Lymphomas are a common type of cancer. The condition can be categorized into two types: the more common non-Hodgkin's lymphoma and the less common Hodgkin's lymphoma. About 65,000 Americans will be diagnosed this year with lymphoma. Nearly all (about 57,000) of these people will be diagnosed as non-Hodgkin's lymphoma, whereas the rest will be diagnosed with Hodgkin's lymphoma. Most lymphomas occur in adults, with the average age at diagnosis between 60 and 70 for non-Hodgkin’s lymphomas.
Non-Hodgkin's lymphomas are cancers of lymphocytes (a type of white blood cell). Lymphocytes make up an important part of the immune system, which helps protect you from infections. To carry out their functions, lymphocytes are found throughout the body. They are primarily produced in the bone marrow and lymph nodes in adults, but also circulate in the blood and are found in other organs in the body. Thus lymphomas can originate at any site in the body.
There are several names for types of non-Hodgkin’s lymphomas, including lymphoblastic lymphoma, diffuse large B-cell lymphoma, peripheral T-cell lymphoma, follicular lymphoma, and Burkitt’s lymphoma. These and other names are used because non-Hodgkin’s lymphomas are a group of diseases—not just one condition. An accurate diagnosis of the specific type of lymphoma is important for receiving the best care.
The exact cause of most non-Hodgkin's lymphomas is not known. Exposure to certain chemicals used in farming can increase the risk of lymphoma. Patients with severe immune deficiencies are more likely to develop lymphoma as are patients with diseases of the immune system, such as rheumatoid arthritis. Research also indicates that infections by certain microorganisms, such as with the bacterium Helicobacter pylori, the human T-cell lymphoma virus-I (HTLV-1), or the human immunodeficiency virus (HIV), can also predispose individuals to developing lymphoma.