[Hematopoietic stem cell transplantation for treatment of acute leukemia]

Recently, hematopoietic stem cell transplantation has been diversified and classified into several types of transplants, including allogeneic bone marrow, peripheral blood stem cell and cord blood stem cell transplantation (BMT, PBSCT, CBSCT), from related or unrelated donors. In addition, autologous BMT or PBSCT can be used to facilitate hematologic reconstitution after marrow-ablative therapy for hematologic malignancies. At least 50% of patients with acute myeloblastic leukemia (AML) and acute lymphoblastic leukemia (ALL) can be cured by treatment with allogeneic BMT. Autologous BMT has been studied in comparison with allogeneic BMT or intensive chemotherapy in the treatment of AML and ALL. A series of large-scale prospective randomized studies have provided controversial results: relapse rates are significantly low, but treatment-related mortality is significantly high, after allogeneic or autologous BMT as compared to intensive chemotherapy. At present, it is somewhat difficult to determine which treatment modality is indicated as a postremission therapy for AML and ALL. Therefore, risk factors such as leukemia subtype, age, karyotype, and initial response should be taken into consideration when deciding on a postremission therapy. In the 1990's, the use of autologous PBSCT has been replacing autologous BMT, as autologous PBSCT has several advantages over autologous BMT. Consequently, allogeneic PBSCT has come to be increasingly used instead of allogeneic BMT in the treatment of leukemia. Recent clinical data clearly indicate that allogeneic PBSCT can be used as an alternative to allogeneic BMT. With well-designed clinical trials, the places, of allogeneic or autologous BMT and PBSCT will be clarified in the treatment strategy for acute leukemia.