In GVHD, certain white blood cells in the donor's bone marrow called T-cells perceive the patient's body as foreign material. They attack organs and tissues in the patient's body, impairing their ability to function properly and increasing the risk of infection. Timing of BMT Long-term leukemia free survival is achieved by approximately 50 to 70 percent of CML patients who undergo a BMT in the chronic phase using marrow from a related donor, and 20 to 60 percent of those using marrow from an unrelated donor marrow. Those who are transplanted in the chronic phase and within a year of their initial diagnosis fare better than those transplanted later. Patients who receive marrow from a matched related donor fare better than those transplanted with marrow from an unrelated or mismatched donor, due to the higher incidence of GVHD and infections in unrelated and mismatched transplants.
Younger patients are better able to withstand the rigors of an allogeneic BMT than older patients.
There is controversy over whether CML patients who have a matched sibling donor should be treated with alpha-interferon in the chronic phase of CML or immediately undergo a bone marrow transplant. For this reason, most BMT centers recommend that CML patients under the age of 50 who have a matched sibling bone marrow donor undergo an allogeneic BMT as soon as possible. Twenty to 40 percent of patients who undergo an allogeneic BMT during the accelerated phase of CML survive long-term. Historically, those who relapsed into a chronic stage of the disease survived 3 to 6 years. Those who relapsed into blast crisis typically survived less than 6 months.