Stem cell transplantation for patients with myelodysplastic syndrome and secondary leukemias.

Most patients with myelodysplastic syndrome (MDS) are too old to be considered for intensive treatment, such as stem cell transplantation (SCT). Allogeneic SCT from an HLA-identical sibling donor is the curative treatment option for a relatively young patient (younger than 60 years) with MDS or secondary acute myeloid leukemia. Older age and lack of sibling donors limit this application. Alternative stem cell sources, such as unrelated donors, nonidentical family members, or autologous transplants, have been used more recently. Most patients may benefit optimally from an allogeneic SCT when the transplant is performed as soon as an HLA-identical family member has been identified. Progression to more advanced leukemia conditions will be associated with a higher failure rate due to increased relapse rate after SCT and higher treatment-related mortality. Delay of the transplant may be justified in a minority of patients with refractory anemia or refractory anemia with ringed sideroblasts without profound cytopenias or complex cytogenetic abnormalities and no need for erythrocyte transfusions. The present data from patients transplanted with sources of hematopoietic stem cells other than histocompatible sibling donors give an indication of the potential of other forms of transplantation. The disease-free survival of patients transplanted with histocompatible sibling donors was significantly better than the outcome of patients transplanted with other sources of stem cells. About one-third of the patients transplanted with stem cells from histocompatible siblings and about one-quarter of the patients with stem cells from other sources may be free of disease for 3 years or longer. The results of these treatment forms have improved considerably, but the continuing high treatment-related mortality warrants that these patients should be treated within investigational protocols.