What are myelodysplastic syndromes?

Myelodysplastic syndromes (MDS) are types of blood cancers where the bone marrow does not have enough healthy blood cells. Instead, the bone marrow makes underdeveloped blood cells that have an abnormal size, shape and appearance, called dysplastic cells. The imbalance of dysplastic and healthy cells in the bone marrow can range from mild to severe. Myelodysplastic syndromes most often happens in older adults.
Woman with MDS

In Canada, it is estimated that up to 5,900 new cases of MDS are diagnosed each year.

You are not alone.

Know that the blood cancer community is here to support you every step of the way.

What happens next?

Experiences of others with myelodysplastic syndromes

Gail Whiteford

Gail Whiteford

And now 5 years have passed. I am back working and volunteering and am able to see my daughter, Allison.

Calgary AB

More Detailsabout Gail Whiteford

Resources on myelodysplastic syndromes

There are two main types of MDS.

There are two main types of MDS: primary (de novo) and secondary MDS. The treatment for MDS varies according to the type and stage of the disease with the goal of slowing or stopping the MDS from becoming acute myeloid leukemia (AML). After treatment, many people get relief from the symptoms of MDS. You may find that knowing more about the disease and its treatment can help you cope.


Doctors classify myelodysplastic syndromes into subtypes by using various tests. The subtype plays a large part in deciding the type of treatment.

  • Chronic myelomonocytic leukemia (CMML) - More information available

  • Refractory anemia (RA)/myelodysplasia

  • Refractory anemia with ringed sideroblasts (RARS)/acquired sideroblastic anemia or myelodysplasia

  • Refractory anemia with excess blasts (RAEB)/smoldering leukemia/oligoblastic myelogenous leukemia

  • Refractory anemia with excess blasts in transformation (RAEB-T)