Bone Marrow transplants and stem cells can help to treat Leukemia and can sometimes cure the Leukemia but there's no guarantee that it will cure the Leukemia but most times it does.
Before getting a bone marrow transplant or stem cell treatment the patient first gets Chemo Therapy to kill off the unhealthy cells which can be done with or without radiation.
Then the Bone Marrow Transplant or Stem Cell Transplant happens after the Chemo.