Unrelated volunteer bone marrow transplantation: initial experience at St Vincent's Hospital, Sydney.

Background: Only 30% of patients with leukaemia have an HLA-compatible family member able to act as a marrow donor. The recent development of volunteer bone marrow donor registries has supplied HLA-matched donors for a number of such individuals.

Aims: To define the problem and outcome of the first cohort of patients given HLA-matched unrelated volunteer bone marrow transplants at St Vincent's Hospital, Sydney.

Methods: Post transplant outcome of patients with advanced leukaemia given HLA-identical unrelated donor marrow transplants was compared to that of patients transplanted concurrently from HLA-identical sibling donors, in terms of survival, leukaemia-free survival, incidence and severity of acute graft-versus-host disease (GVHD), duration of neutropenia, incidence of infection and duration of transplant hospitalisation.

Results: Sixteen patients with advanced leukaemia and without a histocompatible family member donor received unrelated donor bone marrow transplants. Actuarial survival at two years post transplant was 30%. Actuarial survival of 23 recipients of HLA-identical sibling bone marrow transplants with advanced leukaemia transplanted during the same time period was 17% (not significant). Actuarial disease free survival at two years was 30% and 13% respectively. Three of five long term survivors of the unrelated transplants had chronic myeloid leukaemia in blastic transformation at the time of transplant; thus blastic transformation should not preclude consideration of unrelated marrow transplantation. Recipients of unrelated allografts had a higher incidence of acute GVHD which occurred earlier and with greater severity than in recipients of sibling allografts, a longer duration of post transplant neutropenia (24 days to reach 0.5 x 10(9)/L versus 19.5, p = 0.07), a higher frequency of infection in the first 100 days post transplant (p = 0.0004) and a longer duration of transplant hospitalisation (p = 0.04). Transplant-related complications were the commonest cause of death in the unrelated donor recipients, while leukaemic recurrence was the commonest single cause of death in the HLA-identical sibling recipients. Improvements are needed in prophylaxis of infection and in prevention and treatment of acute GVHD in recipients of unrelated donor transplants. Nevertheless, this modality provides curative treatment for patients with otherwise incurable haematological malignancies and should no longer be considered experimental.