For your preparative regimen, you will receive high doses of chemotherapy and possibly radiation therapy. This high-dose treatment destroys diseased cells in your body. The treatment also destroys the blood-forming cells in your bone marrow to make room for your new cells and destroys your immune system so it cannot attack your donated cells after the transplant. The doses of chemotherapy and radiation therapy are much higher than would be used to treat the same disease in a patient who was not getting a transplant. While these higher doses may cause more severe side effects, they may also destroy more disease cells.
The preparative regimen may last four to ten days. The length of this treatment depends on your disease, your age, any previous treatments you may have had and whether your disease is active. You may begin your preparative regimen even before you enter the hospital for your transplant.
All preparative regimens use chemotherapy. Some also include radiation to the whole body. This is called total body irradiation (TBI). TBI is used most often for patients with leukemia, lymphoma or myeloma. A single TBI treatment lasts from 10 to 20 minutes. TBI treatments may happen all in one day, or they may be spread out for up to 7 days, depending on the total dose you will receive.