Myelodysplastic syndromes (MDS)

Myelodysplastic syndrome (MDS) is a rare condition affecting the bone marrow – the spongy material found in bones. Bone marrow is where our blood cells are made. In MDS, the bone marrow doesn’t make enough healthy blood cells.

Symptoms can include:

  • feeling weak or tired
  • having lots of infections
  • bruising and bleeding easily.

To diagnose MDS, your doctor may suggest a blood test, or you may have a bone marrow test. This is when a sample of bone marrow cells is taken from your back or hip bone to be examined under a microscope.

MDS is divided into ‘risk groups’. These groups are low-risk, intermediate-risk or high-risk MDS. After your tests your doctor will tell you which group you are in.

Depending on your risk group and symptoms you may not have treatment straight away. Other people may have blood transfusions or an injection of growth factor to increase the number of blood cells. Other treatments include:

  • chemotherapy
  • a stem cell transplant.

Once treatment has finished you will have regular blood tests and check-ups.

Bone marrow

People with MDS have abnormal bone marrow. This means the bone marrow doesn’t make enough healthy blood cells.

Bone marrow is part of the immune system, which protects us from infection and disease. The bone marrow is the spongy material found inside bones. This is where stem cells are made. Stem cells are blood cells at their earliest stage of development. All blood cells grow from stem cells. Blood cells that aren't fully developed are called blasts. As blasts develop (mature), they become one of the three types of blood cells:

  • red blood cells, which carry oxygen around the body
  • white blood cells, which fight infections
  • platelets, which help blood to clot to prevent bleeding.

The bone marrow makes millions of blood cells every day. Developing blood cells stay inside the bone marrow. When they are fully grown, they are released into the bloodstream.

What is myelodysplastic syndrome (MDS)?

Myelodysplastic syndromes (MDS) are a group of conditions that affect the bone marrow. MDS is more common in people over 60, but it can happen at any age. It is sometimes called myelodysplasia.

There are different types of MDS. Some develop slowly, but others are more aggressive. Some types of MDS have a greater chance of developing into acute leukaemia. Your specialist can explain more about the type of MDS you have.

Causes of MDS

In most cases, the cause of MDS is unknown. If this is the case, it’s called primary MDS.

A small number of people develop MDS after treatment with chemotherapy or radiotherapy. This is called secondary or treatment-related MDS.

Signs and symptoms of MDS

The main symptoms of MDS are caused by low levels of healthy blood cells. Symptoms include:

  • feeling weak, tired and breathless due to a lack of red blood cells (anaemia)
  • repeated infections due to a low number of white blood cells (which help fight infection)
  • bruising or bleeding due to a low number of platelets (cells which help the blood to clot).

Some people are diagnosed with MDS when they have a routine blood test, before any symptoms have developed.

Diagnosing MDS

You will see a doctor called a haematologist, who specialises in blood disorders. MDS is diagnosed with blood tests and a bone marrow sample.

Full blood count (FBC)

This is a blood test that counts the numbers of red blood cells, white blood cells and platelets in your blood.

Bone marrow sample

A bone marrow sample will be taken for testing to find out more about the type of MDS you have.

A bone marrow sample being taken
A bone marrow sample being taken

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The sample is usually taken from the back of your hip bone (pelvis).

You will be given local anaesthetic to numb the area first. The doctor will then pass a needle through the skin into the bone and draw a small sample of liquid marrow into a syringe (bone marrow aspirate). After this, the doctor will take a small sample of marrow from the bone (a trephine). The samples will then be sent to the laboratory to be looked at under a microscope.

The sample can be taken on the ward or in the outpatients department. The whole procedure takes about 15–20 minutes. It may be uncomfortable as the marrow is drawn into the syringe, but this only lasts for a few seconds.

It’s normal to feel bruised and a bit sore for a few days after the test. Taking a mild painkiller, such as paracetamol, usually helps.

Cytogenetic tests

This test helps the doctor to diagnose what type of MDS you have. It is done on cells from the bone marrow aspirate. It looks at the chromosomes inside the cells. Chromosomes are groups of genes, which control the activities of the cell. In some types of MDS, there are changes in the chromosomes.

Types of MDS

MDS can be divided up (or classified) into different types. These are based on:

  • which blood cells are affected
  • how many immature (blast) cells there are
  • if there are chromosome changes in the blood cells.

There are 7 types of primary MDS:

Refractory cytopenia with unilineage dysplasia (RCUD)

Only one type of blood cell is affected. It is divided into 3 subtypes:

  • Refractory anaemia (RA) – a low number of red blood cells.
  • Refractory neutropenia (RN) – a low number of white blood cells.
  • Refractory thrombocytopenia (RT) – a low number of platelets.

Refractory anaemia with ring sideroblasts (RARS)

This type is like refractory anaemia (RA), but some of the immature (blast) cells in the bone marrow have a ring of iron in them. These cells are called ring sideroblasts.

Refractory cytopenia with multilineage dysplasia (RCMD)

This type affects two or more blood cells, which means two or more of your blood cell levels will be low. There are very few or no blast cells in the blood. There are some blast cells in the bone marrow.

Refractory anaemia with excess blasts (RAEB)

One or more of your blood cell levels are low. There are a greater number of blast cells in the blood and bone marrow. The cells look abnormal in the bone marrow.

RAEB is split into RAEB1 and RAEB2. In RAEB2, there are more blast cells in the blood and bone marrow than in RAEB1.

MDS associated with isolated del (5q)

In this type, the cells in the bone marrow have a chromosome change called isolated del (5q). The numbers of red cells in the blood are also low.

