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Understand stomach (gastric) cancer

In the United States, stomach cancer is diagnosed in about 26,500 patients each year

The information on this page may help you gain a better understanding of your stomach cancer diagnosis and what’s happening to your body. This may help when making important decisions with your doctor.

On this page:
What is stomach cancer?
Risk factors
Screening and diagnosis
Stomach cancer staging
Common types of treatment
Questions to ask your doctor

From Harvard Health Publishing

What is stomach cancer?

The stomach is a hollow organ that sits between the esophagus (the tube that goes from the back of the mouth to the top of the stomach) and the small intestine. Considered a part of the digestive system, the stomach helps break down the food you eat through enzymes and acids it produces.

Stomach cancer, also known as gastric cancer, is the formation of malignant (cancer) cells in the lining of the stomach. Most stomach cancers are caught after the cancer has spread to other parts of the body.

Types of stomach cancer

The most common form of stomach cancer is called adenocarcinoma (pronounced “a-deh-noh-KAR-sih-NOH-muh’), in which cells from the innermost lining of the stomach grow uncontrollably.

Non-adenocarcinoma stomach cancers can start in different types of cells, and are much rarer than adenocarcinomas. These include gastrointestinal stromal tumors (GISTs), neuroendocrine tumors (NETs), and lymphomas.

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Risk factors for stomach cancer

Scientists have identified certain risk factors for stomach cancer. Anything that increases the chance of getting a disease is called a risk factor.

Stomach cancer is almost twice as common in men as in women. Most people are older than 55 years when diagnosed.

Rates of stomach cancer are lower in North America compared with the other continents. In the US, the number of new cases per year of stomach cancer is higher in Black, Hispanic, American Indian, and Asian people compared with non-Hispanic White people.

Other risk factors can include:

Helicobacter pylori (H. pylori) infection: H. pylori bacteria are common in the stomach lining and can cause stomach ulcers, inflammation of the stomach, and stomach cancer. A small percentage of people with this condition develop precancerous stomach cells that can progress to full-blown cancer

Weight: Being overweight or obese may increase risk

Diet: A diet that is high in salty, smoked, pickled or salt-preserved foods, and/or high in processed or grilled meats, increases stomach cancer risk

Alcohol use: Drinking 3 or more alcoholic beverages a day may increase stomach cancer risk

Tobacco: The rate of occurrence of stomach cancer is approximately doubled in smokers

Previous stomach surgery or health conditions: These issues, including pernicious anemia or achlorhydria, may increase stomach cancer risk. Pernicious anemia occurs when the stomach cannot absorb enough vitamin B12. This causes a severe decrease of red blood cells. Achlorhydria happens when there is no hydrochloric acid in the stomach, which impairs the digestive process

Talk to your doctor if you think you may be at increased risk.

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Screening and diagnosis

In the US, there are currently no routine screening recommendations for stomach cancer. However, there are clinical trials looking at ways to screen for this cancer. Cancers diagnosed at an earlier stage may mean a better chance of recovery, while more advanced cancers can present additional challenges.

Keep in mind that having one or more of the risk factors listed above doesn’t mean you will get stomach cancer. But if you think you may be at increased risk for stomach cancer, consider asking your doctor about getting screened for stomach cancer. The following diagnostic approaches may be used. 

Medical history/physical exam

Your health care provider may begin by taking your medical and family history and performing a complete physical examination.

Imaging

Your doctor may want to see pictures of your stomach and other organs. Common imaging tests include:

Barium swallow: An x-ray of the stomach and esophagus is taken after the patient drinks a liquid that contains barium, which then coats the stomach and esophagus. Barium is a metallic compound that makes organs easier to be photographed by an x-ray.

Scoping tests: Some images are taken with instruments called scopes that are inserted into the body to take photos. An endoscope, a thin instrument with a light, goes through the mouth to view the stomach and esophagus. A laparoscope goes through a tiny incision in your abdomen.

CT, ultrasound, PET scans, and others: A computed tomography (CT or CAT) scan uses x-rays to take pictures of the inside of the body. An ultrasound uses high-energy soundwaves to create images of the inside of your body. A positron emission tomography (PET) scan uses a radioactive drug called a tracer, which is injected into a vein and shows where cancer cells are in the body. Other imaging techniques that use different technology may also be used.

Blood tests

Your health care provider may take a blood sample through a needle placed in your vein. The tests can show signs of disease and how well your internal organs are working.

Complete blood count (CBC): This test measures the number of red and white blood cells, as well as platelets, in your blood.

