High dose chemotherapy destroys cancer cells, but also damages the stem cells that make blood cells in the bone marrow. So if you need high dose treatment you need a way of replacing the stem cells that have been destroyed. This is called having a stem cell. They are sometimes called stem cell rescue or intensive treatments.
Why you might have a stem cell transplant
Your doctor might recommend intensive treatment to improve the chance of getting a complete response, which is called CR or remission. Remission means that there is no sign of active myeloma.
Stem cell transplants are very intensive treatments, and can cause severe side effects. They are not suitable for everyone. Your specialist will talk through the options with you. Treatment decisions depend on the type and stage of myeloma, and your general health.
What are stem cells?
Stem cells are very early cells made in the bone marrow. Bone marrow is a spongy material that fills the bones.
These stem cells develop into red blood cells, white blood cells and platelets.
Red blood cells contain haemoglobin which carries oxygen around the body. White blood cells are part of your immune system and help to fight infection. Platelets help to clot the blood to prevent bleeding.
You have a stem cell transplant after very high doses of chemotherapy, usually melphalan. The chemotherapy has a good chance of killing the myeloma cells but it also kills the healthy stem cells in your bone marrow.
Before your high dose chemotherapy, your team collects your stem cells. This is called an autologus stem cell transplant. Or rarely, they collect a matched donor's stem cells. This is called an allogenic stem cell transplant.
After the treatment you have the stem cells they collected into a vein through a drip. The cells find their way back to your bone marrow. They begin to make the cells you need after a few days or weeks. This process is called engraftment.
Collecting your stem cells
You have injections of growth factors before, and sometimes after, the stem cell transplant. Growth factors are natural proteins that make the bone marrow produce blood cells.
You have daily injections of growth factor for between 5 and 10 days. Sometimes you might have low doses of chemotherapy with the growth factor injections.
On the collection day
After your growth factor injections, you have blood tests every day to see if there are enough stem cells in your bloodstream. When there are enough cells, your nurse collects them. This is called harvesting. Collecting the stem cells takes 3 or 4 hours. You are awake during this process. You lie down on a couch. Your nurse puts a drip into each of your arms and attaches it to a machine.
Your blood passes out of one drip. It goes through the machine and back into your body through the other drip. The machine filters the stem cells out of your blood. They are collected and frozen until after your high dose treatment.
You might feel very tired after having your stem cell collection.
You might have:
- tingling around your mouth
- muscle cramps
This happens if your calcium level gets low during your collection. Your nurse will give you extra calcium through a drip if this happens.
Having stem cells from a donor
Much more rarely, you might have a stem cell transplant using cells from a donor. This is called an allogeneic transplant. The cells need to be as similar as possible to yours.
So these can be from:
- a brother or sister (a sibling match)
- someone not related to you but whose stem cells are similar to yours (matched unrelated donor)
This is not a common treatment for myeloma.
The side effects of having a stem cell transplant are caused by high dose chemotherapy.
The main side effects include:
- low blood cell counts, causing an increased risk of infection, bleeding and anaemia
- sickness and diarrhoea
- a sore mouth
Some side effects start to get better within a few weeks of your transplant, others can last for much longer, such as fatigue.
If you have stem cells from a donor, there is a risk of them attacking some of your own body cells. This is called graft versus host disease (GvHD).