The largest randomised study comparing the effect of type of transplant on survival is published Online First in The Lancet Oncology. It reports that patients transplanted with peripheral blood stem cells (PBSC) have no difference in survival compared with patients given bone marrow after ten years. Bone marrow transplants involve the collection of stem cells from the bone marrow. In peripheral blood stem cell transplantation (PBSCT) stem cells are collected from the donor’s blood and this avoids the complications of bone marrow collection such as surgery and anaesthesia.

Earlier studies have had fairly short follow-ups of three to four years. They indicate that PBSC patients experience more severe graft versus host disease (GvHD) in which the donor immune cells attack the tissues of the recipient. However, lower rates of relapse are reported and patients spend less time in hospital. Still, there is little information about the long-term outcomes and late effects of PBSC transplantation compared with bone marrow transplant (BMT).

The European Group for Blood and Marrow Transplantation (EBMT) compares in this study the long-term outcomes of patients ten years after undergoing a marrow or stem-cell transplant. A total of 329 patients with leukaemia were recruited from 42 transplant centres between 1995 and 1999. They were randomly assigned to receive either peripheral blood or bone marrow from a matched sibling donor. The treating transplantation centres completed questionnaires for all patients who survived longer than three years. They analysed long-term events, particularly chronic GvHD, late effects, and secondary cancers.

Findings indicate that overall survival was similar ten years after transplantation:

• 49.1 percent for PBSC recipients
• 56.5 percent for BMT recipients

Despite an increased risk of developing chronic GvHD after PBSCT (PBSCT 73 percent compared to BMT 54% percent), there were more PBSC recipients needing immunosuppressive treatment five years after transplantation (PBSC 26 percent compared to BM 12 percent). However, this did not result in a considerably higher number of deaths, nor did it or affect general health status, return to work, or late events.

A significant finding was the trend towards enhanced leukaemia-free survival and overall survival after BMT in patients with acute leukaemia. However, findings were not statistically significant. Patients with acute lymphoblastic leukaemia (ALL) had a leukaemia-free survival probability at ten years of 28.3 percent after BMT compared with 13.0 percent after PBSCT. In patients with acute myeloid leukaemia (AML) this was 62.3 percent for BMT and 47.1 percent for PBSCT. On the other hand, patients with chronic myeloid leukaemia (CML) had similar results with BMT (40.2 percent) and PBSCT (48.5 percent).

The authors explain: “This update comparing two important stem-cell sources did not find differences in survival after 10-year follow-up. However, subgroup analyses did reveal notable differences in survival in patients with acute leukaemias between those who received allogeneic blood cells and those who received bone marrow, while no differences were seen in patients with CML.”

They say in closing: “Our observations support previous reports that different patient groups might still benefit from transplantation with bone marrow.”

“Long-term outcome and late effects in patients transplanted with mobilised blood or bone marrow: a randomised trial”
Birte Friedrichs, André Tichelli, Andrea Bacigalupo, Nigel H Russell, Tapani Ruutu, Michael Y Shapira, Meral Beksac, Dirk Hasenclever, Gérard Socié, Norbert Schmitz
DOI: 10.1016/S1470-2045(09)70352-3
The Lancet Oncology

Written by Stephanie Brunner (B.A.)