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Myelodysplastic syndrome (MDS) is a blood disorder that causes a drop in your number of healthy blood cells.
Another name for this condition is myelodysplasia.
Normally, bone marrow produces:
In MDS, your bone marrow doesn't make enough healthy red blood cells, white blood cells and/or platelets. Instead, it makes abnormal cells that are not fully developed.
As the condition develops, your bone marrow becomes full of the abnormal blood cells, which spill out into your bloodstream.
MDS can either be indolent (slow developing) or aggressive (rapid developing).
The main types of myelodysplasia are:
"Refractory" means the condition doesn't respond to treatment that doctors would normally use for low blood cell counts.
For most people, symptoms are mild at first and slowly get worse. You may initially experience:
Some types of MDS develop more quickly than others. Some people with MDS don't have any symptoms, and their condition is picked up after they have blood tests for something else.
Symptoms will depend on the type of MDS you have – for example, some people just have a problem with their red blood cells and have symptoms of anaemia, while others may lack all types of healthy blood cell.
MDS can affect people of any age, but is most common in people aged 65-70 years. Only one in five people with MDS are younger than 50.
In most cases, the cause is unknown – this is called primary MDS.
However, exposure to the chemical benzene – used in the rubber industry, and found in petrol – is known to increase your risk of developing MDS.
In rare cases, MDS is caused by radiotherapy or chemotherapy treatment for cancer. This is known as secondary MDS, or treatment-related MDS.
MDS is diagnosed by carrying out blood tests and bone marrow tests. Blood tests will show how many normal and abnormal blood cells you have.
A bone marrow test is done under local anaesthetic, which is injected into the area behind your hip bone. The doctor then passes a needle through your skin and into your bone, drawing out a sample of your bone marrow into a syringe. This will be sent to a laboratory to be examined under a microscope.
The bone marrow test takes 15-20 minutes and can be done on the ward or in the outpatients department.
Some people with MDS go on to develop acute myeloid leukaemia (AML), which is cancer of the white blood cells. This is known as "transformation".
According to Cancer Research UK, the risk varies from five in every 100 cases (5%) to 65 out of every 100 cases (65%), depending on the type of MDS you have. It can take a few months or up to several years before transformation takes place.
Ask your doctor about your risk of developing AML.
Treatment will depend on your type of MDS, your risk group, and whether you have any other health conditions.
The aim is to get the number and type of blood cells in your bloodstream back to normal, and manage symptoms with supportive treatment (see below).
If your MDS has only a low risk of transforming into cancer, you may not need any treatment at first, and may just be monitored with regular blood tests.
Symptoms of MDS can be controlled with a combination of the following treatments:
Drugs such as anti-thymocyte immunoglobulin (ATG) and ciclosporin reduce the activity of the immune system, allowing your bone marrow to make blood cells. It can also help to control symptoms.
However, these drugs are not suitable for everyone and work best in young people and those who don't have a chromosome change associated with their condition.
If you're at a higher risk of developing AML, you will need prompt treatment with chemotherapy or a stem cell transplant (see below).
Chemotherapy involves taking drugs that destroy the immature blood cells by disrupting their growth. The drugs are taken either as a tablet or an injection.
If you have a higher risk of developing AML, your chemotherapy treatment will probably be similar to that used to treat AML. Read about the treatment of AML.
You will probably have one or a combination of the following chemotherapy drugs:
The only way to cure MDS is to have intensive treatment with a stem cell transplant from a donor – but this isn't suitable for everyone.
A stem cell transplant will generally only be offered if you are young and in reasonably good health (apart from your MDS), as it's a very intensive treatment.
It helps if you have a suitable donor in your family (a close relative, such as a brother or sister), although in some cases, it's possible to have a stem cell transplant using an unrelated donor with a matching tissue type.
Treatment involves destroying your own bone marrow cells with chemotherapy and sometimes radiotherapy, before having stem cells from a donor fed into your bloodstream via a drip.
The National Institute for Health and Care Excellence (NICE) recently published new guidelines on a biological therapy called lenalidomide. Biological therapies work by affecting the way your immune system functions.
Lenalidomide can be used to treat MDS in people with a specific genetic mutation, called an isolated deletion 5q cytogenetic abnormality.
This abnormality can lead to severe anaemia, which requires regular blood transfusions.
The treatment of MDS is constantly evolving and new drugs are being tested all the time.
You may be offered the chance to enter a clinical trial. Find out more about:
If you have MDS, your clinical team will pass information about you on to the National Congenital Anomaly and Rare Diseases Registration Service (NCARDRS).
This helps scientists look for better ways to prevent and treat this condition. You can opt out of the register at any time.