A stem cell transplant is a treatment that is used in many blood cancers, and is often the only cure (as with MDS). About 4,000 are done in the UK in a year, almost as many as kidney, liver, heart and lung transplants combined.
A stem cell donor is needed that is a close match genetically to the patient being treated. Parents and children are guaranteed to be at least a 50% match, and are often appropriate. A sibling can be a 100% match. There are various donor lists, such as the Anthony Nolan, where people have generously signed up to offer themselves as donors. There are international lists and it is not unusual to have a donor from the other side of the world.
Once a donor is identified and various checks have been made, preparation begins.
The donor has a daily injection over a few days that stimulates production of stem cells, which then appear in the donor’s blood. Then there is a day where the donor’s blood is filtered and the stem cells extracted. These can be frozen if needed.
The patient’s preparation starts with chemotherapy to remove as much of the cancerous blood cells as possible. The patient will stop producing blood cells and will need regular transfusion during the treatment. The patient is then given the donor’s stem cells in an infusion, just as if it was a bag of ordinary blood. The stem cells then find their way into the bone marrow and start to produce blood cells.
Within two or three weeks new cells will start to appear in the patient’s blood. It can take a few months before the patient is producing enough cells for their needs, and there will be regular monitoring. In due course the patient will have a completely new system for producing blood.
The main risks after chemotherapy are infection and graft versus host disease. The patient will have no immunity immediately after the chemotherapy, and it will take a long time for it to develop. In this time infections can be very dangerous. After 6 months the patient will have childhood vaccinations. Graft versus host disease is when the new immune system attacks the patient’s organs. There will be careful monitoring for the first year to minimise risk and manage any symptoms.
The patient needs to take great care to avoid infection, particularly in the first six months, but throughout the first year or so.
The above is a very brief explanation, and if you want to read more then there is plenty of information online: NHS, Anthony Nolan,, Cancer Research UK, MDS UK Patient Support Group.