What are stem cells and what is a stem cell transplant?
Your body constantly makes new blood cells.
- White blood cells fight infection as part of your immune system.
- Red blood cells carry oxygen around your body.
- Platelets help your blood to clot, preventing bruising and bleeding.
Blood cells are made from blood stem cells in your bone marrow (the spongy tissue in the centre of your bones).
Chemotherapy causes temporary damage to the bone marrow. This can cause low blood counts, eg neutropenia (low neutrophils), anaemia (low red blood cells) and thrombocytopenia (low platelets). Cycles of chemotherapy usually include rest periods so your bone marrow can recover between treatments.
Some people need high doses of chemotherapy to treat their lymphoma. High doses of chemotherapy can be very effective at killing lymphoma cells but they can cause permanent damage to your bone marrow.
You can be given healthy blood stem cells after high-dose chemotherapy – this is called a stem cell transplant. You can then make the new blood cells that your body needs. The stem cells can be your own stem cells (an autologous stem cell transplant) or they can be from a donor (an allogeneic stem cell transplant). If you are given donor stem cells, these can also form a new immune system that can recognise and fight lymphoma.
Stem cell transplants are used in different situations but mainly when:
- your lymphoma has relapsed (come back) after treatment
- your lymphoma is refractory (doesn’t respond) to treatment
- as part of your first treatment if your doctor thinks your lymphoma is likely to relapse.
A stem cell transplant is an intensive form of treatment and you have to be fit enough to have it.
An ‘autologous’ stem cell transplant uses your own stem cells. An ‘allogeneic’ stem cell transplant uses stem cells from a donor (someone else).
In an autologous stem cell transplant, your own stem cells are collected before your high-dose treatment. Then the stem cells are frozen, stored and given back to you after your high-dose treatment. This kind of treatment is sometimes called ‘high-dose therapy and stem cell support’ or ‘high-dose therapy and stem cell rescue’.
In an allogeneic stem cell transplant, you are given donor stem cells after your high-dose treatment. In an allogeneic transplant the donor stem cells give you a new immune system as well as help your bone marrow to recover from chemotherapy. The new immune system can kill your lymphoma cells.
Both types of transplant can increase your chance of a long-lasting remission from lymphoma (no evidence of the disease), but the risk of relapse may be lower with an allogeneic stem cell transplant.
An allogeneic stem cell transplant has more risks than an autologous stem cell transplant, including higher risk of infection; the possibility of rejection of the donor cells; the donor cells attacking your healthy tissues.