What is lymphoma?
Lymphoma is an umbrella term describing dozens of cancers that begin in the immune system. Lymphomas are the most common type of blood cancer, and are broadly categorized as either Hodgkin or non-Hodgkin disease. All lymphoma subtypes combined are the seventh most common cancer in the United States.
This year, over 80,000 adults and children in the United States will be diagnosed with non-Hodgkin lymphoma and approximately 8,500 with Hodgkin lymphoma, according to the American Cancer Society.
About 90% of people with lymphoma are diagnosed with non-Hodgkin lymphoma.
Hodgkin lymphoma occurs when white blood cells called B-lymphocytes become abnormal and begin growing and dividing so fast that normal cells in the immune system cannot keep up. Hodgkin lymphoma cells are called Reed-Sternberg – large cells with more than one nucleus that resemble “owl’s eyes.” Hodgkin lymphoma is rarer than non-Hodgkin and is most common among young people.
Non-Hodgkin lymphoma occurs when either B or T cell lymphocytes become abnormal. In most cases it is the B cells that are defective. Non-Hodgkin lymphomas are categorized based on a spectrum of how they behave in the body:
- Indolent (low grade) develop slowly, over years. These cancers are considered chronic – treatable but not generally curable because they tend to come back even after successful treatment.
- Aggressive (intermediate grade) lymphomas grow quickly over the course of months and are treatable and potentially curable.
- Highly aggressive (high grade) lymphomas develop very quickly – within weeks – and are highly curable, especially with chemotherapy.
Hodgkin and non-Hodgkin tend to behave differently in the body and treatments for each disease differ.
How lymphoma develops
Lymphoma is not just one disease but a large, complex group of blood cancers that start in a part of the immune system called the lymphatic system. This system of tissues, organs and vessels is made up of pea-sized organs (called nodes) where white blood cells cluster, connected by thin tubes (called vessels). Because this system is so widespread, cancers involving the lymphatic system can begin in almost any body part.
An abnormal immune response
Lymphoma develops when lymphocytes – infection-fighting white blood cells in the immune system – become abnormal and grow and divide uncontrollably into tumors. Lymphocytes are the main part of the immune system and circulate throughout the body responding to bacteria and viruses.
With lymphoma, abnormal white blood cells grow in number (also causing the lymph nodes to swell) not because of an infection, but because of a defect inside the cells. Instead of fighting disease, these cells, which have no real purpose in the body, grow and take up space. In contrast to a normal immune response, with lymphoma, swelling in the lymph nodes does not subside.
What are the Types of lymphoma?
There are dozens of lymphoma types – all related, yet appearing and acting differently in the body. While lymphoma is a rare disease overall some types are more commonly diagnosed including:
- Diffuse large B cell lymphoma, the most common type of non-Hodgkin lymphoma, is a fast-growing cancer that tends to start in lymph nodes in the upper part of the body such as the chest, neck, abdomen or armpit.
- Follicular lymphoma, the second most common type of non-Hodgkin lymphoma, tends to start in lymph nodes throughout the body and the bone marrow. This typically slow-growing (indolent) disease can, over time, become a more aggressive type.
- Cutaneous T cell lymphomas involve the skin, and tend to start with rash, intense itching, dry skin, pain and enlarged lymph nodes. The most common CTCLs include mycosis fungoides and Sezary syndrome.
- Small cell lymphocytic lymphoma and chronic lymphocytic leukemia are the same disease but found in different areas of the body. SLL cells tend to be found in lymph nodes while CLL cells are in the blood and bone marrow.
- Marginal zone lymphomas
- Mucosa-associated lymphoid tissue lymphoma, or MALT, also called extranodal marginal zone lymphoma, develops outside the lymph nodes in organs like the stomach, thyroid, eyes, small intestine and lungs.
- Nodal marginal zone lymphoma occurs within the lymph nodes.
- Splenic marginal zone lymphomas develop in the spleen and blood and are associated with hepatitis C infection.
