing) cells. They tend to grow slowly.

  • Lymphomas: Lymphoma is a type of cancer that begins in the immune cells (lymphocytes). Because lymphocytes line the digestive tract, lymphomas can develop in the stomach. 

Stomach Cancer Symptoms

Symptoms of stomach cancer tend to be mild in the early stages, and they are often mistaken for other conditions. As cancer spreads and becomes more advanced, more symptoms occur.

Early-stage stomach cancer may cause no symptoms or indigestion and abdominal discomfort. As cancer progresses, late-stage symptoms may include:

Many of these symptoms may seem like they are related to acid reflux or a stomach ulcer. If you develop any symptoms of stomach cancer, see your healthcare provider.

What Causes Stomach Cancer?

Stomach cancer occurs when cells in the lining of the stomach mutate and begin to grow and spread. Researchers do not know the exact cause of stomach cancer, and research is ongoing.

There is strong evidence that stomach cancer is associated with infection with the bacteria Helicobacter pylori (commonly called H. pylori). This bacteria lives in the digestive tract and may turn some of the substances in food into chemicals that lead to DNA mutations. These mutations may lead to precancerous conditions in the stomach.

There are pre-cancerous changes that may occur in the stomach lining and lead to stomach cancer, including:

  • Atrophic gastritis: Occurs when there is a lack of gland cells in the stomach; usually caused by infection with Helicobacter pylori

  • Intestinal metaplasia: Happens when the cells in the stomach lining are replaced with cells that look like those that line the intestine; may be related to Helicobacter pylori infection

  • Dysplasia: Occurs when there is damage to the DNA of the cells and causes the cells to grow larger than normal; the cells also change their shape 

Related: Signs and Symptoms of H. Pylori Infection

Risk Factors

There are several known risk factors for stomach cancer. Some of the risk factors, like smoking and diet choices, can be changed. However, many of the risk factors like age and family history cannot be changed.

Known risk factors for stomach cancer include:

  • Age over 65

  • Male sex

  • History of an H. pylori infection

  • History of stomach inflammation

  • A diet rich in salted, smoked, or pickled foods

  • Smoking

  • An excess of visceral adipose tissue, which is body fat that directly surrounds the organs

  • Excessive alcohol consumption

  • History of stomach surgery

  • Stomach polyps (excess tissue growth in the stomach)

  • Pernicious anemia, which is an autoimmune condition that causes larger-than-normal red blood cells that inhibit oxygen transport throughout your body

  • History of Epstein-Barr virus (EBV), a common, contagious herpes virus

  • Family history of stomach cancer

Inherited gene mutations may also raise the risk of stomach cancer. People with the following genetic conditions may have an increase risk:

  • Hereditary diffuse gastric cancer (HDGC)

  • Lynch syndrome

  • Familial adenomatous polyposis (FAP)

  • Gastric adenoma and proximal polyposis of the stomach (GAPPS)

  • Li-Fraumeni syndrome

  • Peutz-Jeghers syndrome (PJS)

Diagnosis

Because stomach cancer does not usually cause symptoms in the early stages, it is often diagnosed in the later stages. If you have developed any prolonged symptoms of stomach cancer, your healthcare provider will start with a physical exam to look for any signs of cancer. They will also conduct a thorough medical history to ask about your risk factors and symptoms.

Tests used to diagnose stomach cancer include:

  • Blood test: A complete blood count (CBC) may be drawn to look for anemia (low red blood cell count). This could indicate bleeding in the stomach.

  • Upper endoscopy: A thin, flexible tube with a light and a camera at the end is passed down the throat to inspect the inner lining of the esophagus and the stomach.

  • Biopsy: During an upper endoscopy, your healthcare provider may remove small samples from any abnormal areas of the stomach. These samples are then sent to a lab for testing.

  • HER2 testing: During a biopsy, cells may be checked for HER2, a growth-promoting protein that may be present in cancer cells. Other gene or protein tests may be used as well.

  • Laparoscopy: A laparoscopy may be used to confirm if the cancer is only in the stomach and has not spread. This test is often used before surgery.

