The lymphatic system is the complex network of vessels, lymph nodes, and other organs that helps the body fight infection and get rid of waste. Lymphoma usually starts in the lymphatic system. In some cases, however, lymphoma develops from lymphocytes (white blood cells) located in other tissues. Doctors refer to these cases of lymphoma as extranodal because they occur outside of the lymph nodes.
Primary gastric lymphoma is extranodal lymphoma that develops from lymphocytes in the stomach. It is different from secondary gastric lymphoma, which occurs when lymphoma develops in another location and spreads to the stomach.
About 30 percent to 40 percent of extranodal lymphomas are gastric lymphoma. Among all types of gastric cancer (cancer that occurs in the stomach), gastric lymphomas make up about 5 percent. Lymphoma of the stomach tends to affect people who are at least 50 years old, but the condition sometimes develops in teens. Men are two to three times more likely to develop gastric lymphoma than women.
The two main types of lymphoma are Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL). Each type develops from different cells in the immune system.
Extranodal NHL most often occurs in the stomach. Between 4 percent and 20 percent of extranodal non-Hodgkin lymphomas are gastric lymphoma. NHL can develop in either B cells or T cells but usually affects B cells.
There are several subtypes of NHL that may appear as gastric lymphoma. About 59 percent of gastric lymphoma cases are diffuse large B-cell lymphoma (DLBCL), a high-grade (fast-growing) cancer. Another 38 percent of cases are mucosa-associated lymphoid tissue (MALT) lymphoma, also called extranodal “marginal zone B-cell lymphoma.” MALT lymphoma is a low-grade (slow-growing) disease. Less often, gastric lymphoma is mantle cell lymphoma, follicular lymphoma, or peripheral T-cell lymphoma. The type of gastric lymphoma can influence a person’s treatment options and prognosis (outlook).
Gastric forms of HL are very rare, making up less than 1 percent of all gastric lymphoma cases. People with gastric lymphoma nearly always have NHL.
Some people with gastric lymphoma have no symptoms. Others have a wide range of symptoms that may overlap with symptoms seen in other stomach disorders.
Signs and symptoms of gastric lymphoma include:
About 3 out of 10 people with gastric lymphoma also experience B symptoms — fever, drenching night sweats, and unexpected weight loss. People may also have lymphadenopathy (swollen lymph nodes, which may appear as hard lumps under the skin).
Different types of gastric lymphoma have been linked to various risk factors.
Up to 9 out of 10 people with MALT lymphoma have a Helicobacter pylori infection. H. pylori is a bacteria that is often found in the stomach. It usually doesn’t lead to cancer. In some cases, however, this infection can cause ongoing stomach inflammation, which increases the numbers of lymphocytes in this organ. Eventually, these lymphocytes may turn cancerous. If MALT lymphoma is not treated, it may turn into gastric DLBCL. DLBCL can also develop on its own.
Gastric lymphoma is also sometimes linked to other types of infections. This type of cancer sometimes occurs in people who are infected with Campylobacter jejuni bacteria, Epstein-Barr virus, hepatitis B virus, or human T-cell leukemia virus type 1. Not everyone who is diagnosed with gastric lymphoma has a history of infection. Researchers are still studying the link between infection and lymphoma to better understand why some germs are cancer risk factors.
Gastric T-cell lymphomas have also been linked to celiac disease. This autoimmune condition develops when the body can’t properly process grains wheat, rye, and barley.
Doctors use several tests to diagnose gastric lymphoma. These may include:
If gastric lymphoma is diagnosed, additional tests may be used to help determine the lymphoma stage. The stage represents how far lymphoma cells have spread in the body and indicates how severe the disease is.
Basic blood tests can measure the levels of the three main types of blood cells: white blood cells, red blood cells, and platelets. Blood tests can also check levels of a protein called lactate dehydrogenase (LDH). People with lymphoma usually have increased levels of LDH, and very high levels often mean that the lymphoma is more aggressive.
Blood tests can also be used to check for infection by H. pylori or other bacteria or viruses. Infections may be diagnosed with breath tests or stool tests.
To better understand what is causing a stomach problem, doctors need to get a closer view. They usually do this with an upper endoscopy, also called an esophagogastroduodenoscopy. For this procedure, doctors use a thin tube with a camera on the end. They guide the tube through the throat to visualize the following tissues:
During an endoscopy, the doctor will usually perform a biopsy (remove a small piece of tissue). The biopsy sample can be further studied under a microscope to see whether cancer cells are present. If cells are cancerous, doctors can also perform laboratory tests on the biopsy sample to determine what type of cancer has developed.
After gastric lymphoma is diagnosed, doctors typically use additional imaging tests to learn more about how big the gastric tumor is. These tests can also show whether lymphoma cells have spread to nearby lymph nodes or organs.
Most often, CT scans are used to help stage gastric lymphoma. Often other imaging tests like positron emission tomography scans (or less commonly, MRI) are also needed.
Doctors usually use a version of the Lugano staging system to determine gastric lymphoma stages. Under this system, gastric lymphoma can’t be classified as stage 3. The stages used for gastric lymphoma are:
Gastric lymphoma treatment varies based on the lymphoma type, lymphoma stage, lymphoma grade, and whether the lymphoma is caused by an H. pylori infection. A person’s age, overall health, symptoms, and preferences also play a role in treatment decisions.
Slow-growing, early-stage MALT lymphoma is usually treated very easily. A person with this condition normally takes antibiotics to clear the H. pylori infection. Getting rid of the bacteria also gets rid of the lymphoma for most people.
It may take a long time — a year or more — for the lymphoma to disappear after antibiotic treatment. During this time, doctors often recommend a watch-and-wait approach, in which no further cancer treatment is given unless the cancer worsens. During this time, a person will undergo many follow-up doctor’s visits and tests to keep an eye on the cancer.
About 1 out of 10 cases of gastric MALT lymphoma don’t go away after the H. pylori infection is treated. Another 1 out of 10 people with this condition don’t have a bacterial infection in the first place. In these cases, other treatments may be needed:
DLBCL is a high-grade lymphoma that needs to be treated with more aggressive therapies. It is often treated with a chemotherapy regimen called R-CHOP, which consists of:
When gastric DLBCL is detected in the early stages, doctors may recommend radiation therapy after going through chemotherapy. People with advanced-stage gastric DLBCL usually only receive chemotherapy.
When gastric lymphoma is a form of HL, treatment usually begins with surgery. There is a chance that people with this condition also have lymphoma in other parts of the body outside the stomach. Therefore, doctors also generally recommend chemotherapy and radiation therapy after surgery.
A person’s prognosis after being diagnosed with gastric lymphoma depends on what type of lymphoma they have. People with MALT lymphoma usually have a very good outlook — after being diagnosed, 9 out of 10 people live for 10 years or more.
Gastric DLBCL is a faster-growing disease, and people with this condition may have a worse survival rate. About 53 percent of people with gastric DLBCL live for five years or more after diagnosis.
When a person has been diagnosed with gastric lymphoma, they are more likely to have a poor outlook if they have certain prognostic factors, including:
Those who have gastric Hodgkin lymphoma often have a poor prognosis. Between 45 percent and 60 percent of people with this condition die within one year after being diagnosed.
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