Lymphoma is cancer that develops in the lymphatic system.
The lymphatic system is part of the immune system, which defends the body against disease and infection. It is a network of vessels throughout the body, which carry a clear fluid called lymph. Organs including the spleen, thymus and bone marrow are also part of the lymphatic system.
Lymph is made of white blood cells called lymphocytes. These cells carry antibodies that destroy bacteria and viruses that make people sick. There are two types of lymphocytes, B-lymphocytes and T-lymphocytes. These cells protect the body from infections by producing antibodies and attacking organisms such as bacteria and viruses.
Lymphoma occurs when lymphocytes change and grow in an uncontrollable way and join to form a lump or tumour. The most common place for this to happen is in the lymph nodes, but it can also happen in other parts of the body.
There are more than 80 different sub-types of lymphoma, which are commonly grouped as either:
- Hodgkin lymphoma, or
- Non-Hodgkin lymphoma.
Types of lymphoma are also described according to whether they affect B-lymphocytes or T-lymphocytes, and whether they are slow growing (indolent) or fast growing (aggressive). Approximately 85% of lymphomas affect B-lymphocytes.