Current status of bone marrow transplantation in pediatric oncology

Histocompatible bone marrow transplantation (BMT) is the treatment of choice for pediatric patients with second remission acute lymphoblastic leukemia or acute myelogenous leukemia (AML) and has been successfully used to treat patients with first remission AML and stable-phase chronic myelogenous leukemia. The principle causes of transplantation failure are recurrent leukemia and therapeutic toxicities, including idiopathic interstitial pneumonitis and graft versus host disease (GVHD). The likelihood of leukemic relapse is related primarily to the remission status of the patient; patients in first remission have a lower relapse rate than patients in second remission, and the relapse rate of both is less than that of patients in relapse. Interstitial pneumonitis is due, in part, to the total body irradiation (TBI) that is used to cytoreduce the patients. TBI administration has been modified to reduce its toxicity. Acute and chronic GVHD are due to the immuno-aggression of donor T-lymphocytes against recipient non-HLA antigens. The in vitro removal of the T-lymphocytes from the donor bone marrow inoculum reduces the incidence of acute and chronic GVHD but may have the adverse effect of reducing hematopoietic engraftment and increasing leukemic relapse since the graft versus leukemia effect may be eliminated. The expanding role of BMT includes its use in the treatment of nonleukemic neoplasms (neuroblastoma, solid tumors) and the use of histoincompatible BMT for eligible patients without histocompatible donors.