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Bone marrow disorders that would qualify as what we now call myelodysplastic syndromes (MDS) have been recognized for at least a century . However, it was not until the 1970s and early 1980s that Bennett et al. presented a classification system . This French-American-British (FAB) classification proved to be very helpful for clinical prognostication and treatment decisions. The more recent development of the International Prognostic Scoring System (IPSS) by Greenberg, et al. , and the subsequent proposal by the World Health Organization [4,5] reflect our improving understanding of various parameters that impact the disease course. The addition of red blood cell transfusion dependence to the WHO scoring system in the WPSS may have further improved our ability to predict patient risk and prognosis .
The recognition as a clonal disorder of hematopoietic stem/precursor cells identified MDS as a disease that should be treatable and potentially curable by hematopoietic cell transplantation (HCT) . This proved indeed to be the case, and by now some patients have been followed for more than 25 years, apparently cured of their disease . However, this modality of treatment has been applied only to a small proportion of patients, either because of concerns about the toxicity associated with HCT in patients who might have a life expectancy of several years with conservative management; because of age, a most relevant factor since the median age at diagnosis of MDS is in the eighth decade of life; or because of the lack of a suitable donor [9,10]. Various developments in the field of HCT, however, have expanded the indications for transplantation and have reduced the morbidity and toxicity associated with the procedure [11-13].
Concurrently, studies aimed at characterizing at the cellular and molecular levels the pathophysiology of MDS have resulted in new insights and the development of non-transplant therapies. The FDA approval of three drugs (5 azacitidine; 5 aza-2′deoxyazacitidine; lenalidomide) for the treatment of MDS over the past few years has led to extensive studies on the indications, efficacy and limitations of these drugs [14-18]. Other modalities of treatment such as immunosuppression or cytokine blockade have shown promise in subgroups of patients [19-22]. Those studies, in turn, have stimulated interest in further defining various aspects of the pathogenesis and pathophysiology of MDS.
At the same time, a proportion of patients who are being treated successfully with chemotherapy or radiation for various diagnoses has been found to develop MDS, apparently secondary to the effects of cytotoxic therapy [23-25]. These treatment-related cases of MDS tend to behave more aggressively and generally are more difficult to treat than de novo MDS.
In this symposium, three experts are providing an update on transplant and non-transplant therapy for MDS and our current understanding of secondary MDS.
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