Imaging tests used to diagnose stomach cancer include:

  • Upper gastrointestinal (GI) series: X-ray to inspect the inner lining of the esophagus, stomach, and part of the small intestine to look for abnormal areas

  • Computed tomography (CT) scan: Provides detailed images of the stomach and can detect if cancer has spread to nearby organs like the liver

  • Endoscopic ultrasound: Used to determine how far cancer has spread through the wall of the stomach or nearby lymph nodes

  • Positron emission tomography (PET) scan: Detects where cancer cells have spread

  • Magnetic resonance imaging (MRI): Not commonly used but may show detailed pics of tumors in the liver

  • Chest X-ray: Detects if cancer has spread to the lungs

Regular screening for stomach cancer is usually not recommended in the United States. This is because, due to the relatively low incidence of stomach cancer, the risks of screening generally outweigh the benefits.

Treatments for Stomach Cancer

There are several treatment options for stomach cancer. When caught early, the goal of treatment is to reach remission (vast reduction or elimination of cancer cells in your body). If stomach cancer is diagnosed in the later stages, the goal of treatment may be to relieve symptoms such as pain or trouble eating.

Treatment options for stomach cancer include:

  • Surgery: Surgery is a common treatment for stomach cancer, especially if the cancer has not spread to other areas of the body. Surgery may be performed to remove cancer cells and part of the stomach. It may also be used to relieve pain.

  • Chemotherapy: Chemotherapy may be used before surgery to shrink the tumor size, after surgery to kill any remaining cancer cells, or as the primary treatment for stomach cancer.

  • Radiation therapy: Like chemotherapy, radiation therapy may be used before or after surgery. If surgery is not an option, radiation therapy may be used to shrink the tumor.

  • Targeted therapy: Targeted therapy targets certain proteins, such as HER2, in cancer cells. It may be used alone or with chemotherapy.

  • Immunotherapy: Immunotherapy uses medication to boost the body’s immune response to fight cancer. Immune checkpoint inhibitors are drugs that help the body attack cancer cells while ignoring healthy cells. 

Prevention

It is often not possible to prevent stomach cancer, but there are steps that you can take to lower your risk. Tips to lower your odds of developing stomach cancer include:

  • Nutrition: A diet rich in processed or pickled foods may raise the risk of stomach cancer. Focus on fresh, whole foods like fruits, vegetables, whole grains, lean proteins, low-fat dairy, and healthy fats. Try to avoid red or processed meat and sugary beverages.

  • Physical activity: Daily exercise lowers the risk of stomach cancer. It may lower the risk of other types of cancer as well.

  • Limiting alcohol consumption: Avoiding or limiting alcohol may lower the risk of several types of cancer including stomach cancer.

  • Avoid tobacco: Smoking increases the risk of stomach cancer, especially in the upper part of the stomach near the esophagus. Work with your healthcare provider to quit if needed.

  • H. pylori Treatment: Infection with H. pylori is a known risk factor for stomach cancer. This bacteria can be treated successfully with antibiotics

Comorbid Conditions

Comorbid conditions refer to conditions that you may develop when you have stomach cancer. People with stomach cancer may be more likely to develop the following conditions:

A 2018 study found that people with pulmonary disease had a significantly higher risk of experiencing complications after stomach cancer surgery than those without lung disease. 

Living With Stomach Cancer

Going through the diagnostic process and treatment of stomach cancer can be an overwhelming and grueling experience. Once you have finished your treatment protocol, you may continue to experience symptoms and complications. It will be important to continue to work closely with your healthcare team, including your oncologist (a medical doctor who specializes in cancer).

People who have gone through treatment for stomach cancer may experience “dumping syndrome.” Dumping syndrome refers to the symptoms of nausea, diarrhea, sweating, and flushing after eating. It happens when food passes quickly through the digestive tract. This may be a result of having part of the stomach removed with surgery. Your healthcare provider and dietitian can help to develop a treatment plan for dumping syndrome.

If you have a feeding tube (jejunostomy tube, or J-tube) in the small intestine following treatment, continue to work with your nutrition team. A J-tube is used to provide liquid nutrition to prevent too much weight loss and to give needed nutrients.

Other tips for living with stomach cancer include:

  • Follow-up care: Continue to participate in regular medical care to monitor for any signs of cancer and to address any medication side effects. Once treatment is finished, your healthcare team will likely recommend appointments every 3 to 6 months for a physical exam and any necessary tests.

  • Nutrition care: Stomach cancer and its treatment may affect how you eat and absorb food. Nausea is a common side effect. Work with a dietitian to ensure you consume enough nutrients, and consider eating small, frequent meals instead of large ones.

  • Healthy lifestyle: To lower your risk of developing cancer in the future, eat a healthy diet rich in fruits and vegetables, stay in a healthy weight range, get regular exercise, and avoid alcohol and tobacco.

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