Standard doses of chemotherapy aren’t always able to cure acute lymphocytic leukemia (ALL). Even though higher doses of chemo drugs might be more effective, they are not given because they could lead to long-term severe bone marrow damage. Because the bone marrow is where new blood cells are formed, this could lead to life-threatening infections, bleeding, and other problems due to low blood cell counts.
A stem cell transplant (SCT) allows doctors to use higher doses of chemo (sometimes along with radiation) to kill the cancer cells. After these treatments are finished, the patient receives a transplant of blood-forming stem cells to restore the bone marrow.
Blood-forming stem cells used for a transplant are obtained either from the blood (for a peripheral blood stem cell transplant, or PBSCT), from the bone marrow (for a bone marrow transplant, or BMT), or from umbilical cord blood. Most often, stem cells from the blood are used.
Types of transplants
There are 2 main types of stem cell transplants:
- Allogeneic stem cell transplant – in which the stem cells come from someone else. This is the preferred type of transplant in treating ALL.
- Autologous stem cell transplant – in which the patient gets back his or her own cells
For an allogeneic transplant, the donor’s tissue type (also known as the HLA type) needs to match the patient’s tissue type as closely as possible to help prevent the risk of major problems with the transplant. Usually this donor is a brother or sister if they have the same tissue type as the patient. If there are no siblings with a good match, the cells may come from an HLA-matched, unrelated donor – a stranger who has volunteered to donate their cells. Some patients cannot have this kind of transplant because a matching donor isn’t available. The use of allogeneic transplant is also limited by its side effects, which are often too severe for people who are older or who have other health problems.
One option that may help patients who can’t have an allogeneic transplant because of age or health issues is to have a stem cell transplant that uses lower doses of chemo and radiation that don’t completely destroy the cells in their bone marrow. This is known as a non-myeloablative or reduced- intensity transplant. This kind of stem cell transplant relies on the donor cells to kill the leukemia cells, instead of the chemo and radiation. This is not a standard treatment for ALL, and is being studied to determine how useful it may be.
An autologous transplant may be an option for patients who can’t have an allogeneic transplant because they don’t have a matched donor. The trouble with this is that leukemia is a disease of the bone marrow and blood, so there is a danger of giving the patient back leukemia cells with the stem cells. A process called purging may be done in the lab to try to remove leukemia cells in the samples and lower this risk.
Bone marrow or peripheral blood SCT is a complex treatment that can cause life-threatening side effects. If your doctor thinks you might benefit from a transplant, you should discuss what kind you will have, the possible side effects, and how long it may take for you to recover. Stem cell transplants should be done at a hospital where the staff has experience with the procedure and with managing the recovery phase. Some bone marrow transplant programs may not have experience in certain types of transplants, especially transplants from unrelated or mismatched donors.
For more information on stem cell transplants, see Stem Cell Transplant (Peripheral Blood, Bone Marrow, and Cord Blood Transplants).
Last Revised: 02/18/2016