Myelodysplastic Syndromes (MDS)

Myelodysplastic syndromes are diseases that effect normal blood cell production and behavior. Blood carries oxygen, chemicals and hormones to the cells in the body and helps remove toxins and waste. Bone marrow (the spongy middle part of the large bones) produces the three main categories of blood cells:

  • Red blood cells carry oxygen to the tissues (muscles, bones, nerves and organs). Low or malfunctioning red blood cell production may cause anemia. Symptoms are paleness, tiredness, fast beating or pounding heart, dizziness, shortness of breath or headaches.
  • White blood cells fight infection. Symptoms of infection caused by low white blood counts may include temperature rising to 38.0º C or 100.4º F, coughing, stiff neck, pain or burning with urination, sore throat, mouth or lip sores and sores that do not heal.
  • Platelets help to prevent bleeding. Signs of inadequate platelets include bleeding or bruising too easily. Patients may experience bleeding of the gums when brushing their teeth, blood in the urine or stool, severe headache or visual changes or a stiff neck.

MDS may remain stable for several years, or it may get worse quickly and progress to acute myeloid leukemia. The five categories of MDS are:

  • Refractory anemia
  • Refractory anemia with ringed sideroblasts
  • Refractory anemia with excess blasts
  • Refractory anemia in transformation to acute leukemia
  • Chronic myelomonocytic leukemia

The disease categories on the lower end of this list are more serious and have a worse prognosis than those at the top.

The two forms of MDS that primarily affect the red blood cells are refractory anemia and refractory anemia with ringed sideroblasts. These are the most common forms of MDS.

  • Refractory anemia with excess blasts. Immature white blood cells are found in the bone marrow in abnormally large numbers (5 to 20% bone marrow blasts). Normally, the bone marrow has less than 1% blasts.
  • Refractory anemia with excess blasts in transformation. Blasts become markedly increased (more than 20%). This may indicate that MDS will change to an acute form of leukemia.

Risk Factors

  • May have no apparent cause
  • Exposure to certain chemicals, such as pesticides
  • Exposure to chemotherapy or non-chemotherapy drugs and radiation
  • Possibly age (MDS is most commonly diagnosed in people 60 and older.)

Signs and Symptoms

MDS is difficult to diagnose because of the absence of symptoms in the early stage of the disease. Often it is accidentally discovered during a routine physical exam or blood test. When symptoms appear, they are usually subtle. The most common are:

  • Signs of anemia, such as weakness, tiredness, headaches, heart palpitations and dizziness
  • Low platelet counts cause easy and profuse bleeding, as well as unexplained bruising
  • Heavy menstrual periods
  • Susceptibility to infection due to low number of white blood cells

Diagnosis

Routine screening tests do not exist for MDS. If the disease is suspected, however, the doctor may order these tests:

  • Complete blood count. A small amount of blood is drawn and the lab measures the red blood cells, white blood cells and platelets in the sample.
  • Bone marrow biopsy. This procedure is usually done under local anesthesia on an outpatient basis. A needle is inserted into the spongy middle part of the bone (marrow) in either the pelvic area or sternum (breastbone), and a small sample is taken for examination in the lab. About one teaspoon of blood is also withdrawn for a bone marrow aspirate. This procedure may cause some minor discomfort, but it is usually well tolerated by patients.
  • Cytogenetic test. Examines cell chromosomes (genetic material) from a bone marrow sample. Changes in chromosomes may be the result of certain types of MDS and are only rarely inherited.

Treatment

MDS is a progressive disease. As bone marrow becomes more affected, blood cells become more abnormal. Since none of the treatment procedures are effective in preventing MDS from worsening, it is standard to treat the symptoms of the disease. Doctors will discuss with the patient the various treatment options available, which include:

  • Antibiotics are used to treat infection.
  • Red blood cell or platelet transfusions can stop symptoms of low red blood cell count (anemia) or bleeding (low platelet count).
  • Chemotherapy drugs are injected into the vein to kill cancer cells.
  • Biologic therapy. Biologic response modifiers use the body's natural defense mechanism to stimulate production of white or red blood cells or platelets.
  • Differentiating agents (drugs) use Vitamin A or Vitamin D compounds to stimulate immature cells to become healthy mature ones.
  • Bone marrow transplant. Patients younger than 55 may be candidates for this procedure that destroys unhealthy marrow with high doses of chemotherapy (with or without radiation) and then replaces the diseased bone marrow with healthy marrow.
  • Leukemia treatment. MDS may change into acute myelogenous leukemia (AML). AML causes large numbers of immature white blood cells to be produced by the bone marrow. When this occurs, the patient is treated for AML rather than MDS. Patients with refractory anemia with excess blasts and chronic myelomonocytic leukemia have a higher risk of progression.

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