Stem cell transplants are used to replace bone marrow that has been destroyed by disease, chemo, or radiation. In some diseases, like leukemia, aplastic anemia, certain inherited blood diseases, and some diseases of the immune system, the stem cells in the bone marrow don’t work the way they should.
Damaged or diseased stem cells can make too few blood cells, too few immune cells, or too many abnormal cells. Any of these problems can cause the body to not have enough normal red blood cells, white blood cells, or platelets. A stem cell transplant may help correct these problems.
In some cancers, such as certain leukemias, multiple myeloma, and some lymphomas, a stem cell transplant can be an important part of treatment. It works like this: high doses of chemo or radiation work better than standard doses to kill cancer cells. But high doses can also cause the bone marrow to completely stop making blood cells, which we need to live. This is where stem cell transplants come in. They replace the body’s source of blood cells after the bone marrow and its stem cells have been destroyed by the treatment. The rescue transplant lets doctors use much higher doses of chemo or radiation to try to kill all of the cancer cells.
Stem cell transplants from another person can also help treat certain types of cancer in a different way other than just replacing stem cells. The donated cells can often find and kill cancer cells better than the immune cells of the person who had the cancer ever could. This is called the “graft- versus-cancer” or “graft-versus-leukemia” effect. It means that certain kinds of transplants actually help fight the cancer cells, rather than simply replacing the blood cells.
Making the decision to have a transplant is not easy. The cancer care team must compare the risks linked with the cancer itself versus the risks of the transplant procedure. Transplant risks are serious, and the patient could die from complications. The stage of the disease, patient’s age, time from diagnosis to transplant, donor type, and the patient’s overall health are all part of weighing the pros and cons before making the decision.