Stem Cell Transplant for Acute Myeloid Leukemia

I was curious and thought I'd post what I'd learned about the SCT I will be undergoing in the near future...read on if you are interested as well.

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While very high doses of chemo drugs might work better to kill cancer cells, the damage to the bone marrow could be fatal. A stem cell transplant (SCT) offers a way for doctors to use high doses of chemo. The drugs destroy the patient's bone marrow, but the transplanted stem cells restore it.

Stem cells for a transplant come from either from the blood or from the bone marrow. Bone marrow transplants were more common in the past, but today peripheral blood stem cell transplant (PBSCT) is much more common.

There are 2 main types of stem cell transplants: allogeneic and autologous. The difference is the source of the blood-forming stem cells.

• An allogeneic transplant is the most common form of SCT used to treat acute leukemia. For this, the stem cells come from someone else -- a donor whose tissue is a close match to that of the patient's, often a brother or sister. Sometimes umbilical cord stem cells are used.
• In an autologous transplant, a patient's own stem cells are removed from his or her bone marrow or blood. They are frozen and stored while the person gets treatment with strong chemo and perhaps radiation. The stem cells are then given back to the patient after treatment.

There is a good reason to use stem cells from someone else for the transplant. These cells seem to help fight any remaining leukemia cells through an immune reaction. This is called a "graft-versus-leukemia" reaction and is explained below. Also, the patient’s own stem cells may contain some leukemia cells, even if they are collected when the leukemia is in remission.

The transplant process

The treatment works like this: stem cells are collected from the bloodstream in a process called apheresis. The cells are frozen and stored. Patients are then given very high doses of chemo to kill the cancer cells. They also may get total body radiation to kill any remaining cancer cells. After treatment, the stored stem cells are given to the patient as a blood transfusion. The stem cells settle into the patient's bone marrow over the next several days and start to grow and make new blood cells.

People who get a donor's stem cells are given drugs to prevent rejection as well as other medicines as needed to prevent infections. Usually within a couple of weeks after the stem cells are given they start making new white blood cells. Then they begin making platelets, and finally, red blood cells.

Patients having SCT have to be kept away from germs as much as possible until their white blood cell count is at a safe level. They stay in the hospital until the white cell count reaches a certain number, usually around 1,000. After they go home, they will be seen in the outpatient clinic almost every day for several weeks.

"Mini-transplant"

Most older patients can't have a regular transplant that uses high doses of chemo. Some may be able to have what is called a "mini-transplant" (also called a non-myeloablative transplant or reduced-intensity transplant), where they get lower doses of chemo and radiation that do not destroy the all cells in their bone marrow. They then are given the donor stem cells. These cells enter the body and form a new immune system, which sees the leukemia cells as foreign and attacks them (a "graft-versus-leukemia" effect). Many doctors still think this approach is experimental in AML. Studies are being done to find out how useful it may be against AML.

Some things to keep in mind

Stem cell transplantation is a complex treatment. If the doctors think that a person with leukemia might be helped by this treatment, it is important that it be done at a hospital where the staff has experience. Some transplant programs may not have experience in certain transplants, especially those from unrelated donors.

A stem cell transplant can cost more than $100,000 and may mean a long hospital stay. Because certain types of SCT may be seen as “experimental” by insurance companies, they might not pay for it. You should find out what your insurance will cover and what you might have to pay before deciding on a transplant.

Side effects of stem cell transplant

Side effects from stem cell transplantation can be divided into early and long-term effects. The early side effects are much the same as those caused by any other type of high-dose chemo. One of the most common and serious short-term effects is the greater risk of infection. Antibiotics are often given to try to prevent this. Other side effects, like low red blood cell and platelet counts, may mean the patient will need transfusions.

Long-term side effects: Some side effects can last for a long time and may not even happen until years after the transplant. These long-term side effects can include:

• Graft-versus-host disease (GVHD), which occurs only in a donor (allogeneic) transplant (see below)
• Radiation damage to the lungs, causing shortness of breath
• Damage to the ovaries causing infertility and the loss of menstrual periods (menopause)
• Damage to the thyroid gland that causes problems with changing food into energy
• Damage to the eye that can affect vision (cataracts)
• Bone damage (if damage is bad, the patient may need to have part of the bone and joint replaced)

Graft-versus-host disease (GVHD) is the main problem of a donor stem cell (allogeneic) transplant. It happens when the immune system of the patient is taken over by that of the donor. The donor immune system then starts to attack the patient's other tissues and organs. In severe cases, GVHD can be life-threatening.

Symptoms can include bad skin rashes with itching and severe diarrhea. The liver and lungs may also be damaged. The patient may also be very tired and have aching muscles. If bad enough, GVHD can be fatal. Drugs that weaken the immune system may be given to try to control it. The plus side of graft-versus-host disease is that the donor bone marrow usually kills any remaining leukemia cells. This is called the "graft-versus-leukemia" effect.