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Myelodysplastic Syndromes

Myelodysplastic syndromes (MDS)

  • Is a diagnosis of cancer
  • Is a group of diseases that affect the blood and marrow, with varying degrees of severity, treatment needs and life expectancy
  • May be primary (de novo) or treatment-related. Primary MDS has no obvious cause. Treatment-related MDS has an obvious cause.

Click here to access MDS statistics.

What You Should Know

  • Hematologists and oncologists are specialists who treat people who have MDS or other types of blood cancer.
  • Treatment outcomes vary widely among patients; results depend on many individual factors.

What You Should Do

  • Seek treatment in a cancer center where doctors are experienced treating patients with MDS.
  • Talk with your doctor about your diagnostic tests and what the results mean.
  • Ask your doctor whether a clinical trial is a good treatment option for you.

To download lists of suggested questions to ask your healthcare providers, click here.

How Does MDS Develop?

The DNA (genetic material) of a developing stem cell in the bone marrow is damaged. This is called an “acquired mutation.”

  • Stem cells form blood cells (white cells, red cells and platelets).

This prevents the normal functioning of the bone marrow. When the bone marrow does not work properly, it cannot make enough healthy blood cells.

  • The bone marrow produces underdeveloped (immature) cells that are abnormal in size, shape or appearance, which are called “dysplastic” (abnormally formed) cells.
  • There can be an accumulation of blast cells (immature bone marrow cells), which cannot yet perform the specific function of a mature cell.
  • The bone marrow fails to produce enough healthy red blood cells, white blood cells or platelets.

As a result, the number of healthy blood cells (red cells, white cells and platelets) is usually lower than normal.

  • Anemia is a condition when there is a low number of red cells in the blood which can cause fatigue and shortness of breath.
  • Neutropenia is a condition when there is a low number of white cells so that the immune system can't effectively guard against infection due to a lack of neutrophils (a type of white cell).
  • Thrombocytopenia is a condition when there is a low number of platelets which can cause bleeding and easy bruising with no apparent cause.
  • Pancytopenia is a condition when all three types of blood cell counts are low.

However, marrow cell disturbances in MDS patients range from mild to very severe.

  • In some patients, the MDS cells can still function and enter the blood. Red cells continue to carry oxygen, white cells (neutrophils and monocytes) ingest and kill bacteria and platelets plug up injury to blood vessels.
  • In more severe cases of MDS, blood cell formation is more disordered and abnormal blast cells (blasts) accumulate in marrow and blood. These cells don't mature into cells that function properly. They aren't as capable as normal cells are of maturing into red cells, neutrophils and platelets.
  • Normally, blasts make up less than 5 percent of all cells in the marrow. With MDS, blasts often make up more than 5 percent of cells in marrow. The number of blasts is key to determining how severe the MDS is.

Risk Factors

Doctors can’t identify a specific cause in the majority of MDS cases. MDS can either be primary, also known as “de novo,” when the cause is not known, or secondary, known as “treatment related.” Most people who have MDS are diagnosed with primary or de novo MDS

  • Primary or de novo MDS - The disease does not have a known cause. In most cases, random mutations (DNA changes) accumulate in the stem cells with aging, and if these mutations occur in specific genes and in particular locations, MDS results.
  • Secondary (treatment-related) MDS - Some people who have received treatment for another cancer have a small risk of developing treatment-related MDS. This occurs only in a small number of patients exposed to chemotherapy and/or radiation therapy and is less common than cases of primary MDS. In general, the chance of developing MDS as a result of treatment for another cancer is very low. Some patients with rare inherited bone marrow disorders such as Fanconi anemia or dyskeratosis congenita can also develop secondary MDS, as can patients previously diagnosed with another bone marrow failure disorder called aplastic anemia.

There is no way to prevent MDSs and you cannot catch them. 

Source: Myelodysplastic Syndromes. Reviewed by Amy Elizabeth DeZern, MD, MHS.