Cancer is when cells in the body change (mutate) and grow out of control. To help you understand what happens when you have cancer, let's look at how your body works normally. Your body is made up of tiny building blocks called cells. Normal cells grow when your body needs them, and die when your body doesn't need them any longer.
Cancer is made up of abnormal cells that grow even though your body doesn't need them. In most cancers, the abnormal cells grow to form a lump or mass called a tumor. If cancer cells are in your body long enough, they can grow into, or invade, nearby areas. They can even spread to other parts of your body. This is called metastasis.
Non-Hodgkin lymphoma is cancer that starts in the lymphatic (lymph) system. Certain cells in the lymph system, called lymphocytes, grow out of control. The lymphoma cells, or changed (mutated) lymphocytes, collect in the nodes and form a tumor. Sometimes tumors form in the spleen or in other lymph organs, like the thymus or tonsils.
The lymphatic system is part of the immune system. It's spread throughout the body and helps the body fight infection. It also helps maintain fluid balance in different parts of the body. The lymphatic system includes:
Lymphocytes. These are a type of white blood cell. They fight infection and disease.
Lymph. This is a clear fluid that contains lymphocytes.
Lymph vessels. These are tiny tubes. They carry lymph fluid from all over the body back to the bloodstream.
Lymph nodes. These are small organs about the size of a pea. They're found in the underarms, groin, neck, chest, belly (abdomen), and other parts of the body. They filter the lymph fluid as it moves through the body.
Other organs and body tissues. The lymphatic system includes the bone marrow where blood is made. It also includes the spleen, thymus, tonsils, and digestive tract.
There are 2 main kinds of lymphocytes:
B-lymphocytes (B-cells). B-cells fight germs like bacteria by making antibodies. These antibodies attach to the bacteria and attract other cells that fight the bacteria. The antibodies also attract proteins from the blood to help kill bacteria.
T-lymphocytes (T-cells). T-cells protect the body from fungi, viruses, and some bacteria. T-cells are able to find viral proteins in a virus-infected cell and then destroy the infected cell. T-cells also send out proteins called cytokines. These proteins signal other types of white blood cells to help fight the infection. T-cells can also kill some cancer cells.
Cancer that starts in B-cells, or B-cell lymphoma, is much more common than T-cell lymphoma. About 85 - 90% of people with non-Hodgkin lymphoma have B-cell lymphoma.
Lymphoma can start in any part of your lymphatic system. It can then spread to other parts of your body. Lymphoma may also spread to the bone marrow and to other organs. It can spread in different ways. It depends on the type of lymphoma and where it first started.
Lymphoma that starts in an organ that's not a lymph node, such as the stomach or spleen, is called extranodal lymphoma.
Non-Hodgkin lymphoma is not the same as Hodgkin lymphoma. With Hodgkin lymphoma, cancer cells only make up a small part of the cells in a cancerous lymph node. The rest of the cells are normal immune cells. The cancer cells are usually special cells called Reed-Sternberg cells. In non-Hodgkin lymphoma, cancer cells make up most of a tumor, and there are no Reed-Sternberg cells in it.
Hodgkin and non-Hodgkin lymphoma also differ in the way they spread and in how they are treated.
Lymphomas can be grouped in different ways. They can be grouped by the type of lymphocytes they start in: B-cells or T-cells. Another way to group them is based on how fast they grow, such as:
Indolent (low-grade) lymphoma. These types tend to grow slowly. They tend to cause few symptoms, at least at first. These lymphomas may not need to be treated right away. And they often respond well to treatment, so people with this type can often live for a long time. But these lymphomas tend to be much harder to cure than faster-growing lymphomas.
Aggressive (high-grade) lymphoma. These types tend to grow and spread quickly. They usually need to be treated right away. Even though they grow quickly, these lymphomas often respond well to treatment. Some of them may be curable.
There are many different types of non-Hodgkin lymphoma. They grow at different rates, and are treated in different ways. Finding out which type of non-Hodgkin lymphoma you have is very important in choosing the best treatment.
The common types of B-cell lymphoma include:
Diffuse large B-cell lymphoma (DLBCL). DLBCL makes up almost 1/3 of all lymphomas. It's a fast-growing or aggressive type of lymphoma. About 3 in 4 people have no signs of lymphoma after treatment, and many people with DLBCL can be cured. The outcome or prognosis is best for people with lymphoma in only one part of the body.
Follicular lymphoma. This type makes up about 1 in 5 lymphomas. It's an indolent or slow-growing type of lymphoma. Most of the time, it's found in many lymph nodes throughout the body and in the bone marrow. This lymphoma tends to grow slowly and often responds well to treatment. But it is hard to cure.
Chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). These related types are named based on where the lymphoma is found. CLL is mostly in the blood and bone marrow. SLL is mainly in the lymph nodes. Both are slow-growing diseases. These lymphomas are often not curable with standard types of treatment. But most people can live with these types of lymphoma for more than 10 years.
Extranodal marginal zone B-cell lymphomas or MALT lymphomas. Marginal zone lymphomas make up about 1 in 20 to 1 in 10 lymphomas. They start outside of the lymph nodes. Most start in the stomach, and are linked to an infection by Helicobacter pylori bacteria. MALT lymphomas can also start in the lungs, skin, thyroid, salivary glands, and the tissues around the eye. When it's in the stomach, this lymphoma can often be cured by giving antibiotics to kill the bacteria that cause it.
Mantle cell lymphoma. This type accounts for about 1 in 20 lymphomas. It's more common in men than women. In most cases it's widespread when diagnosed: in lymph nodes, bone marrow, and often the spleen. This lymphoma does not grow very fast. But it can be hard to treat.
Primary mediastinal B-cell lymphoma. This type accounts for about 1 in 50 lymphomas. It is a subtype of DLBCL. It's mostly found in young women. This lymphoma starts in the area around the heart and behind the chest bone, called the mediastinum. It's a fast-growing lymphoma, but it's treatable.
Burkitt lymphoma. This type is rare in adults. It's a lot like Burkitt-like lymphoma. Most people with this disease are male. This lymphoma grows very quickly. But more than half cured with aggressive chemotherapy.
Lymphoplasmacytic lymphoma or Waldenstrom macroglobulinemia. This is a rare, slow-growing type of lymphoma. It's found mainly in the bone marrow, lymph nodes, and spleen. People with this type usually live many years with the disease, but it's usually not curable.
Hairy cell leukemia. Despite its name, this is often considered to be a type of lymphoma. Only about 700 people in the U.S. are diagnosed with this type every year. It’s named for the hairy look of its cells. This lymphoma is typically found in the bone marrow, spleen, and blood. It tends to be slow growing and is often curable.
Primary central nervous system (CNS) lymphoma. This type usually grows in the brain. It may also be found in the spinal cord and the tissues around it, as well as in the eye. Over time, it becomes widespread in the central nervous system. This type of lymphoma is more common in people with immune system problems, such as AIDS.
The common types of T-cell lymphoma include:
Angioimmunoblastic T-cell lymphoma. This fast-growing type tends to occur in the lymph nodes, spleen, and liver. It causes infections, fever, weight loss, and skin rashes. It’s not clear if this lymphoma is curable. It tends to come back after treatment.
Extranodal natural killer/T-cell lymphoma, nasal type. This type often grows in the upper airway passages, such as the nose and upper throat. It can also grow into the skin and digestive tract. It's very rare in the U. S.
Enteropathy-type T-cell lymphoma. This type occurs in people with sensitivity to gluten, the main protein in wheat flour. Celiac disease, or gluten-sensitive enteropathy, that started in adulthood is linked with this type of lymphoma. It often grows into the walls of the intestines, and it can be hard to treat.
Anaplastic large cell lymphoma. About 1 in 100 to 1 in 50 lymphomas are this kind. It's a fast-growing type that's more common in young people. It starts in the lymph nodes and can also spread to the skin. Treatment with chemotherapy often works well.
T-lymphoblastic lymphoma/leukemia. This rare disease can be called lymphoma or leukemia. It depends on how much it’s growing in the bone marrow. Leukemia involves more bone marrow than lymphoma. About 1% of all lymphomas are this type. It often starts in the thymus, which is in the front part of the chest. People with this type are most often young men. The lymphoma is fast-growing. But the chance for a cure with chemotherapy is good if it hasn’t spread to the bone marrow when first diagnosed.
Cutaneous T-cell lymphoma (mycosis fungoides, Sezary syndrome). This starts in the skin. It accounts for about 1 in 20 lymphomas. It starts as a patchy, red rash. It can grow into solid, raised tumors that can grow into lymph nodes and organs, such as the liver and spleen. With Sezary syndrome, the lymphoma cells are found in the blood. The prognosis is better if the lymphoma hasn’t spread.
Peripheral T-cell lymphoma, not otherwise specified (NOS). This term is used to describe T-cell lymphoma that doesn’t fit in other categories. Most people with this type of lymphoma are in their 60s. It tends to grow quickly and be widespread.
If you have questions about non-Hodgkin lymphoma, talk with your healthcare provider. Your healthcare provider can help you understand more about this cancer.