Skip to main content

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

Although in most cases it is not clear what causes the genetic changes that lead to MDS, there are some known risk factors. A “risk factor” is anything that increases a person’s chance of developing a disease.

The factors that are associated with an increased risk of developing MDS include:

  • Age: Risk increases with age
  • Sex: Males are more likely than females to develop MDS.
  • Genetic disorders: Certain genetic conditions present at birth seem to increase the risk 
  • Familial risk/germline predisposition 
  • Previous cancer treatment (This is referred to as "secondary" or "treatment-related MDS." 
  • Smoking
  • Workplace exposure to benzene among agricultural and industrial workers 


Source: Myelodysplastic Syndromes. Reviewed by Guillermo Garcia-Manero, MD