Myelodysplastic syndromes (MDS) are potentially life-threatening diseases involving abnormal myeloid stem cells. Doctors use the International Prognostic Scoring System (IPSS) or the World Health Organization Prognostic Scoring System (WPSS) to determine the prognosis of MDS. MDS can cause cytopenias or abnormalities in white blood cells, red blood cells, or platelets. Some types of MDS can progress to acute myeloid leukemia (AML). The accuracy of MDS prognosis is important in determining the best treatment for patients, as well as in classifying medical study participants.
Myelodysplastic syndromes (MDS) are a group of diseases involving abnormal myeloid stem cells. Myeloid stem cells are produced by the bone marrow and develop into white blood cells (WBCs), red blood cells (RBCs), or platelets, and myeloid stem cell diseases are potentially life-threatening. Doctors primarily use the International Prognostic Scoring System (IPSS) or the World Health Organization Prognostic Scoring System (WPSS) to determine the prognosis of myelodysplastic syndrome. Both of these systems use factors including bone marrow myoblast percentage, cytogenetic abnormalities, number of cytopenias, gender, and age to predict possible patient outcomes. Blood serum lactate dehydrogenase activity and the patient’s dependence on blood transfusions may also be helpful in the prognosis of myelodysplastic syndrome.
Myelodysplastic syndromes can develop due to genetic factors, in people who have had chemotherapy or radiation treatments or been exposed to toxins such as benzene, or for unknown reasons. MDS can cause cytopenias, or insufficient cell numbers, of white blood cells, red blood cells, or platelets, or abnormalities in these cells. Patients can also develop iron overload. Some types of MDS can progress to acute myeloid leukemia (AML), so MDS is sometimes called “preleukemia” or “smoking leukemia.” The accuracy of myelodysplastic syndrome prognosis is important in determining the best treatment for patients, as well as in classifying medical study participants.
Scientists at an MDS risk analysis workshop developed the IPSS in 1997 and it has since become the most commonly used system for prognosis of myelodysplastic syndrome. The IPSS categorizes MDS cases according to the percentage of bone marrow myoblasts, cytogenetic abnormalities, and number of cytopenias. Doctors use these categories to determine the prognosis of myelodysplastic syndrome, which includes patients’ expected overall survival and risk of developing leukemia.
Using the IPSS criteria, myelodysplastic syndrome patients with too few red blood cells but normal levels of platelets and white blood cells have refractory anemia (RA), and RA patients whose red blood cells also contain too much iron have refractory anemia with ring sideroblasts (RARS). Refractory anemia with excess blasts (RAEB) refers to MDS with too few red blood cells and in which 5 percent to 19 percent of the blood cells in the bone marrow are blasts or immature blood cells, along with possible blood cell abnormalities whites and platelets. Myelodysplastic syndrome patients with too few red blood cells, white blood cells, and platelets, where blasts comprise 20 to 30% of blood cells in the bone marrow and 5% or more in the blood, have refractory anemia with excess transforming blasts (RAEB-T). Refractory cytopenia with multilineage dysplasia (RCMD) means that a patient has too few or more of one type of blood cell. Some cases of myodysplastic syndrome are associated with an isolated del(5q) chromosome abnormality, and cases of unclassified MDS involve cytopenia of a type of blood cell and a normal number of blasts.
The MDS Risk Analysis Workshop found that RARS patients are likely to survive longest, followed by RA patients. RAEB patients had a significantly shorter life span than those with RARS or RA, and RAEB-T patients had the shortest expected survival; none of the RAEB-T patients in the analysis lived more than 5.5 years after MDS diagnosis. The prognosis of myelodysplastic syndrome was better for female patients than for males, and patients older than 60 years had a reduced survival. RARS and RA patients had the least chance of developing AML, while RAEB patients had a significantly higher risk. All RAEB-T patients studied in the workshop developed AML within four years of being diagnosed with MDS.
The WPSS divides RAEB into types one and two (RAEB-1 and RAEB-2) for the purpose of myelodysplastic syndrome prognosis. 5% to 9% of the blood cells in the bone marrow of RAEB-1 patients are blasts and less than 5% in the blood are blasts. In patients with RAEB-2, 10% to 19% of blood cells in bone marrow and 5% to 19% of blood cells in blood are blasts. Patients with RAEB-1 have about a 25% risk of developing AML, while patients with RAEB-2 have a 33% risk.
Following the development of IPSS and WPSS, scientists have identified more factors that influence leukemia risk and overall survival for patients with MDS. Patients with myelodysplastic syndrome without excessive blasts and who are dependent on blood transfusions have a significantly higher risk of leukemia and shorter overall survival than patients who do not require transfusions. Transfusion dependence is also a significant independent risk factor for patients with RARS and del(5q) MDS. MDS patients who have higher white blood cell levels at the time of MDS diagnosis tend to survive longer, and patients with elevated serum lactate dehydrogenase activity have reduced overall survival. In mid-2011, scientists continued efforts to refine the prognosis of myelodysplastic syndrome.
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