Complications From Transplants Using Donor Stem Cells continued...
Graft failure, a rare complication, happens when your immune system rejects the donor's stem cells. If more donor stem cells are available, it can be treated with a second transplant, or with an infusion of residual lymphocytes -- a type of white blood cell -- from the donor.
A relapse of cancer is possible even years after your transplant. Most often, relapses happen because chemotherapy and radiation failed to kill all the cancer cells. Relapses can also occur if there were still cancer cells left in the blood collected before you had chemotherapy. With some aggressive cancers, the relapse rate after a transplant with your own cells may be as high as 50%.
Fortunately, "graft vs. tumor" effect may help prevent relapse. This good benefit occurs when the donor's mature immune cells recognize and attack any cancer cells found in your body after the transplant. To boost this effect, your doctor may want to give you an infusion of donor immune cells along with the donor stem cells. If a relapse does occur, it can be treated with a different chemotherapy regimen, a second transplant (if your own stem cells were used the first time, you may use a donor's cells), or both.