The doses of chemotherapy (chemo) drugs (and radiation) doctors can give are limited by the side effects they can cause. Higher doses can’t be used, even if they might kill more cancer cells, because they would severely damage the bone marrow, where new blood cells are made. This could lead to life-threatening infections, bleeding, and other problems due to low blood cell counts. Doctors can try to get around this problem by giving an infusion of blood-forming stem cells after treatment. These stem cells settle in the bone marrow, where they can create new blood cells.
A stem cell transplant (SCT) is not a common treatment for Waldenstrom macroglobulinemia (WM), but it might be an option in younger patients for whom other treatments are no longer working.
Blood-forming stem cells used for a transplant come either from the blood or from the bone marrow. Bone marrow transplants were more common in the past, but they have largely been replaced by stem cells taken from the blood.
The blood-forming stem cells can come either from the patient (called an autologous SCT) or from a donor (called an allogeneic SCT).
Autologous stem cell transplant
Most transplants in people with WM are autologous. The patient’s own blood-forming stem cells are removed from their bloodstream and stored to use later. Then the patient is given high doses of chemo (and sometimes radiation) to kill the WM cells. The high doses of chemo kill the normal bone marrow cells as well as the cancer cells. After chemo, the frozen stem cells are thawed and returned to the body (like a blood transfusion).
Autologous transplants can help some people with WM, but doctors are still trying to figure out which patients will benefit the most.
Allogeneic stem cell transplant
This is a treatment that is still being studied for WM, and experts recommend it be done only as part of a clinical trial.
In an allogeneic SCT, the stem cells for the transplant come from someone else (a donor). 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 cells.
The stem cells for an allogeneic SCT are usually collected from a donor’s bone marrow or blood on several occasions. Regardless of the source, the stem cells are then frozen and stored until they are needed for the transplant.
Allogeneic transplants have more risks and side effects than autologous transplants, so patients typically need to be younger and relatively healthy to be good candidates. Another challenge is that it can sometimes be difficult to find a matched donor.
One of the most serious complications of allogeneic SCTs is known as graft-versus-host disease (GVHD). It happens when the patient’s immune system is taken over by that of the donor. When this happens, the donor immune system may consider the patient’s own body tissues to be foreign and attacks them.
Symptoms of GVHD can include severe skin rashes, itching, mouth sores (which can affect eating), nausea, and severe diarrhea. Liver damage can cause yellowing of the skin and eyes (jaundice). The lungs can also be damaged. The patient may also become easily tired and develop muscle aches. Sometimes GVHD can become disabling, and if it is severe enough, it can be life-threatening.
Non-myeloablative transplant: In this newer approach to allogeneic SCT (also called a mini-transplant), lower doses of chemo or radiation therapy are used than in a traditional allogeneic SCT. Patients are given drugs to suppress their immune system. This allows the donor cells to grow and partly take over the patient’s immune system. The donor cells then begin attacking the WM cells (known as a graft-versus-lymphoma effect).
This type of transplant may be an option for some patients who couldn’t tolerate a regular allogeneic transplant because it would be too toxic. Most of the side effects with this type of transplant are less severe than with a standard allogeneic transplant. But this type of transplant can still cause GVHD, which can make patients very sick.
Doctors are trying to refine this treatment to work against the WM cells without affecting the normal cells.
Possible side effects of stem cell transplant
Side effects from a stem cell transplant are generally divided into early and long-term effects.
Early or short-term effects: The early complications and side effects are basically the same as those caused by any other type chemotherapy, but they tend to be more severe.
One of the most common and serious short-term effects is the increased risk of infection. Antibiotics are often given to try to keep this from happening. Other side effects, like low red blood cell and platelet counts, may require blood product transfusions or other treatments.
A possible side effect of allogeneic transplants is graft-versus-host disease, which is described above.
Long-term side effects: Some complications and side effects can remain for a long time or might not occur until months or years after the transplant. These include:
- Loss of fertility
- Damage to the thyroid gland
- Cataracts (damage to the lens of the eye)
- Damage to the lungs, causing shortness of breath
- Bone damage called aseptic necrosis (If damage is severe, the patient might need to have part of the affected bone and the joint replaced.)
- Development of another cancer (such as leukemia) years later
Things to consider before having a stem cell transplant
A stem cell transplant is a complex treatment that can cause life-threatening side effects because of the high doses of chemotherapy used. Be sure you understand the possible benefits and risks. If the doctors think you might benefit from a transplant, it should be done at a hospital where the staff has experience with the procedure and with managing the recovery. Some stem cell transplant programs might not have experience in certain types of transplants, especially transplants from unrelated donors.
SCTs often require a long hospital stay and can be very expensive (costing well over $100,000). Because some insurance companies might view it as an experimental treatment, they might not pay for it. Even if the transplant is covered by your insurance, your co-pays or other costs could easily amount to tens of thousands of dollars. Find out what your insurer will cover before deciding on a transplant so you will have an idea of what you might have to pay.