Lymphoma

Lymphoma (or lymphatic cancer), is a broad term encompassing a variety of cancers of the lymphatic system. The two main groups of lymphoma in humans are Hodgkin lymphoma (HL), also known as Hodgkin disease, and the non-Hodgkin lymphoma (NHL).

Hodgkin lymphoma, named for Thomas Hodgkin, a British physician who identified it in 1832, is a rare cancer and accounts for only about 14 percent of all lymphomas and less than 1 percent of all cases of cancer in this country. In Hodgkin lymphoma, cells in the lymphatic system become abnormal. They divide too rapidly and grow without any order or control. Because lymphatic tissue is present in many parts of the body, Hodgkin lymphoma can start almost anywhere. Hodgkin lymphoma may occur in a single lymph node, a group of lymph nodes, or, sometimes, in other parts of the lymphatic system such as the bone marrow and spleen. This type of cancer tends to spread in a fairly orderly way from one group of lymph nodes to the next group. For example, Hodgkin lymphoma that arises in the lymph nodes in the neck spreads first to the nodes above the collarbones, and then to the lymph nodes under the arms and within the chest. Eventually, it can spread to almost any other part of the body (contiguous spread).

The other group, non-Hodgkin lymphoma, accounts for about 3 percent of all malignancies. In non-Hodgkin lymphoma, cells in the lymphatic system become abnormal. They divide and grow without any order or control, or old cells do not die as cells normally do. Because lymphatic tissue is present in many parts of the body, non-Hodgkin lymphoma can start almost anywhere in the body. Non-Hodgkin lymphoma may occur in a single lymph node, a group of lymph nodes, or in another organ. This type of cancer can spread to almost any part of the body, including the liver, bone marrow, and spleen (non-contiguous spread).

Risk Factors
Men develop NHL 30 percent more often than women. Eighty-five percent of childhood Hodgkin lymphoma cases are in males, as are all lymphoma histologies in adults except nodular sclerosing. HL (Hodgkin Lymphoma) peaks in the 20-29 age range and again in the 50+ range. The histologies for these two peaks are different. Caucasian children are at slightly greater risk than African-American children.

Others at risk are:


 * People with inherited immune deficiency diseases, such as chronic immunosuppression (for organ transplants), acquired immunosuppression, Klinefelter syndrome, Chediak-Higashi syndrome, lymphocytopenia, lymphoid infiltrates in the skin; malignant lymphoma, mycosis fungoides, Sezary's disease, malignant histiocytosis, Letter-Siwe's disease, multiple myeloma, plasmacytoma, any leukemia, Waldenstrom's macroglobulinemia.
 * People with autoimmune disease, such as rheumatoid arthritis or systemic lupus erythematosus.
 * People infected with HIV (particularly primary lymphoma of the brain).
 * People taking immunosuppressant drugs following organ transplant.
 * People who have received radiation therapy and/or chemotherapy.
 * People who work extensively with or are otherwise exposed to chemicals, such as pesticides or some fertilizers.
 * People who have persistent generalized lymphadenopathy, lymphatic disorders, including frequent lymphoid hyperplasia, chronic lymphadenopathy, infectious mononucleosis, exposure to Epstein-Barr virus.

Treatment
Current therapy for Hodgkin lymphoma cures over 75% of patients. However, NHL can convert to a more aggressive form after initial treatment. Standards of treatment are radiation therapy and combination chemotherapy.

Treatment for non-Hodgkin lymphoma depends on the cell type and stage at diagnosis. Treatment for both Hodgkin lymphoma and non-Hodgkin lymphoma is usually radiation therapy (for early stage disease, Stage I and II) and/or chemotherapy (for stage III and IV cases), but this may vary by cell type. For example, low grade, low stage non-Hodgkin lymphoma may be treated with radiation only, whereas intermediate grade, low stage NHL should receive radiation and chemotherapy, and high-grade, low stage NHL would probably receive chemotherapy only.

Low grade non-Hodgkin lymphomas respond to chemotherapy and irradiation, but continue to relapse for a long period of time. Choice of chemotherapy regiment depends on stage and cell type.

Radiation is commonly used in low stage Hodgkin lymphoma and non-Hodgkin lymphomas (Stage I and II). Patients with higher stage disease may be treated with radiation to reduce tumor mass or bulky disease. Usually patients are treated with radiation on only one side of the body (above or below the diaphragm). Radiation may also be given for central nervous system prophylaxis, or for intracranial metastases.