Stomach cancer occurs when cancerous cells grow within the lining of the stomach. This type of cancer is also called gastric cancer, and it can be difficult to diagnose because most people typically don’t show symptoms in the earlier stages. As a result, it often goes undiagnosed until after it spreads to other parts of the body.

According to the National Cancer Institute (NCI), there were an estimated 27,000 new cases of stomach cancer in 2021. The NCI also estimated that stomach cancer made up 1.4 percent of new cancer cases in the United States.

Even though stomach cancer can be hard to diagnose and treat, it’s important to get the knowledge you need to manage the disease.

Your stomach (along with the esophagus) is just one part of the upper section of your digestive tract. Your stomach is responsible for digesting food and then moving the nutrients along to the rest of your digestive organs, namely the small and large intestines.

Stomach cancer occurs when normally healthy cells within the upper digestive system become cancerous and grow out of control, forming a tumor. This process generally happens slowly. Usually, stomach cancer develops over many years.

There are several factors that might increase your risk of developing cancerous cells in your stomach. These risk factors include certain diseases and conditions, such as:

  • H. pylori bacterial infections (a common stomach infection that can sometimes lead to ulcers)
  • tumors in other parts of the digestive system
  • stomach polyps (abnormal growths of tissue that form on the lining of the stomach)
  • inherited genetic syndromes, such as Lynch syndrome and Li-Fraumeni syndrome

Stomach cancer is also more common among:

  • older adults, usually people in their 60s and older
  • men
  • people who smoke
  • people who are overweight or with obesity
  • people with a family history of the disease
  • people who are of Asian (especially Korean or Japanese), South American, or Eastern European descent

While your personal medical history can impact your risk of developing stomach cancer, certain lifestyle factors can also play a role. You may be more likely to get stomach cancer if you:

You may want to consider getting a screening test if you believe you’re at risk of developing stomach cancer. Screening tests are performed when people are at risk of certain diseases but don’t show symptoms yet.

According to the American Cancer Society, there are typically no early signs or symptoms of stomach cancer. This means that people often don’t know anything is wrong until the cancer has reached an advanced stage.

In some cases, there may be symptoms of the disease. Some of the most common symptoms of stomach cancer are:

Many of these symptoms are common in other conditions, such as an ulcer or an infection. This can make stomach cancer difficult to diagnose. If you have possible symptoms of stomach cancer that don’t get better, it’s important to see a doctor.

When cancer spreads, the process is called metastasis. Advanced or metastatic stomach cancer symptoms may include:

Stomach cancer symptoms in women tend to be similar to those in men, but the condition is more common in men. Symptoms in children may include constipation or diarrhea, but otherwise are the same as for adults.

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Since people with stomach cancer rarely show symptoms in the early stages, the disease is often not diagnosed until it’s more advanced.

Diagnosing stomach cancer involves receiving a physical exam to check for any abnormalities. A doctor may also look for possible bleeding in the stomach by using a test to check for blood in your stool along with a blood test to look for anemia.

More diagnostic tests for stomach cancer may need to be done if your doctor believes you show signs of the disease. Diagnostic tests specifically look for suspected tumors and other abnormalities in the stomach and esophagus. These tests may include:

The stage of stomach cancer indicates how far the cancer has spread in the body.

Usually, the TNM system from the American Joint Committee on Cancer is used to determine the stage of stomach cancer. The system looks at three areas:

  • T category: the size of the tumor and how far it extends
  • N category: how far the cancer has spread into the lymph nodes
  • M category: whether the cancer has spread to distant areas of the body

The findings in each category are combined to determine a stage of 0 to 4. A lower number represents an earlier stage of cancer. While tumor growth and spread will vary, in general, each stage looks like:

  • Stage 0. There are abnormal or cancerous cells in only the surface of the stomach lining, but the cancer hasn’t spread to the lymph nodes or other parts of the body.
  • Stage 1. The tumor has extended into deeper layers of the stomach. The cancer may or may not have spread to one or two of the lymph nodes surrounding the stomach, but it hasn’t spread to other parts of the body.
  • Stage 2. The tumor has reached deeper layers of the stomach, and the cancer has usually spread to the lymph nodes. It hasn’t spread to other parts of the body.
  • Stage 3. The tumor has grown deeper into the layers of the stomach and possibly into nearby organs. The cancer has likely spread to the lymph nodes, but hasn’t reached distant parts of the body.
  • Stage 4. The cancer may have reached deeper stomach layers or nearby lymph nodes, but this isn’t a requirement. At this stage, the cancer has spread to distant parts of the body such as the lungs, brain, or liver.

As long as the cancer hasn’t spread to distant parts of the body, it will be between stage 0 and 3. If it has spread to other areas, the diagnosis will be stage 4 stomach cancer.

Different stages have different treatments and expected survival rates. With early stage cancer that’s only in the stomach, there’s a 69.9 percent of surviving 5 years after diagnosis. For later stage cancer that’s reached distant areas of the body, the 5-year chance of survival drops to 5.5 percent.

Stomach cancer is usually treated with one or more of the following:

Your exact treatment plan will depend on the origin and stage of the cancer. Age and overall health can also play a role.

Aside from treating cancer cells in the stomach, the goal of treatment is to prevent the cells from spreading. Stomach cancer, when left untreated, may spread to the:

Stomach cancer alone can’t be prevented. However, you can lower your risk of developing all cancers by:

In some cases, doctors may prescribe medications that can help lower the risk of stomach cancer. This is usually done for people who have a precancerous condition or have other diseases that also benefit from the medication.

You may also want to consider getting an early screening test. This test can be helpful in identifying stomach cancer. A doctor may check for signs of the disease by using one of the following stomach cancer screening tests:

  • physical exam
  • lab tests, such as blood and urine tests
  • imaging procedures, such as X-rays
  • an endoscopy, where a tube with a lens is routed down your throat to look for abnormal areas
  • genetic tests

Your chances of recovery are better if the diagnosis is made in the early stages of stomach cancer. According to the NCI, around 32 percent of all people with stomach cancer are expected to survive at least 5 years after getting a diagnosis.

Most of these survivors have a localized diagnosis. This means that the stomach was the original source of the cancer and it hasn’t spread. When the origin is unknown, it can be difficult to diagnose and stage the cancer. This makes the cancer harder to treat.

It’s also more difficult to treat stomach cancer once it reaches the later stages. If your cancer is more advanced, you may want to consider participating in a clinical trial.

Clinical trials help determine whether a new medical procedure, device, or other treatment is effective for treating certain diseases and conditions. You can see if there are any clinical trials of treatments for stomach cancer on the NCI website.

The website also has resources to help you and your loved ones cope with a stomach cancer diagnosis and its subsequent treatment.