This information is about a group of conditions known as the myelodysplastic syndromes (MDS). They are a group of disorders affecting the bone marrow. They are not types of cancer, but can develop into leukaemia. However, the symptoms are often very similar to those caused by cancer, and the treatments used are also similar.

—      The bone marrow

—      The myelodysplastic syndromes

—      Causes of myelodysplasia

—      Signs and symptoms

—      How it is diagnosed

—      Treatment

—      New treatments

—      Support

—      References

The myelodysplastic syndromes

Myelodysplasia (pronounced my-low-dis-play-sia) is an abnormality of the bone marrow, which gradually affects the production of healthy blood cells.

Classification of MDS

Classification systems are used to break myelodysplasia down into various sub‑types. A commonly used classification system in the UK was produced by the World Health Organisation (WHO). The system looks at how many abnormal, immature cells (blasts) there are, and the characteristics (cytogenetics) of the abnormality. The subtypes are:

—      refractory anaemia with or without ring sideroblasts (RA or RARS)

—      refractory cytopenia with multilineage dysplasia (RCMD)

—      5q-syndrome

—      refractory anaemia with excess blasts (RAEB)

—      unclassified (does not fit into the above groups).

The myelodysplastic syndromes are further separated into low- intermediate- or high- risk groups, depending upon the number of abnormal immature blood cells (blasts) that are seen, the characteristics of the abnormality, and how the disease is affecting the normal number of healthy blood cells. The risk group will help your doctors decide on the best treatment for you, and will give them some idea of how well your disease will respond to the treatment.

In low-risk disease the bone marrow is only slightly affected and the disease develops quite slowly.

In intermediate-risk myelodysplasia the disease is slightly more advanced. This risk group is often split into two sub-groups: low-intermediate- and high‑intermediate- risk.

In high-risk disease the bone marrow is more widely affected and the disease can progress more quickly.