Donation of either peripheral blood stem cells (PBSCs) or bone marrow (BM) causes no lasting health consequences, according to the largest such study undertaken so far.
In particular, German investigators observed no increased malignancy risk related to PBSC donation.
According to follow-up of more than 12,000 unrelated donors, "the vast majority finds stem cell donation a positive experience that enriched their lives, and they would be willing to donate again," Dr Alexander H. Schmidt said.
Dr Schmidt is from the DKMS German Bone Marrow Donor Centre in Tubingen, the largest in the world.
To determine major health-related events, he and his colleagues mailed questionnaires to 15,456 previous donors. Average follow-up of the 81.3% who responded was 4.2 years (maximum 11 years), equating to more than 55,000 observation years.
Dr Schmidt explained that granulocyte colony stimulating factor is used to mobilise stem cells to the peripheral blood, which has been considered a potential risk factor for haematological malignancies.
Reporting the malignancies
All told, 85 malignancies (standard incidence ratio (SIR), 0.99) were reported: 50 cases among PBSC donors, 31 among BM donors, and 4 among dual donors.
Only six haematological malignancies were reported: two cases of Hodgkin disease (SIR 2.5) and one case of plasmocytoma (SIR 3.6) in PBSC donors; one case each of acute myeloid leukaemia (SIR 1.1) and non-Hodgkin lymphoma (SIR 0.7) in BM donors; and one case of chronic lymphocytic leukaemia in dual donors.
In their meeting abstract, the authors write, "Based on these data, a threefold or stronger increase of the leukaemia risk through PBSC donation can be excluded with an error probability of alpha = 0.05."
More than 90% of responders reported that their health condition was good or very good. Only the dual donors were less likely at 90% to consider donating again, while more than 95% in the other two groups were willing to do so.
Dr Schmidt plans to contact this cohort again in 4 or 5 years to increase the length of follow-up. For now, though, the data indicate that stem cell donation is safe, with no increase in malignancy risk.
"It can't be emphasised enough what a huge thing all these donors are doing. They're complete strangers to the recipients, so donation is a completely altruistic act," Dr Schmidt stressed. "We hope that by further underscoring the safety of the procedure that we will encourage more people to become donors."
(Reuters Health, Karla Gale, December 2010)