Intensive Chemotherapy and Stem Cell Transplantation in Myelodysplastic Syndromes
The myelodysplastic syndromes (MDS) include a heterogeneous group of clonal disorders of the hematopoietic stem cell, with widely varying natural histories and risks for disease-related complications, including progression to acute myeloid leukemia (AML) or death from the effects of peripheral blood cytopenias (1). The incidence of MDS increases markedly with age (see chap. 2), and since the median age of patients is above 70 years, many patients with MDS have important comorbid conditions at presentation that complicate therapeutic decisions, especially those involving more intense and riskier therapies (2,3). When MDS occurs in younger patients, the disease is often preceded by treatment with radiotherapy or certain chemotherapeutic agents, such as alkylating substances and topoisomerase II inhibitors (see chap. 8) (4-6). Such an exposure history marks patients’ disease as high risk, and furthermore, other residual nonhematological effects from those prior treatments may also limit the ability to successfully deliver intensive therapy for MDS.