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Myelodysplastic syndromes (MDS)

This page tells you about myelodysplastic syndromes (MDS) and their treatment. There is information about


What myelodysplastic syndromes are

Myelodysplastic syndromes are blood disorders. This group of conditions causes a drop in numbers of normal blood cells. You may also hear them called myelodysplasia or MDS for short. They get their name from myelo, meaning bone marrow, and dysplasia, meaning abnormal growth.

The bone marrow is the soft inner part of our bones that makes blood cells. All blood cells start from the same type of cell called a stem cell. The stem cell makes immature blood cells. The immature cells go through various stages of development before they are released into the blood as fully developed blood cells

  • Red blood cells to carry oxygen around our bodies
  • White blood cells to fight infection
  • Platelets to help the blood clot

The diagram shows how the various different types of cells develop from a single blood stem cell.


With myelodysplastic syndromes the bone marrow makes too few normal blood cells. The blood cells it does make are not fully developed and not able to work normally. These abnormal blood cells then either stay in the bone marrow or are destroyed before they get into the bloodstream. As the condition develops, the bone marrow becomes full. The immature blood cells then spill out into the bloodstream. The low numbers of normal blood cells in the bloodstream eventually cause symptoms. The symptoms may be difficult to control.

Myelodysplastic syndromes are most common in people between the ages of 65 to 70. Only 1 in 5 people (20%) with MDS are younger than 50.


Causes of MDS

We don't know what causes most cases of MDS. You may hear this called primary MDS.

But we do know of some risk factors that increase the risk of developing MDS. One of these is exposure to the chemical benzene. People are most likely to come into contact with benzene through their work. It is used in the rubber industry and is one of the chemicals in petrol. There is also benzene in traffic pollution, although levels are too low to make this a likely risk factor. It is also in cigarette smoke.

More rarely MDS is caused by radiotherapy or chemotherapy treatment for cancer. This is called secondary or treatment related MDS.


Signs and symptoms of MDS

Some people with a myelodysplastic syndrome don’t have any symptoms at all. Their MDS is picked up on a routine blood test for something else. For most people, symptoms tend to be mild at first and get worse slowly. The symptoms are caused by a drop in the number of blood cells and may include

  • Tiredness, and sometimes breathlessness because of a low red blood cell count (anaemia)
  • Frequent infections because of a low white blood cell count
  • Bleeding (such as nosebleeds) or bruising easily because of a low platelet count

Types of myelodysplasia

There are different types of myelodysplastic syndrome. Some types affect one type of blood cell. Other types affect all types of blood cells. Some types develop slowly, so that the bone marrow gradually makes fewer normal mature cells. Other types develop more quickly.

Doctors divide the different types of MDS into groups or subtypes. The system they use is called a classification system. The most used classification system for MDS in the UK is the World Health Organisation (WHO) system. This generally looks at how many immature cells (blasts) there are in the blood and bone marrow, and how normal the cells are. 

Using this system, there are 7 types of MDS. This is quite complicated, and your doctor or nurse can explain it in more detail.

Refractory cytopenia with unilineage dysplasia (RCUD)

This affects a single type of blood cell. It can be divided into 3 subtypes

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

Refractory anaemia with ring sideroblasts (RARS)

This is similar to refractory anaemia (RA). But there are a greater number of early red blood cells in the bone marrow that have a ring of iron around the nucleus. These cells are called ring sideroblasts.

Refractory cytopenia with multilineage dysplasia (RCMD)

The MDS affects more than one type of blood cell. So 2 or more of your blood cell levels will be low. There are very few or no immature cells (blasts) in the blood. There are a small number of blasts in the bone marrow.

Refractory anaemia with excess blasts (RAEB-1 and RAEB-2)

One or more of your blood cell levels are low, and many of these cells look abnormal in the bone marrow. There are a greater number of immature cells (blasts) in the blood and bone marrow.

Myelodysplastic syndrome associated with isolated del (5q)

In the bone marrow, the cells have a particular change in part of a chromosome. There are low numbers of red cells in the blood (anaemia). The platelet count is usually normal or high.

Myelodysplastic syndrome unclassified (MDS-U)

This covers any type of MDS that does not fit into one of the above groups.


Risk groups for MDS

As well as the different types of MDS, doctors group them according to how the disease is most likely to develop.

In some people, MDS will develop into an acute myeloid leukaemia (AML). Doctors call this transformation. Some types of MDS have a higher risk of transforming into AML than others. The risk varies from around 5 in every 100 cases (5%) to 65 out of every 100 cases (65%) depending on the type of MDS. Transformation may happen after a few months for some types of MDS but after several years for others. You can ask your doctor about the risk of transformation with your type of MDS

The system for grouping MDS according to likely outcome is called the International Prognostic Scoring System (IPSS). There are 4 risk groups

  • Low risk
  • Intermediate risk 1
  • Intermediate risk 2
  • High risk

The risk group depends on the number of immature cells (blasts) in your bone marrow and blood, on your blood cell levels, and on whether there are chromosome changes in the affected blood cells.

Knowing what type of MDS you have and your risk score helps your doctor to decide on the best treatment for you.


Diagnosis of MDS

To diagnose MDS, you have blood tests and bone marrow tests.

The blood tests show how many normal blood cells you have and how many abnormal or immature cells. As well as looking at the bone marrow cells, your doctor tests for abnormalities in your chromosomes. Chromosomes contain the genetic material inside the cells. These tests are called cytogenetics (pronounced sigh-toe gen-et-ics).


Treatment for myelodysplasia

The type of treatment depends on

  • Your type of MDS
  • Your risk group
  • Whether you have any other health conditions

The aim of treatment is to get the number and type of blood cells in the bloodstream back to normal.

