Lymphoma is the most common type of blood cancer. Specifically, lymphoma is a cancer that affects lymphocytes, which are a type of white blood cell. Lymphocytes travel through the blood and lymphatic system to defend the body against foreign invaders like bacteria and viruses. Lymphomas usually develop when a change, or mutation, occurs within a lymphocyte, causing the abnormal cell to replicate faster than, or live longer than, a normal lymphocyte. Like normal lymphocytes, cancerous lymphocytes can travel through the blood and lymphatic system and spread and grow in many parts of the body, including the lymph nodes, spleen, bone marrow, and other organs.
Three major categories of cancers that affect lymphocytes are:
Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma (CLL/SLL): CLL/SLL are the same disease with slightly different manifestations. Where the cancerous cells gather determines whether it is called CLL or SLL. Leukemic cells develop because of a change that takes place in the cell’s DNA. Approximately 19,000 people are diagnosed with CLL/SLL in the United States each year.
Hodgkin Lymphoma (HL): There are five types of HL, an uncommon form of lymphoma that involves the Reed-Sternberg cells. Approximately 9,000 people are diagnosed with HL in the United States each year.
Non-Hodgkin Lymphoma (NHL): There are more than 90 types of NHL, some of which are more common than others. Any lymphoma that does not involve Reed-Sternberg cells is classified as non-Hodgkin lymphoma. Approximately 80,000 people are diagnosed with NHL each year in the United States.
Signs and Symptoms
Certain symptoms are not specific to lymphoma and are, in fact, similar to those of many other illnesses. People often first go to the doctor because they think they have a cold, the flu or some other respiratory infection that does not go away.
Common symptoms include:
- Swelling of lymph nodes, which may or may not be painless
- Unexplained weight loss
- Sweating (often at night)
- Lack of energy
Most people who have these non-specific symptoms will not have lymphoma. However, it is important that anyone with persistent symptoms be examined by a doctor to make sure lymphoma is not present.