Contact UsAbout MDS
Myelodysplastic syndromes (MDS)* are a group of diseases of the blood and marrow, with varying degrees of severity, treatment needs and life expectancy.
MDS starts with a change to a normal stem cell in the marrow. With MDS, the marrow becomes filled with an increased number of developing blood cells. The blood is usually deficient in cells because the developing cells in the marrow die before they can be released into the blood. Normally, immature cells known as "blasts" make up less than 5 percent of all cells in the marrow. In MDS patients, blasts often constitute more than 5 percent of the cells. A patient with more than 20 percent blasts in the marrow is diagnosed with acute myelogenous leukemia (AML).
MDS has been known as "smoldering leukemia," or "preleukemia." These terms may be misleading because they imply that MDS is only serious and problematic after it has evolved into AML, which is not the case.
The most common specific MDS subtypes are refractory anemia (RA), 15 percent, and refractory anemia with excess blasts (RAEB), 14 percent.
People diagnosed with MDS, not otherwise specified (MDS NOS) comprise 52 percent of all MDS cases. People diagnosed with therapy-related MDS comprise less than 2 percent of all reported cases.
* MDS facts and statistics from Leukemia, Lymphoma, Myeloma, Facts 2009-2010, June 2009.
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New Cases and Incidence
The overall incidence rate of MDS is estimated at close to four cases per 100,000 persons. MDS most commonly strikes males ages 70 and above.
From 2002 to 2006 there were approximately 56,841 cases of MDS throughout the United States, averaging an estimated 11,368 cases per year.
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Incidence by Gender
For the five-year period from 2002 to 2006, there were approximately 31,202 cases in males, averaging 6,240 per year, and 25,639 cases in females, averaging 5,128 per year. This results in an incidence rate of 5.4 cases per 100,000 for males, and a much lower 3.1 cases per 100,000 for females.
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Incidence by Race and Ethnicity
White males have the highest incidence rates (5.6 cases per 100,000), while American Indian and Alaskan Native females and Asian and Pacific Islander females have the lowest incidence rates (2.3 cases per 100,000 for each population group).
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Signs and Symptoms
Most often persons diagnosed with MDS first seek medical attention because they are experiencing fatigue and shortness of breath (from anemia). Some persons have no symptoms and a diagnosis of MDS is made as a result of a routine physical examination and testing.
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Possible Causes
MDS may be a primary diagnosis or the diagnosis may be secondary to treatment with chemotherapy and radiotherapy for certain other cancers. Only a small proportion of people exposed to chemotherapy or radiation therapy develop MDS.
Another possible cause is repeated exposure to the chemical benzene. Benzene is found in certain industrial settings, but regulation has reduced workplace exposure. Tobacco smoke is now the most common known cause of benzene exposure.
The vast majority of persons with MDS have primary MDS, which usually has no clear-cut triggering event.
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Treatment
The goals of therapy for MDS vary based on patient risk factors. The goal for patients with lower-risk MDS is to manage the disease by reducing transfusion needs and infection risk, and also increasing the number years of good quality of life.
Today, the only potentially curative therapy is high-dose chemotherapy with allogeneic stem cell transplantation. This may be a practical option for certain younger patients with higher-risk MDS whose life expectancy without successful treatment warrants the risk associated with transplantation.
Other general approaches to treatment (used alone or in combination) include: a watch-and-wait strategy; transfusion; administration of blood cell growth factors; drug therapy with newer agents such as azacitidine, decitabine, and lenalidomide; or chemotherapy of the type used to treat AML.
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Survival
On Jan. 1, 2005, there were 25,473 people in the United States living with, or in remission from, MDS. Because the National Cancer Institute, SEER program, only recently began maintaining statistics for MDS, this is a four-year prevalence figure, as opposed to the 31-year prevalence figures reported for other types of cancer.
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Deaths
Data for the number and rates of deaths from MDS are not yet available.
For more information on treatment and supportive care for MDS, please view, print or order the following free LLS booklets:
Myelodysplastic Syndromes
Blood and Marrow Stem Cell Transplantation
Blood Transfusion
Understanding Clinical Trials for Blood Cancers
Understanding Drug Therapy and Managing Side Effects
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