- Waldenstrom macroglobulinemia begins when the body produces too much of a protein called immunoglobulin, which thickens the blood. Waldenstrom cells may crowd out normal cells in bone marrow, like red and white blood cells and platelets.
- AIDS-related lymphoma develops in patients who have acquired immune deficiency syndrome. Patients with weakened immune systems are at significantly greater risk of lymphoma.
- Anaplastic large cell lymphoma is rare type of lymphoma that can appear in lymph nodes, organs within the body or the skin. Anaplastic large cell and cutaneous lymphomas are among several subtypes of peripheral T cell lymphoma.
- Burkitt lymphoma is one of the fastest-growing types of lymphoma affecting both adults and children. It is most often associated with Epstein-Barr virus infection but can occur in anyone who has a weakened immune system.
- Central nervous system lymphoma develops in lymph tissue located in the brain and spinal cord.
- Lymphoblastic lymphoma is a rare form of non-Hodgkin lymphoma, involving abnormal B or T cells, which most often affects children.
- Mantle cell lymphoma develops from cancerous cells in what is called the mantle zone (outer edge) of a lymph node. It can be fast- or slow-growing and may spread to the gastrointestinal tract and bone marrow.
- Composite lymphoma is a rare type that is composed of several different types of lymphoma cells.
What increases your risk of lymphoma?
Things that put you at higher risk for getting lymphoma are called risk factors. Doctors do not know what causes most lymphomas, and there is very little that can be done to avoid being diagnosed. For most patients, it is not one but a combination of factors that likely contributes to developing lymphoma. Risk factors for lymphoma include:
- Immune system problems, including having HIV/AIDS other autoimmune diseases and being on immune-suppressing medication, is the most recognized risk for lymphoma.
- Age increases the risk of most cancers, including lymphoma.
- Sex is a risk factor; males are more likely than females to be diagnosed.
- Race increases risk; Caucasians are more likely to develop lymphoma.
- Previous cancer treatment with chemotherapy and radiation can increase risk.
- Infections such as the Epstein-Barr virus, human T cell leukemia virus type 1 and human herpes virus-8 increase risk of certain lymphoma subtypes. Other infections such as chlamydia, helicobacter pylori and hepatitis C are also associated.
- Family history, such as having a brother, sister or parent with lymphoma, can slightly increase risk of certain lymphomas.
- Chemicals, pesticides and exposure to other toxins like Agent Orange and benzene may be linked to developing lymphoma.
- Obesity or being overweight is associated with developing several cancers and, in some studies, has shown an association with lymphoma.
What are the symptoms of Lymphoma?
Usually there are no early warning signs of lymphoma so it tends to be diagnosed during later stages. Some of the first signs of lymphoma are the same as other illnesses, including swollen lymph nodes, cough and fever, making it difficult to diagnose early-on. The most common symptoms of lymphoma include:
- Swollen lymph nodes (in the neck, armpits or groin) that do not go away
- Severe itching all over the body
- Excessive sweating, especially at night
- Unexplained weight loss
- Unusual tiredness or weakness that does not go away
- Abdominal discomfort, pain or fullness when eating (due to an enlarged spleen)
- Low red blood cell count
- Shortness of breath or persistent cough
- Chest pain or pressure
While swollen lymph nodes associated with lymphoma may first appear in any body part, swelling associated with Hodgkin lymphoma is more likely to start in the upper body, including the neck, chest and sometimes the abdomen.
Symptoms of other medical conditions may mirror those of lymphoma. If you are treated for those conditions, or if your symptoms last for several weeks despite medical treatment, you may need further consultation to rule out lymphoma.
Maintaining a healthy weight and diet has been shown in some studies to lower the risk of developing lymphoma. Studies have linked eating a diet rich in fruits and vegetables with substantially reduced risk of lymphoma and, as with many cancers, being physically active and not overconsuming products with animal fats may also help.