MDS unclassified (MDS-U)

This type is any type of MDS which does not fit into any of the above categories.

Your haematologist and nurse will be able to explain these types of MDS in more detail.

Risk groups for MDS

MDS is also divided into risk groups that give an idea about how the MDS may develop. The risk groups are based on your blood count, the number of blast cells and the results of cytogenetic tests.

A commonly used system for grouping MDS is called the International Prognostic Scoring System (IPSS). There are four groups:

  • low-risk
  • intermediate-risk 1
  • intermediate-risk 2
  • high-risk.

Your haematologist may sometimes use other risk groups to describe your MDS. They will explain more about your risk group.

Treating MDS

The best treatment for you will depend on the type of MDS you have, the risk group you are in, and your general health. Usually, the aim of treatment is to help to improve your blood counts and relieve symptoms.

If you have low-risk or intermediate-risk MDS and don’t have any symptoms, you may not need treatment straight away. Instead, you will have regular check-ups and your blood counts will be monitored. This is sometimes called ‘watch and wait’.

Most people with MDS have treatment at some point to help with the symptoms caused by low blood counts. This is called supportive treatment.

Chemotherapy may be helpful for some people, depending on the type of MDS they have. Sometimes, drugs that affect how the immune system works are used to treat MDS. These drugs are called immunosuppressants.

Some people may have treatment with a targeted (biological) therapy.

A small number of people who are in good general health may be able to have a donor stem cell transplant. The aim of this is to cure MDS.

Supportive treatment

Supportive treatment aims to help with the symptoms of MDS and improve your quality of life.


You may feel tired or short of breath. This is caused by low levels of red blood cells. Or you may have bruising and bleeding caused by low platelets levels. You can have blood or platelet transfusions to help improve these symptoms.

Red blood cells contain iron, so if you have a lot of blood transfusions, the level of iron in your body will increase. Too much iron can be harmful, and you may need treatment to reduce it. Your doctor or nurse will explain more about this treatment if you need it.

Growth factors

It may be possible to boost the number of healthy red and white blood cells in your blood with growth factors.

A growth factor called erythropoietin may be used to increase the amount of red blood cells in your blood and reduce the number of blood transfusions you need. A drug called G-CSF may be given to boost the number of white blood cells.

Both of these growth factors are given as injections under the skin (subcutaneously). Some people may get both drugs depending on their full blood counts.

Reducing your risk of infection

If your white blood cell level is low, you’re at an increased risk of infection. Your specialist nurse or doctor will give you advice about reducing this risk. You may be given drugs, such as antibiotics, to prevent or treat infections.


Chemotherapy is the use of anti-cancer (cytotoxic) drugs to destroy cancer cells. It can also be given to help control MDS. The type of chemotherapy you have will depend on your general health and how the disease is affecting you. The aim is to get the bone marrow working normally (remission).

Chemotherapy can be given as tablets, an injection into a vein (intravenously) or an injection under the skin (subcutaneously). You may be given a single drug or two or more drugs together (combination chemotherapy). Chemotherapy may be given as an outpatient or during a short stay in hospital. For some more intensive types of chemotherapy, you may need to stay in hospital for a few weeks.

Azacitidine (Vidaza®) is a chemotherapy drug for people with high-risk MDS who aren’t fit enough to have a stem cell transplant. It can help the bone marrow to work better. It is given as an injection under the skin. Side effects include discomfort at the injection site, sickness and tiredness. It also temporarily reduces the blood count.


Sometimes in MDS, white blood cells called T-lymphocytes affect normal blood cell production. Immunosuppressants work by making T-lymphocytes less active. Immunosuppressant drugs used to treat MDS include anti-thymocyte globulins (ATGs) and ciclosporin.

ATG is given as a drip through a vein. It is given in hospital because it can sometimes cause allergic reactions. Ciclosporin can be taken at home as capsules or a liquid.

Targeted (biological) therapy

Some people with isolated del 5q MDS may be given treatment with a targeted therapy called lenalidomide (Revlimid®). Lenalidomide works on the immune system to target the affected blood cells.

Stem cell transplant (from a donor)

A small number of people with MDS may be able to have a stem cell transplant from a donor, also called an allogenic transplant.

You have high doses of chemotherapy, and sometimes radiotherapy. The stem cells that have been destroyed by the treatment are then replaced. The replacement stem cells are from a donor. A donor can be a brother, sister or an unrelated person who is a match for you.

This treatment is only suitable for some people with MDS. Your specialist will discuss the possible benefits and disadvantages of this treatment with you.

Clinical trials

There are also newer treatments available that may be used to help to control MDS.

You may be invited to join a clinical trial that is looking at new ways of treating MDS. You can talk about this with your haematologist.

Your feelings

You may have different emotions including anger, resentment, guilt, anxiety and fear. These are all normal reactions, and are part of the process many people go through in trying to come to terms with their condition.

Everyone has their own way of coping with difficult situations. Some people find it helpful to talk to family or friends, while others prefer to get help from people outside their situation. Some people prefer to keep their feelings to themselves. There is no right or wrong way to cope, but help is there if you need it. Our cancer support specialists or these organisations can give you information about counselling in your area and other support:

  • Bloodwise provides information on MDS and other blood disorders.
  • Leukaemia CARE is a national group promoting the welfare of people with leukaemia and related blood disorders, including MDS.
  • MDS UK Patient Support Group is the only MDS dedicated patient support group in the UK. It offers networking opportunities, organises patient meetings, shares information and raises awareness across the UK.

Back to Other blood cancers

Myelofibrosis (MF)

Myelofibrosis (MF) is a type of bone marrow disease. Rarely, MF leads to leukemia.