what happens in a stem cell transplant?

Your treatment happens in four stages.

  • Step 1 - Having the chemo or radiotherapy to shrink the tumour or to put you in remission.
  • Step 2 - Having healthy stem cells collected from you or from a donor.
  • Step 3 - Having the high-dose chemo or radiotherapy. This part of the treatment is also called conditioning.
  • Step 4 - Having the stem cells through a drip.

step 1: chemo or radiotherapy

You might have already had this lot of treatment (or you may be having it now). It's the treatment you're given when you are first diagnosed to try and control the cancer. Normally you will have the high dose treatment once your scans and tests show that the cancer has all, or mostly, been destroyed. You could have anything from about 2 to about 6 cycles of chemo before it's time to have the high dose treatment.


step 2: harvesting

autologous transplant

In step 1, your bone marrow is temporarily wiped out by the chemo and takes about 3 weeks to recover. You don't usually start the next cycle of chemo until the marrow has recovered. At some point during this time, you'll have injections of a growth factor medicine called GCSF. It's a once daily injection, just under the skin for ten days. GCSF stimulates your bone marrow to recover quicker and make large numbers of healthy stem cells. When the marrow is full of cells, they spill over into the blood and then they can be collected from you. Collection of stem cells is called harvesting.

You'll have regular blood tests to check if there are enough stem cells in your blood to harvest. The harvest is likely to happen in a day care unit and takes about 3-4 hours. You have a needle (drip) in each arm and blood is taken from one arm, through the drip, into a machine called a cell separator, which 'spins' it to separate out the stem cells. These are collected and the rest of the blood goes back into your body through the drip in your other arm. Having the harvest isn't painful or uncomfortable, though you might get quite bored, so take some music or something to read with you. While you're attached to the machine, you won't be able to get up to go to the toilet so your nurse will bring a bottle or bedpan for you to use.

You may wonder why you need to have needles put in each arm to collect the stem cells when you have a central line. It's because most people get infections in their line regularly. The line must have had no infections for at least three months for it to be used in harvesting but in most cases this is highly unlikely.

The stem cells are frozen and stored until you need them after the high-dose treatment. This means you have a source of healthy stem cells that will eventually become mature, effective blood cells to help you recover from the high-dose chemo.

Sometimes not enough cells are collected in one session so you might have to do it again the next day.

allogeneic transplant (from a donor)

In certain conditions such as leukaemia, it's better to use stem cells from a donor rather than your own. The most suitable donor would be a brother, sister or occasionally a parent whose stem cells are a close match to yours. If this isn't possible, then cells can be used from someone who's not related to you as long as their white cells are a good match to yours. It won't be a perfect match, but it will be a close one. This kind of donor is called an unrelated donor. Donors are volunteers, a bit like people who give blood, and their details are kept on a register. Unfortunately, it can be difficult and it might take a long time to find a good match for you. You might hear your nurses and doctors talking about tissue typing. This is the group of tests that are done on the donor's blood to check that they are a good match. So the different types of allogeneic transplant you could have are:

  • sibling allograft - match from a brother or sister
  • matched unrelated donor (MUD) allograft - match from an unrelated donor
  • mismatched transplant - a close match with very small differences. This is still safe for you to have.

The donor will have GCSF injections for about 5 days before they go to the hospital as an outpatient to donate their stem cells. If the donor is younger than 16 years old, they will have a bone marrow harvest under general anaesthetic.


step 3: high-dose treatment (conditioning)

Once the stem cells have been collected you can have the high-dose treatment. This treatment is high doses of chemotherapy with or without radiotherapy.

You will have much higher doses of chemo than you've had before to try and get rid of any cancer cells that are left in your body. You'll have the chemo over a few days and you might have it in tablet form as well as through a drip. While you're having it, you probably won't feel much different from the other times when you've had chemo. Some people can feel quite sick, though and you'll be given anti-sickness medicines to help with this.

You might also have radiotherapy as part of your high-dose treatment. It's used to kill cancer cells in places that the chemo can't fully reach, like the brain, the ovaries and the testicles. You could also have radiotherapy to all of the bone marrow in your body. This is called total body irradiation (TBI). You're likely to have this if you have leukaemia. It completely wipes out your bone marrow, which helps to prepare your body to receive the healthy, new stem cells.

what does it involve?

If you're having radiotherapy as part of your high-dose treatment then you'll go to the hospital for a planning session a few days before treatment begins. There's more about what this involves in the section about radiotherapy. TBI is usually given in about 6-8 sessions lasting 40 minutes each, twice a day.

The chemo is usually given over a few days. You'll probably feel a bit wiped out by this and won't have much energy so you might choose to have fewer visitors during this time.

side effects

The side effects of high dose treatment are the same as with standard dose chemo except they are worse. It's important to talk these through with your doctors and nurses so that you understand what might happen. These are the main side effects that can happen:

TBI gives a dose of radiation to each part of the body. The main problem is usually feeling sick (nausea). This can be during the treatment itself and you'll be given anti-sickness drugs before your treatment to try and stop this. But you may also have diarrhoea, a sore mouth and jaw and feel very tired.

There are a few different medicines that can be given to reduce some of these side effects and make you feel more comfortable.


step 4: having the stem cells

About a day or two after the intensive chemo and/or radiotherapy is finished, the cells are given back to you through your central line.

The stem cells will have been frozen in small plastic bags with a preservative. The nurse will defrost the cells in a special water bath in your room and put them through your line like platelets. You may have to have 4 to 6 bags and this can take about an hour or so. The preservative gives people a bad taste so you should suck strong flavoured sweets or ice lollies. It also has a strong metallic or sweet corn smell. You won't be able to smell it but other people will. Some people can have reactions to the preservative so your nurse will keep a close eye on your blood pressure, temperature and pulse with every bag you have.


Last reviewed: 04/09/2007