Myelodysplastic syndromes (MDS) refer to a group of hematopoietic disorders characterized by ineffective hematopoiesis and increased risk of transformation to acute myelogenous leukemia (AML). Most patients with MDS succumb to causes related to the disease. The median age of patients with MDS is 70 to 75 years. It is likely that environmental factors play an important role in the pathogenesis of this disease. Myelodysplastic syndromes are classified according to the World Health Organization (WHO) criteria, and a number of prognostic scores can be used to calculate survival and risk of transformation. Cytogenetic, genomic, and epigenetic alterations are common in MDS and help in the prediction of prognosis and potentially in the selection of therapy. Over the last decade, we have witnessed significant improvements in supportive care and therapeutic modalities for patients with MDS. These include growth factors, immune modulatory agents (lenalidomide), and hypomethylating agents (5-azacitidine and decitabine). We also better understand patient subgroups, such as those with hypomethylating failure disease. In this chapter, we summarize our knowledge of MDS and the treatment approach we use at MD Anderson Cancer Center.
THE MD ANDERSON APPROACH TO THE PATIENT WITH MDS
Every year, approximately 350 to 400 patients are referred to our center with a diagnosis of MDS. Nearly 20% of patients referred with a diagnosis of MDS receive a different diagnosis in our center. In most instances, the final diagnosis is that of AML or a form of higher-risk MDS. Other benign and malignant conditions can also be observed. In a study of 915 patients referred between 2005 and 2009 and using very strict criteria, 12% were reclassified when initially evaluated here (1). This justifies our practice to repeat a confirmatory bone marrow aspiration and biopsy at the time of initial MDS evaluation at MD Anderson.
Once the diagnosis is confirmed, the next important step is to calculate the “risk” of the patient. Most clinicians and investigators still use the International Prognostic Scoring System (IPSS) (2) score to perform such analysis, but newer potentially more precise models, such as the Revised International Prognostic Scoring System (IPSS-R), have been developed (3,4,5). In general, patients with low or intermediate-1 risk by the IPSS or those with less than 10% blasts in the bone marrow are considered as having “lower” risk disease, whereas those with excess blasts or intermediate-2 or high-risk disease are considered as having “higher” risk disease.
Patients with lower risk disease can be candidates for a wide range of interventions, depending on their specific characteristics and transfusion needs. Patients with minimal cytopenias, who are transfusion independent, who have a low percentage of blasts in the bone marrow, and have diploid cytogenetics are more frequently observed, as their 4-year survival is close to 80% (4). At the end of the spectrum, older patients with significant cytopenias and transfusion needs ...