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Myelodysplastic Syndrome

The term "myelodysplastic syndrome" (MDS) encompasses a group of diseases in which the blood-forming cells of bone marrow are damaged, leaving a person without enough normal blood cells. According to the American Cancer Society, about one-third of MDS patients progress to acute myeloid leukemia, a rapidly-growing cancer of the bone marrow. MDS itself is thought of as a form of cancer in that it is a clonal disease--the large population of abnormal cells all derive from a single abnormal cell, a typical characteristic of cancers.

  1. Classifying MDS

    • The World Health Organization (WHO) divides MDS into eight types, mostly determined by the abnormal appearance of blood cells in the bone marrow and blood. One type is determined by an abnormality in the chromosomes of the marrow. Refractory anemia (low red blood cells) and refractory cytopenia (low counts of at least two types of blood cells) are classified further based on characteristics of the blood cells. Refractory means the condition does not yield readily to treatment.

    Risk Factors

    • The single biggest risk factor for MDS is prior chemotherapy treatment. If the chemotherapy drugs that lead to MDS are combined with radiation treatment, the risk is even greater. This type of MDS is more common after treatment for childhood acute lymphocytic leukemia, non-Hodgkin lymphoma or Hodgkin disease and is also seen in recipients of stem cell transplants.

      Some genetic syndromes such as Fanconi anemia or familial platelet disorder can lead to MDS. Family history, smoking and environmental exposures (such as exposure to benzene or heavy metals such as lead and mercury) are also risk factors. MDS is more common in men and less common in those under age 40. MDS occurs most often in those over age 60.

    Signs and Symptoms

    • Shortages of blood cells are a sign of MDS. Anemia causes pallor, fatigue and shortness of breath. Leukopenia (low white blood cells, of which there are five types) can lead to severe or frequent infections. Thrombocytopenia (low platelets) can cause easy bruising and bleeding. Someone with MDS may also have fever, loss of appetite and weight loss. These symptoms can also be attributed to other conditions, so evaluation by a doctor is essential to determine the cause of low blood counts.

    Treatment

    • MDS has no cure or definitive treatment. Instead, symptoms are managed with supportive care. Depending on the type of MDS, the patient may receive blood transfusions or medications to increase the body's number of healthy blood cells. In rare cases, a bone marrow stem cell transplant may be used to treat MDS. However, those most likely to have myelodysplastic syndrome--older adults--are less able to tolerate the high risks of a stem cell transplant. According to staff at the Mayo Clinic, even among young people, complications from stem cell transplants are high.

    Prognosis

    • The outcome of myelodysplastic syndrome depends on its classification and any other associated disorders the patient may have. According to the American Cancer Society, a "very low risk" patient has a median survival rate of 12 years, while a "very high risk" patient has a median survival rate of nine months. Median survival rate is the amount of time it takes for half the patients in the group to die. Half will not survive as long, and half will survive longer.

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