Radiotherapy in leukemia and lymphoma of children.

Radiotherapy is important in the treatment of leukemia and lymphoma of children. In acute lymphocytic leukemia administration of cranial irradiation early during chemotherapy-induced remission prevents initial meningeal relapse. When cranial irradiation is combined with a 3-year course of multiple drug systemic chemotherapy approximately one-half of the children remain in complete remission for 5 years or more and are at little risk of relapse. Preventive cranial irradiation is effective in children with acute myelocytic leukemia, also, but this does not affect survival because of the inadequacy of chemotherapy in controlling bone marrow disease. Low dose palliative irradiation can be helpful in caring for some children with obstructive, painful or disabling leukemic lesions. In Hodgkin's disease of children radiotherapy is effective in curing stages IA, IIA, and IIIA disease and contributes to chemotherapy control of stages IIIB and IV disease. The role of radiotherapy in non-Hodgkin's lymphoma is less clear. Children with T-lymphoblastic lymphoma tend to have rapid dissemination to bone marrow and meninges and appear to benefit more from multiple agent chemotherapy and preventive meningeal irradiation. Children with B-lymphoblastic lymphoma usually benefit from cyclophosphamide therapy; the value of irradiation is yet to be established. However, radiotherapy is frequently curative in stage I B-lymphocytic nodular and histiocytic lymphomas. The indications for radiotherapy in children with leukemia and lymphoma are constantly changing. Before each child is treated the multi disciplinary evaluation and treatment team must consider the rationale in relation to the specific child and current knowledge.