What is Non-Hodgkin Lymphoma?
There are 2 main types of lymphoma: Hodgkin lymphoma and non-Hodgkin lymphoma. Non-Hodgkin lymphoma (NHL) is a type of blood cancer that starts in the white blood cells known as lymphocytes. NHL develops in the lymphatic system, part of the immune system that carries lymph fluid throughout the body. Because the lymphatic system is so widespread, NHL can begin in many different places in the body.1,2
There are also many subtypes of NHL, which are generally classed as indolent (slower growing) or aggressive (faster growing). The exact subtype is important to know to help guide treatment decisions.1,2
Non-Hodgkin lymphoma is one of the more common cancers in the U.S.1
What causes non-Hodgkin lymphoma?
Researchers do not know the exact cause of NHL, but they know that cancers like NHL begin with changes (mutations) to the DNA of the cells. Mutations to the DNA may be inherited, but inherited mutations typically do not seem to be involved in NHL. Having a family member with NHL does not appear to increase a person's risk of the disease, and NHL does not seem to run in families. The DNA mutations that occur in NHL may be spontaneous or as a result from exposure to certain environmental factors.1
How does it develop?
NHL can develop when mutations occur in lymphocytes, a type of white blood cell. There are two main types of lymphocytes, B lymphocytes (or B cells) and T lymphocytes (or T cells). NHL may develop from either type of lymphocyte, although it is more often seen in B cells.1
The lymphocytes collect in the lymph system, which is made up of lymphatic vessels, lymph nodes, collecting ducts, and several organs, including the spleen, thymus, and tonsils.3 Different types of NHL can begin in different parts of the lymph system.1
What are the different types?
There are more than 60 types of NHL.4 NHL is definted by:
- Which type of lymphocyte they develop from (B cell or T cell)
- How the cells look under a microscope
- The chromosomal features of the cells
- The types of proteins found on the surface of the cells
- How slowly or quickly the cells replicate or grow1,2
About 90 percent of all NHL cases are B-cell lymphomas. Some of the more well-known types of B-cell NHL are:
- Diffuse large B-cell lymphoma (DLBCL)
- Follicular lymphoma
- Chronic lymphocytic leukemia (CLL)/Small lymphocytic lymphoma (SLL)
- Mantle cell lymphoma (MCL)
- Marginal zone lymphomas
- Burkitt lymphoma
- Hairy cell leukemia (may be a lymphoma subtype)
- Waldenstrom macroglobulinemia
- Primary central nervous system lymphoma
- Primary eye (intraocular) lymphoma1,4
Roughly 10 percent of all NHL cases are T-cell lymphomas. Some of the more well-known types of T-cell NHL are:
- Precursor T-lymphoblastic lymphoma
- Cutaneous T-cell lymphoma (including mycosis fungoides and Sézary syndrome)
- Adult T-cell leukemia/lymphoma1,4
Different NHL subtypes are generally classed as either indolent (slower growing) or aggressive (faster growing). Aggressive lymphomas account for about 60 percent of all NHL, with the most common type of aggressive lymphoma being DLBCL. The most common type of indolent NHL is follicular lymphoma.2
How quickly the cancer grows helps determine the way it will be treated. For some types of indolent NHL, doctors may recommend watching and waiting. Other indolent types or aggressive types of NHL may require more intensive treatment.2
Who gets it?
NHL can potentially occur at any age. It is one of the more common cancers seen in children and teenagers. The risk of developing NHL increases with age. More than half of people with NHL are diagnosed at age 65 or older. It is more common in men than women.1
What increases the risk of developing non-Hodgkin lymphoma?
Risk factors that may increase a person's chances of developing NHL include:
- Having an immune deficiency, which may be due to an inherited condition, having human immunodeficiency virus (HIV), or due to medications like those used for organ transplants.
- Having an autoimmune disease
- Having certain chronic infections, including the Epstein-Barr virus (mononucleosis), hepatitis C, and the bacterium Helicobacter pylori (H pylori)1,2
People living in farm communities have a higher rate of NHL, leading some researchers to think herbicides and pesticides may be potential risk factors. More research is needed to find the association between these chemicals and the development of lymphoma.2
What are the common symptoms?
The symptoms of NHL may be different depending on the subtype of lymphoma and where it begins in the body. Some common symptoms of NHL include:
- Enlarged, painless lymph nodes
- Unexplained fevers
- Night sweats
- Unexpected weight loss
- Abdominal pain or a feeling of fullness (due to the spleen or liver being enlarged)
- Chest pain or shortness of breath1,2
How is it staged?
Non-Hodgkin lymphoma may be classified as Stage I, II, III, or IV. The staging may be further rated as A, B, or E.
- A is defined as no symptoms.
- B is defined as experiencing symptoms fever, weight loss, or night sweats.
- E is defined as cancer found outside of the lymph system.1,2
What is the prognosis?
Survival rates for all types of blood cancer have been improving as new treatments become available. Survival rates are based on previous outcomes of people who survive a set amount of time after diagnosis. In cancer estimates, experts use the "5-year survival rate" as a marker. However, it is important to remember that many people live more than 5 years after diagnosis and the statistics may not predict your unique case.
Based on data from 2009-2015, the National Cancer Institute has determined the 5-year survival rate for all cases of non-Hodgkin lymphoma is 72 percent, although the survival rates vary for each subtype of NHL.1,5