Myelodysplasia: when to treat and how.

Myelodysplastic syndrome (MDS) is a disorder of hematopoietic stem cells characterized by ineffective hematopoiesis. The result is pancytopenia leading to transfusion-dependent anemia, an increased risk of infection or bleeding, and a potential to progress to acute myeloid leukemia (AML). MDS is most prevalent among older individuals, many of whom also suffer from other medical conditions. MDS is classified according to World Health Organization criteria and the International Prognostic Scoring System. Supportive care remains the mainstay of therapy. Those with low-risk MDS can often be monitored for an extended period of time without specific therapy, whereas those with intermediate- or high-risk MDS benefit from treatment. Currently, only azacitidine is approved for the treatment of MDS. Several new agents are being tested, including inhibitors of angiogenesis (thalidomide, lenalidomide), farnesyl transferase inhibitors (lonafarnib, tipifarnib), and DNA methyltransferase inhibitors (azacitidine, decitabine). Lenalidomide appears particularly effective in patients with low-risk MDS with the deletion of chromosome 5q31. Allogeneic stem cell transplantation is an alternative for high-risk MDS. With advances in transplantation techniques, this treatment can be offered to an increasing number of patients. However, it is necessary to assess each patient's disease individually and to evaluate prognostic factors, other treatment options, and the appropriateness and timing of transplantation.