Clusters of these lymph nodes are found in the underarm, groin, neck, and abdomen. A colorless, watery fluid, called lymph, which contains infection-fighting cells, moves through the system and is filtered by the nodes. Other parts of the lymph system are the spleen, thymus, tonsils, and bone marrow. Lymph tissue is also found in other parts of the body, including the stomach, intestines, and skin. Lymphomas, like other cancers, are diseases of the cells within the body.
Cancer involving lymph system cells causes cells to grow rapidly and without order.
This creates too many cells growing together forming tumors. Non-Hodgkin's lymphoma is the more common form and has about 10 different types. An estimated 64,000 new cases of lymphoma will be diagnosed in 1999, including 7,200 cases of Hodgkin's disease and 56,800 cases of non-Hodgkin's lymphoma. Since the early 1970's, incidence rates for non-Hodgkin's lymphoma have doubled, making it the second fastest rising cancers in the United States. Despite remarkable strides in understanding the biology of lymphomas, its causes remain unknown.