If your MDS is classed as low risk, you are likely to have very few or no symptoms. You may not need treatment at first. Instead you will have regular check ups including blood tests. At some point, most people need to have treatment to control the symptoms of a low blood cell count. This is called supportive treatment.

If you have intermediate 2 or high risk MDS you will need prompt treatment. Treatments include chemotherapy or a donor stem cell transplant.

The only way to cure MDS is to have intensive treatment with a stem cell transplant from a donor. But unfortunately this type of treatment is not suitable for everyone.

Treatments for myelodysplastic syndromes include

Supportive treatment

Supportive treatment aims to help control the symptoms of MDS. The supportive treatment you need will depend on which type of MDS you have. You may need a combination of treatments.

You may have transfusions to treat your MDS. If your red blood cells are low, you have a drip containing red blood cells. If your platelets are low you have a drip of a clear fluid containing platelets.

Having a lot of blood transfusions can cause a build up of iron in your body. Red blood cells contain iron and your body stores this. But too much iron in your body can damage your heart and liver. To stop this, you may need to take drugs to get rid of the excess iron.

Growth factors are drugs that encourage your bone marrow to make more blood cells. We know from research that this can reduce the number of blood transfusions you need. Erythropoetin is a growth factor that increases the number of red blood cells. Granulocyte colony stimulating factor (G-CSF) is a growth factor that increases the number of white blood cells. Which you have depends on your symptoms and blood counts. You have both of these drugs as injections just under the skin (subcutaneously).

You may also need to take antibiotics to treat infections.

Immunosuppression treatment

This is treatment that stops the immune system working. This helps the bone marrow to make blood cells. And it can help to control symptoms and slow down low risk and intermediate risk 1 MDS.

Drugs include anti thymocyte globulin (ATG) and cyclosporin. This treatment is not suitable for everyone. We know from research that it works best in

  • Younger people
  • People with relatively normal blood cell counts
  • People without a chromosome change associated with their MDS

We need more research to find out how best to use this type of treatment.


Chemotherapy uses cell killing (cytotoxic) drugs to destroy the immature cells. The drugs work by disrupting the growth of cells and stopping them from dividing. The type of chemotherapy depends on your type of MDS and your risk group. You may have chemotherapy as a tablet or as an injection into a vein. You may have just one drug or a combination of drugs.

If you have intermediate 2 or high risk MDS you are likely to have chemotherapy similar to that used for acute myeloid leukaemia (AML). You can find more information about these treatments in the chemotherapy for AML section.

The chemotherapy drugs doctors use may include

The National Institute for Health and Care Excellence (NICE) and the Scottish Medicines Consortium have recommended that azacitidine should be available within the NHS for people with MDS, under certain conditions. You must have intermediate risk 2 or high risk MDS and not be able to have high dose treatment with a stem cell transplant.

Intensive treatment with a stem cell transplant

To have a donor stem cell transplant you first have to have your own bone marrow cells destroyed. This means having high dose chemotherapy and sometimes total body radiotherapy. After this treatment you have stem cells from a donor to replace your own bone marrow cells. You have these through a drip into your bloodstream. Usually this is through a central line. The donor is someone whose stem cells match yours. The most suitable donor is usually a close relative such as a brother or sister.

It takes from a few days to a few weeks for the donor stem cells to start making new blood cells. During this time you will need blood and platelet transfusions and are at a high risk of developing infections. So your doctor and nurses will give you antibiotics and anti viral drugs to try to prevent them. You can read more about stem cell transplants in the cancer treatment section.

This treatment is very intense and has risks. You can usually only have this if you

  • Are younger
  • Are in reasonably good health, apart from your MDS
  • Have a suitable donor

If a donor stem cell transplant is an option for you, you will need to talk through all the benefits and risks of this treatment with your specialist.

Newer treatments

Doctors and researchers are looking into a number of other treatments for MDS.

Lenalidomide (Revlimid) is a type of biological therapy. We know from research that lenalidomide can help to control a type of MDS with a particular chromosome change called del5q. We don't fully understand how lenalidomide works. Researchers think it may affect the immune system. Doctors have mainly used it as a treatment for lower risk MDS but research is now also looking at it to treat higher risk MDS.

Researchers are looking at other types of biological therapies for MDS including

  • Panobinostat
  • Vorinostat
  • Ganetespib

Researchers are looking into a drug called decitabine (Dacogen). This is a similar chemotherapy drug to azacitidine. They are also looking at different ways of using azacitidine, including giving it in tablet form rather than as an injection under the skin or as a drip into a vein.

Researchers for the AML LI-1 trial are looking into new chemotherapy drugs called sapacitabine and vosaroxin and a biological therapy called AC220. AC220 is a type of tyrosine kinase inhibitor. The researchers want to find out if these drugs alone or in combination with cytarabine are better than cytarabine on its own for high risk MDS or AML.

You can find information about trials of treatments for myelodysplastic syndromes on our clinical trials database. Type ‘myelodysplastic syndromes’ into the search box. Tick the boxes for closed trials and results if you want to include trials that are no longer recruiting patients.


Coping with MDS

Coping with a rare condition can be difficult, both practically and emotionally. Being well informed about your condition and its treatment can help you to make decisions and cope with what happens.

The symptoms of MDS often mean that you feel less able to do everyday things. Talk to your doctor or nurse about any symptoms you have. There may be supportive treatments that can help you. You may also feel better if you

  • Eat a healthy well balanced diet
  • Do some exercise – after checking with your doctor
  • Rest when you are tired

If you get tired easily, try to work out your priorities each day. Talk to your family and friends and ask for any help you need. You can find tips about coping with tiredness in the section about fatigue and cancer.

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Updated: 26 April 2014