Stomach cancer—or gastric cancer—occurs when cells in the lining of the stomach wall mutate and grow uncontrollably.

The stomach wall has five layers, and different types of stomach cancer are often classified based on where they begin.

Each year, stomach cancer makes up about 1.5% of cancers in the United States. Knowing the types of stomach cancer can help you to recognize early symptoms and find the right treatment plan if needed. 

About 90-95% of stomach cancers are adenocarcinomas. These cancers develop in the innermost lining of the stomach, where the stomach makes digestive fluids.

Healthcare providers may describe adenocarcinoma based on the cancer’s cell type or the area of the stomach where the cancer cells are present.

Types of adenocarcinoma based on cell type include:

• Intestinal adenocarcinoma: The cancer cells look similar to normal cells under a microscope. This type usually has a better prognosis (outlook). 
• Diffuse adenocarcinoma: The cancer cells look different from normal cells under a microscope. This type tends to be more aggressive. 

Types of adenocarcinoma based on location in the stomach include:

• Gastric cardia cancer: This cancer develops where the stomach meets the esophagus in the top inch of the stomach, called the cardia. 
• Noncardia gastric cancer: This cancer develops in any other area of the stomach.

A rare type of adenocarcinoma that occurs in the stomach is called hereditary diffuse gastric cancer (HDGC). It may make up only 1-3% of all stomach cancers. An inherited gene mutation causes this type, which also increases the risk of breast cancer.

Symptoms

Symptoms of stomach adenocarcinomas may include:

• Stomach discomfort or indigestion
• A full or bloated feeling after eating
• Heartburn
• Nausea
• Appetite loss

Gastrointestinal stromal tumors (GISTs) are uncommon tumors that can develop in nerve cells anywhere in the digestive tract. They are most likely to form in specific cells—called interstitial cells of Cajal—in the stomach’s lining. GISTs are most likely to affect people over age 60. 

Symptoms

GISTs commonly cause gastrointestinal bleeding (bleeding in the digestive tract). This may cause symptoms such as:

• Anemia (low red blood cell counts)
• Vomiting blood or what looks like coffee grounds
• Black or bloody stools
• Weight loss

Gastrointestinal neuroendocrine tumors are cancerous tumors that begin in the stomach’s neuroendocrine cells. These cells share characteristics of nerve cells and endocrine (hormone-producing) cells. They produce hormones that control the function of the digestive juices and stomach muscles. 

Symptoms

Gastrointestinal neuroendocrine tumors often cause no symptoms in the early stages. If the cancer grows or spreads, it may cause carcinoid syndrome, with symptoms such as:

• Skin flushing (reddening or change in color of the skin)
• Stomach pain
• Diarrhea
• Breathing trouble
• Blood pressure changes
• Heart palpitations (fluttering, pounding, or skipping beats)

Gastric lymphoma is a rare type of stomach cancer that starts in the lymphocytes, a white blood cell in your immune system. It makes up about 5% of stomach cancers. This cancer is a type of non-Hodgkin lymphoma that forms in the stomach. It occurs when the immune system attacks the stomach tissues.

People with a history of Helicobacter pylori (H. pylori) infection may be at increased risk.

Symptoms

Symptoms of gastric lymphoma are usually similar to those of adenocarcinomas. These may include:

• Stomach discomfort or indigestion
• A full or bloated feeling after eating
• Heartburn
• Nausea
• Appetite loss

Less commonly, this type of stomach cancer may also cause:

• Fever
• Night sweats
• Weight loss

Other types of cancer that very rarely develop in the stomach include:

• Squamous cell carcinoma: This makes up less than 1% of all stomach cancers. Symptoms may include abdominal pain, weight loss, and dark, sticky stools.
• Sarcomatoid carcinoma: This is a very rare, very aggressive stomach cancer that forms in the stomach wall. The tumors can quickly grow and spread to nearby lymph nodes (small organs that are part of your immune system), making the cancer difficult to treat.
• Small cell carcinoma: This cancer causes similar symptoms to other stomach cancers. It spreads quickly to nearby lymph nodes and is difficult to treat.
• Leiomyosarcoma: This is a cancer that starts in smooth muscle. It’s extremely rare in the stomach. Possible symptoms include abdominal pain, diarrhea, bloody stool, and weight loss.

An oncologist (a medical doctor specializing in diagnosing and treating cancer) can help diagnose stomach cancer and its type. They will need to do diagnostic testing, which may include:

• History and physical: This involves asking for a detailed family history and performing a physical exam to look for signs of cancer.
• Blood tests: These may include a complete blood count (CBC) to look for low red blood cell counts.
• Stool test: Your oncologist may want to check for blood in your stool.
• Upper endoscopy with biopsy: This test allows your doctor to see the lining of your esophagus (the tube connecting your mouth to your stomach) and stomach to look for tumors or unusual cells. Your healthcare provider may also take a biopsy (tissue sample) and send it to the lab to look for cancer cells.
• Computed tomography (CT) scan: This imaging test uses multiple X-rays to create images of the inside of your body. It can help healthcare providers look for tumors in your stomach.

See your healthcare provider as soon as you develop any possible symptoms of stomach cancer. Stomach cancer does not usually cause symptoms in the early stages. Still, some symptoms that signal it’s time to see your healthcare provider include weight loss, nausea, or stomach pain that is unrelated to any other cause.

If a healthcare provider diagnoses you with stomach cancer, they may recommend cancer treatments such as chemotherapy, radiation therapy, surgery, or targeted therapy.

There is no proven way to prevent stomach cancer, but some strategies may help lower your risk. These include:

• Maintain a weight that you and your healthcare provider agree is appropriate for you
• Keep up with regular physical activity per your healthcare provider’s recommendations
• Eat a nutrient-rich diet, including fresh fruits and vegetables; citrus fruits may be particularly helpful 
• Avoid processed meats, sugary beverages, and heavily processed foods.
• Limit or cut out your alcohol use
• Avoid or quit smoking
• See your healthcare provider if you are concerned you could have an H. pylori infection
• Talk to your healthcare provider about genetic testing if anyone in your family has hereditary diffuse gastric cancer.

Stomach cancer is a type of cancer that starts in the stomach wall. Adenocarcinomas are the most common type, making up about 90-95% of cases in the U.S.

Stomach cancer does not usually cause symptoms in the early stages. See your healthcare provider if you have possible symptoms, including abdominal discomfort, indigestion, heartburn, and appetite loss.