Serum pepsinogen test: This is a blood test showing levels of serum pepsinogen, a substance that can signal a condition that may lead to stomach cancer.

Biopsy

During an endoscopy, a sample of tissue or fluid may be removed. Samples can be taken from the tumor, the wall of the stomach, or other locations. Then the samples are sent to a pathologist, an expert in examining cells under a microscope, for analysis.

Keep in mind that testing itself has risks, including the chance of getting a false-negative result, a false-positive result, or side effects of the tests.

Talk to your doctor about whether testing for stomach cancer makes sense for you.

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What Is a Cancer Biomarker?

Biomarkers commonly tested for in stomach cancer

If you’ve been diagnosed with stomach cancer, your doctor may order biomarker testing. A biomarker is a biological molecule which can be measured and is found in blood and other body fluids or tissue.

The presence and type of biomarkers found in your sample may help your doctor determine the treatment plan that is right for you.

Biomarkers commonly tested for in stomach cancer include:

  • TMB (tumor mutational burden)
  • HER2 (human epidermal growth factor receptor 2)
  • MSI/MMR (microsatellite instability/mismatch repair)
  • NTRK (neurotrophic receptor tyrosine kinase) gene fusions
  • PD-L1 (programmed death ligand 1)

Some of the biomarker tests your doctor may order are: 

  • FISH (fluorescence in situ hybridization)
  • IHC (immunohistochemistry)
  • NGS (next-generation sequencing)
  • PCR (polymerase chain reaction)

Ask your doctor about biomarker testing, molecular testing, or tumor profiling. These 3 phrases all refer to biomarkers.

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Stomach cancer staging: What is it and how does it work?

Staging is an important step in any patient’s diagnosis of stomach cancer and is used to help decide what treatment or treatments will be used to fight your cancer. Staging is a way of describing how advanced the cancer is and whether or not it has spread to other organs.  

Staging also helps the doctor determine your prognosis, which describes potential outcomes.

The 5 layers of the stomach lining

Picturing the stomach’s 5 layers of tissue and muscle may help you understand how stomach cancer normally progresses from earlier to advanced stages. In general, the cancer most often begins in the innermost layer of the stomach lining, the mucosa. As it reaches the outer layers of the stomach, or spreads to the lymph nodes, it becomes more severe.

The layers are shown in order from innermost to outermost, top to bottom.

  • Mucosa: Thick, innermost layer; has contact with food
  • Submucosa: Connective tissue, blood vessels, lymph vessels, and nerve cells
  • Muscularis: Soft tissue to help move food through the stomach
  • Subserosa: Connective tissue; supports the outermost membrane
  • Serosa: The outermost membrane; allows the stomach to move smoothly against other organs

The stages of stomach cancer

From the National Cancer Institute (NCI)

The information below is based on information originally published by the National Cancer Institute (NCI), the US government’s main agency for cancer research. Use this information to talk to your doctor about your specific stage of stomach cancer.

The stages of stomach cancer go from Stage 0 through Stage 4. The higher the number, the farther the cancer has spread.

Stage 0 stomach cancer

In Stage 0 stomach cancer, abnormal cells have been found in the mucosa, the innermost layer of the stomach wall. These cells are not cancerous yet, but these cells may turn into cancer and spread. Stage 0 cancer is also called carcinoma in situ (in situ is Latin for “in position”).

Stage 1 stomach cancer

Stage 1 stomach cancer is divided into 2 substages:

Stage 1A

  • Cancer has developed in the mucosa, the innermost layer of the stomach wall, and may have spread to the submucosa.

Stage 1B

  • Cancer has formed in the mucosa; it may have spread to submucosa (but not necessarily); and has spread to 1 or 2 nearby lymph nodes but not to other organs.

Or stage 1B can be

  • Cancer has formed in the mucosa of the stomach wall and has spread to the muscle layer of the stomach wall, but has not spread to lymph nodes or other organs.

Stage 2 stomach cancer

Stage 2 stomach cancer is divided into 2 substages:

Stage 2A

  • Cancer has spread to 3 to 6 nearby lymph nodes, but no other organs, and may have spread to the submucosa.

Or stage 2A can be

  • Cancer has spread to 1 or 2 nearby lymph nodes, but no other organs, and has spread to the muscularis layer (the thick muscle) of the stomach wall.

Or stage 2A can be

  • Cancer has spread to the subserosa layer (the layer next to the outermost layer) of the stomach wall but has not spread to any nearby lymph nodes or other organs.

