Overview of marrow transplantation.

Bone marrow transplantation is now an accepted form of therapy for many hematologic disorders including aplastic anemia, genetically determined diseases and malignant diseases, particularly leukemia, and for rescue of patients given intensive chemoradiotherapy for malignant disease. The donor may be a healthy identical twin, a family member or even an unrelated person. Selection is made on the basis of human leukocyte antigen tissue typing. Intensive chemoradiotherapy is used to suppress patients' immune systems to facilitate engraftment and destroy diseased marrow. Transfusion of platelets, erythrocytes and granulocytes (or all of these), antibiotic coverage and protection from infection are necessary during the pancytopenic period. Use of a Hickman catheter facilitates maintenance of adequate nutritional intake and provides easy access for drawing blood and intravenous administration. Survival rates vary considerably depending on a patient's disease, clinical state and age. Patients with aplastic anemia transplanted early in the course of their disease have a survival rate of approximately 80%. Patients with acute lymphoblastic leukemia are usually transplanted in a second or subsequent remission and have a survival rate of 25% to 40%. Patients with acute nonlymphoblastic leukemia in remission have survivals ranging from 45% to 70%. More than 200 patients in the chronic phase of chronic granulocytic leukemia have been transplanted with survival ranging from 50% to 70%. Complications of marrow transplantation include marrow graft rejection, graft-versus-host disease, immunologic insufficiency and the possibility of recurrence of the leukemia. The risk of death from these complications must be balanced against the possibility of cure.