A stem cell transplant allows you to have much higher doses of chemotherapy than usual. Very high doses of chemotherapy, sometimes with radiotherapy, are given over a few days. This can help to improve the chances of curing the leukaemia, or prolonging a remission.

Stem cells are blood cells at the very earliest stage of development in the bone marrow. They are mainly collected (harvested) from the blood, but can also be collected from the bone marrow.

High-dose treatment with a stem cell transplant may be of benefit to some people but is not suitable for everyone with acute lymphoblastic leukaemia. High-dose treatment is usually used if the ALL comes back after treatment or if the ALL is a type that is very likely to come back after initial chemotherapy treatment. If your doctor thinks that high-dose treatment is necessary or a possible treatment option for you, they will discuss it with you in detail.

The two main types of transplant are described below:

Your own stem cells, collected either from your blood or from your bone marrow, can be used to allow you to have high doses of chemotherapy. This is sometimes called an autologous transplant or an autograft. But, strictly speaking, only situations where stem cells are taken from someone else are actually transplants. Throughout this section the term high-dose treatment and stem cell support is used, rather than autologous transplant.

High doses of chemotherapy and sometimes whole-body radiotherapy (total body irradiation or TBI) are given to improve the chances of curing leukaemia. The high-dose treatment destroys the cells in your bone marrow. Your own blood stem cells or, less commonly, stem cells from your bone marrow can be used to help ‘rescue’ you from this intensive treatment. Some of your own stem cells are taken and stored before you have high doses of treatment. When the treatment is over, your stem cells are given back to you through a drip into a vein (like a blood transfusion).

For high-dose treatment and stem cell support to be successful it is important that there is no sign of any leukaemia cells in the bone marrow. So high-dose treatment is usually given if the leukaemia has been cleared out of the bone marrow by previous chemotherapy treatment.

Although high-dose treatment and stem cell support is a serious procedure it is less complicated than using stem cells from a donor. There are fewer complications and recovery is faster. It is carried out in many cancer treatment hospitals.

This type of transplant involves having stem cells collected from the blood or bone marrow of another person (a donor). Doctors call this an allogeneic transplant or an allograft.

Treatment with high-dose chemotherapy is given to destroy the cells in your bone marrow. Afterwards, the donated stem cells are given to you. This means that you have a source of healthy bone marrow, which will help you to recover from the effects of your high-dose treatment.

The most suitable donor is usually a brother or sister whose bone marrow is a close match to your own. Occasionally it is possible to use stem cells from an unrelated donor if tests have shown that their white blood cells are a good match with yours.

Donating blood stem cells usually involves one or two outpatient visits. Before the stem cells can be collected a donor will need to have injections of a protein called G-CSF. This encourages the bone marrow to produce lots of stem cells. The stem cells spill over into the blood and can then be collected. It does not cause any harm to the donor. Bone marrow is removed using a general anaesthetic and will involve a short stay in hospital.

Graft versus host disease

When donor stem cells are given there is a risk that they can cause a reaction. For some months after the transplant, your doctors and nurses will be monitoring you carefully for any signs of the new marrow reacting against your own body tissue. This is called graft-versus-host disease (GvHD). It can occur up to six months after your transplant and can cause diarrhoea, rashes and liver damage, but it does not mean that your transplant has failed. Your doctor will prescribe drugs to help prevent the graft reacting against your body.

Graft versus leukaemia

As well as attacking your body’s healthy cells the donor cells can sometimes attack the leukaemia cells. This is called graft-versus-leukaemia.

Risks of an allogeneic transplant

An allogeneic transplant is a serious and complicated procedure. This intensive treatment is carried out in specialised transplant units in specialist hospitals. Although some people have a better chance of curing the leukaemia with high-dose treatment there is also a small risk of dying from the procedure itself.

Information about high-dose treatments

Whichever of the above approaches is taken your doctors and nurses will make sure that you are clear about what is involved. It is a good idea to ask about the possible benefits and risks of the treatment in your situation and ask questions about anything that you do not understand. If you have an allogenic transplant, your donor will also be given information.

High-dose treatment

The first stage is to destroy your own bone marrow completely. This is done with high doses of chemotherapy, often combined with whole-body radiotherapy. The whole-body radiotherapy is usually given either as a single dose lasting over an hour or as eight sessions each lasting about 15 minutes. You may have the treatment lying down or sitting in a supportive chair. If treatment is given as one long session you may be given sedation to help you relax.

The treatments can make you feel extremely ill for a couple of weeks. You may feel very sick and be very weak and tired. You may have other effects such as diarrhoea or a sore mouth. The hospital staff will give you medicines to minimise the side effects. Usually hair falls out completely after high-dose chemotherapy.

Having the bone marrow or stem cells

After the high-dose treatment, the donated bone marrow or stem cells are given through a drip into your vein or through your central line.

The new stem cells, known as a graft, take a few weeks to settle in your bones and produce the blood cells that you need. Because of your low immunity certain precautions will be taken to protect you from infections until your white blood cell count has recovered. You may be looked after in a room of your own (isolation) for several weeks and may be given antibiotics to protect you against infection.

There will be some restrictions to your diet, and family and friends will be asked not to visit you if they have coughs or colds or are unwell. Most hospitals and specialist centres have their own policy on how to look after you during this time. Your doctor or nurse will explain this to you beforehand.

It may take up to a year to recover from high-dose treatment and you will be carefully monitored during this time.

We have a section on stem cell and bone marrow transplants which gives more detailed information.