Stage 2B

  • Cancer has spread to 7 to 15 nearby lymph nodes and may have spread to the submucosa layer of the stomach wall.

Or stage 2B can be

  • Cancer has spread to 3 to 6 nearby lymph nodes and has spread to the muscularis layer.

Or stage 2B can be

  • Cancer has spread to 1 or 2 nearby lymph nodes and has spread to the subserosa layer of the stomach wall.

Or stage 2B can be

  • Cancer has spread to the serosa layer (outermost layer) of the stomach wall but has not spread to any nearby lymph nodes.

Stage 3 stomach cancer

Stage 3 stomach cancer is divided into 3 substages:

Stage 3A

  • Cancer has spread to 7 to 15 nearby lymph nodes (but not to other organs) and has spread to the muscularis layer (the thick muscle) of the stomach wall.

Or stage 3A can be

  • Cancer has spread to 3 to 6 nearby lymph nodes (but not to other organs) and has spread to the subserosa layer (the next-to-outermost section) of the stomach wall.

Or stage 3A can be

  • Cancer has spread to 1 to 6 nearby lymph nodes (but not to other organs) and has spread to the serosa layer, which is the outermost layer of the stomach wall.

Or stage 3A can be

  • Cancer has spread to nearby organs, including the colon, liver, pancreas, kidney, small intestine, and/or others.

Stage 3B

  • Cancer has spread to 16 or more nearby lymph nodes (but not to other organs) and may have spread to the submucosa layer or to the muscle layer of the stomach wall.

Or stage 3B can be

  • Cancer has spread to 7 to 15 nearby lymph nodes (but not to other organs) and has spread to the subserosa or serosa layer of the stomach wall.

Or stage 3B can be

  • Cancer has spread to 1 to 6 nearby lymph nodes and to nearby organs (including the colon, liver, pancreas, kidney, small intestine, and/or others).

Stage 3C

  • Cancer has spread to 16 or more nearby lymph nodes (but not to other organs) and has spread to the subserosa or serosa layer of the stomach wall.

Or stage 3C can be

  • Cancer has spread to 7 or more nearby lymph nodes and nearby organs (including the colon, liver, pancreas, kidney, small intestine, and/or others).

Stage 4 stomach cancer

In Stage 4 stomach cancer, the cancer has spread to distant organs (such as the lungs or liver) and/or far away lymph nodes and/or the tissue that lines the abdominal wall.

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Common types of treatment

Once your doctor has confirmed your cancer diagnosis and performed the necessary tests, including for biomarkers, they will work with you to determine which treatment plan is right for you. Your doctor may recommend one or more of the following treatments:

  • Chemoradiation: A combination of chemotherapy and radiation to increase the effects of both
  • Chemotherapy: The use of drugs to stop cancer cell growth
  • Immunotherapy: A treatment using the patient’s immune system to fight cancer 
  • Radiation therapy: The use of x-rays or other types of radiation to kill cancer cells or keep them from growing
  • Surgery: Removing the affected tissue
  • Targeted therapy: The use of drugs or other substances to identify and attack specific cancer cells

Visit Common cancer treatments for more information.

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Example questions to ask your doctor

  • What kind of stomach cancer do I have?
  • What is the stage of my cancer, and what does that mean in my case?
  • Was my cancer tested for biomarkers?
  • What do my biomarker testing results mean?
  • Based on what you’ve learned about my cancer, what is my prognosis (outlook)?
  • What treatment choices do I have?
  • What is the goal of treatment (to cure the cancer, slow its growth, ease symptoms, etc.)?
  • Should I get a second opinion?
  • If surgery is recommended, is there anything else I need to do or take before or after surgery?
  • How quickly do we need to decide on treatment?
        
What kind of stomach cancer do I have?
What is the stage of my cancer, and what does that mean in my case?
Was my cancer tested for biomarkers?
What do my biomarker testing results mean?
Based on what you’ve learned about my cancer, what is my prognosis (outlook)?
What treatment choices do I have?
What is the goal of treatment (to cure the cancer, slow its growth, ease symptoms, etc.)?
Should I get a second opinion?
If surgery is recommended, is there anything else I need to do or take before or after surgery?
How quickly do we need to decide on treatment?

Bring these questions to your next doctor’s visit: into your email or another document to print or save.

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What’s next

Tests that impact treatment options
Be involved in treatment decisions
Who Is on Your Cancer Care Team?
Who is on your care team

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