Non-Hodgkin's lymphoma (NHL) is the third most common form of childhood cancer. About 56,800 cases of the disease were diagnosed in the United States in 1999; about 3 percent of these were in children younger than 16. Most cases occur in children ages 7 to 11. Boys are three times as likely to develop the disease than girls.
More than 90 percent of children with NHL are disease-free five years after being diagnosed. The five-year survival rate for children with more advanced stages is about 75 percent.
The lymphatic system is part of the body’s immune system. It helps the body fight disease and infection.
The lymphatic system includes a network of thin tubes that branch, like blood vessels, into tissues throughout the body. Lymphatic vessels carry lymph, which is a colorless, watery fluid that contains infection-fighting cells called lymphocytes.
These vessels connect lymph nodes, which are found in clusters in the underarms, groin, neck, chest and abdomen. Lymph nodes produce and store lymphocytes.
In non-Hodgkin’s lymphoma, lymphocytes become abnormal, divide and grow out of control. Old cells do not die as they normally should.
The two main types of lymphocytes are B-lymphocytes (or B-cells), which make antibodies; and T-lymphocytes (or T-cells), which kill viruses and foreign cells and "trigger" B-cells to make antibodies.
Both types of cells can develop into lymphomas in children. The disease can be present in one lymph node or in several lymph nodes. It can start almost anywhere in the body and can spread to almost any organ or tissue, including the liver, bone marrow and spleen.
The subtype of non-Hodgkin's is determined by how the cancer cells look under a microscope.
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