Role of bone marrow transplantation in childhood lymphoblastic leukemia.

Allogeneic bone marrow transplantation is the only therapy introduced in the past 2 decades that has offered a better prognosis for children with ALL who have suffered a marrow relapse within 18 months of starting therapy. Currently, 40 to 50% of such patients are obtaining long remissions and are potentially cured by marrow transplantation. This therapy's effectiveness, however, is diminished by the problems of acute and chronic graft-versus-host disease, infection, and relapse. Further impact of marrow transplantation in the treatment of ALL awaits (1) more effective antileukemic preparative regimens or post-transplant antileukemic strategies, (2) less toxic preparative regimens to decrease the incidence of early and late effects, (3) more effective means of preventing and treating graft-versus-host disease, (4) the ability to safely perform mismatched marrow transplantation, and (5) more effective means of purging leukemic cells from remission bone marrow to expand the role of autologous marrow transplantation.