Prophylactic Radiotherapy in Acute Lymphocytics Leukemia of Children

The concept of CNS preventive therapy in childhood all is based on the assumption that undetectable CNS leukemia is present in most patients at the time of diagnosis, residing in that "sdnctuary site" protected by the blood-brain barrier from cytotoxic concentrations of most systemically ad­ministered antileukemic agents. Studies in the 1960s demonstrated that administration of 2400 rad cranial irradiation and intrathecal me thotrexate following systemic remission induc­tion reduced the incidence of overt CNS leukemia to, approximately 10% or less,which called CNS prophylaxis. There is now a large body of data that indicates that significant long-term side-effects, including impaired in - tellectual and psychomotor function, and neuro-endocrine dysfunction, may occur in patients treated with 2400 rad cranial irradiation. These findings have stimulated a search for alternative methods of CNS preventive therapy. It is now apparent that the risk of developing CNS leukemia varies in different patient depending upon a variety of predictive factors ( high initial WBC count, T-cell disease, thrombocytopenia, profound lymphadenopathy, or hepatosplenomegaly). Studies suggest that 1800 rad is as effective as 2400 rad, without sac - rificing control of CNS leukemia. So, for determination of the dose of irra­diation, we must look the age of the patient and the clinical features at presentation. Meanwhile, cranial irradiation and intrathecal methotrexate remain the best established way to prevent this chronic and distressing com­plication of childhood leukaemia.