What is stomach cancer?

Cancerous cells, or cells that replicate abnormally, can develop in any part of your body, including your stomach. Stomach cancer, or gastric cancer, can often lead to weight loss, abdominal pain, swelling or discomfort, nausea and vomiting, and heartburn. Fortunately, through early detection and treatment stomach cancer is treatable in most cases.

When to See a Doctor

You should see a doctor if you have any of the symptoms of stomach cancer, or if you are at risk for developing this disease.

Diagnosis and Treatment


Stages of Stomach Cancer

Before moving forward with treatment, your oncologist and cancer team will determine what stage of stomach cancer you have. Through a series of diagnostic tests, scans, and examinations your doctor will measure:

  • The size and extent of the tumor (or mass of cancerous cells).
  • How many layers of the stomach are affected.
  • The number of lymph nodes that have become cancerous.
  • How far the cancer has spread. 

These factors are known as the TNM System, used throughout the country to classify the stages of stomach cancer. In some cases, your doctor may also recommend surgery to take a closer look at your individual stomach cancer, taking samples of tissue to analyze and interpret.

Each stage of cancer correlates to a Roman numeral, from 0 to IV, with IV being the most advanced and severe. Below is an overview of each stage of cancer according to the National Cancer Institute.

  • Stage 0: Also known as “carcinoma in situ,” the cancer is found only in the innermost layer of the stomach wall and has not spread anywhere else.
  • Stage I: The cancer is in the first two layers of the stomach and has spread to the lymph nodes closes to the tumor.
  • Stage II: The cancer is only in the second, third, or maybe fourth layer of the stomach, and has spread to a few lymph nodes near the tumor. Stomach cancer will also be classified as Stage II if the tumor has gone through the outer wall of the stomach but hasn’t spread to the lymph nodes or other organs.
  • Stage III: In Stage III, the cancer is in the outermost layer of the stomach wall, and has spread to one or two lymph nodes near the stomach. The cancer may also be in the third layer of the stomach wall while spreading to three or more lymph nodes. Stomach cancer is also classified as Stage III if the cancerous cells have spread through all five layers of the stomach and up to 15 lymph nodes.
  • Stage IV: The most serious of the stomach cancer stages, Stage IV indicates that the cancer has spread to other parts of the body besides the stomach and lymph nodes, including other vital organs.