This page was reviewed under our medical and editorial policy by
Maurie Markman, MD, President, Medicine & Science
This page was updated on May 23, 2022.
Stomach cancer happens when cells start behaving abnormally, growing and proliferating uncontrollably. The stomach, a hollow organ that collects food and breaks it down, has five different parts—from the top of the stomach, which connects to the esophagus, to the bottom of the stomach, which connects to the small intestine:
There are also five layers of tissue and muscle that surround the stomach and make up the stomach wall. Going from inner to outer, the layers are:
Stomach cancer progressively spreads through these different layers. Establishing how far within the stomach wall the cancer has spread is a part of the staging process, which determines how serious the cancer is and how best to treat it.
The mucosa layer, which produces stomach acid, is where most stomach cancers begin.
A less common type of stomach cancer is caused by gastrointestinal stromal tumors (GISTs), which start in immature cells called interstitial cells of Cajal.
Other rare stomach cancer types, such as lymphoma and neuroendocrine tumors, start in different cell types in the stomach.
Different types of stomach cancer include:
Adenocarcinomas of the stomach develop in the cells of the innermost lining. Most stomach cancer cases, about 90 percent to 95 percent, are adenocarcinomas, according to the American Cancer Society (ACS).
Adenocarcinomas are broken down into two categories:
Linitis plastica is a rare subtype of adenocarcinoma of the stomach, accounting for 7 percent to 14 percent of cases, according to a study in the Annals of Surgical Oncology. In this type, the cancer cells spread throughout the stomach, causing tissues to stiffen. By the time it’s diagnosed, linitis plastica cancer has usually spread to lymph nodes. Compared with other types of adenocarcinomas, it tends to be difficult to treat.
Early-stage adenocarcinomas may come with symptoms such as:
As these cancers advance, they may cause:
Various tests may be used to diagnose these cancers, including:
Treatment options include:
Lymphomas are cancers of the immune system tissue that may start anywhere lymph tissues are found, including in the stomach. However, lymphomas in the stomach are rare, accounting for about 4 percent of all stomach cancers.
MALT (mucosa-associated lymphoid tissue) lymphoma is a type of non-Hodgkin lymphoma that typically occurs in the stomach. The cancer starts in lymph tissue that lines the stomach.
Most people who develop MALT lymphoma of the stomach have had a bacterial infection, especially one caused by helicobacter pylori (H. pylori), or a viral infection. This cancer tends to be slow-growing (though it’s been known to change to a fast-growing type), and is usually detected in the early stages. If it’s caused by an H. pylori infection, the cancer is often treated with antibiotics.
If the cancer doesn’t respond to antibiotics, other treatment options include:
Gastrointestinal stromal tumors, or GISTs, are a rare type of stomach cancer that forms in a special cell found in the lining of the stomach called interstitial cells of Cajal (ICCs). Under a microscope, GIST cells look similar to muscle or nerve cells. These tumors may develop throughout the digestive tract, but 60 percent to 70 percent occur in the stomach. In the United States, 4,000 to 6,000 new GIST cases throughout the GI tract are diagnosed per year, according to the ACS.
GISTs in the stomach may cause:
These tumors may also bleed, which causes blood to show up in vomit and bowel movements. Large tumors may cause a blockage between the stomach and intestine, leading to stomach pain and vomiting. These symptoms often lead people to see their doctor.
Diagnosis may involve:
Surgery and targeted therapy are the most commonly used treatment options for GISTs, but chemotherapy and radiation therapy may also be used.
Carcinoid tumors typically start in the hormone-producing cells of the stomach. These tumors usually don’t spread to different organs and account for about 3 percent of stomach cancer incidence.
The three types of gastric carcinoid tumors are:
About 8,000 gastrointestinal carcinoid tumors are diagnosed in the United States each year, according to the ACS. Not all of these cancers start in the stomach—they may also occur in the intestines, appendix, colon and rectum.
Carcinoid tumors of the stomach and digestive system may be diagnosed using imaging tests (such as X-rays, CT scans and MRI scans) and a biopsy. Gastrointestinal tumors may be biopsied during an endoscopy or by needle biopsy (a procedure using a needle to remove a small sample of the suspicious tissue, which is analyzed to see whether it contains cancer and determine the type of tumor).
Treatment options include:
Hereditary (familial) diffuse gastric cancer: About 1 percent to 3 percent of all stomach cancers are a rare type called hereditary diffuse gastric cancer (HDGC), according to the National Cancer Institute. This type of stomach cancer, which is caused by a genetic condition passed down from parents to children, tends to grow in multiple parts of the stomach and quickly spread to other areas of the body. Genetic testing reveals whether someone has a mutation associated with HDGC. These tests are recommended for people with two or more close relatives who developed stomach cancer at an early age or who were diagnosed with this particular type of stomach cancer.
Symptoms of this stomach cancer type may include:
It’s usually diagnosed using a needle biopsy. Imaging tests such as ultrasounds, CT scans and positron emission tomography (PET) scans may also be used to assess the tumor's size, location and spread in the body.
Treatment options include: