Donation of peripheral blood stem cells (PBSCs), which are stem cells found in the bloodstream, requires the application of filgrastim or similar drugs in order to mobilize the stem cells from the bone marrow to the bloodstream. Some long-term safety issues related to the use of filgrastim, including a potentially increased risk to the donor of developing leukaemia, have previously been raised in the scientific literature. Past research has not extensively addressed long-term bone marrow donor safety issues. In order to further minimize risks for volunteer donors, it is therefore extremely important to determine whether the procedures in which both PBSCs and bone marrow are collected are safe.

Researchers from the DKMS German Bone Marrow Donor Center, the largest bone marrow donation center in the world, set out to determine if there were any long-term risks of developing cancer following the donation of PBSCs or bone marrow through a follow-up questionnaire sent to 15,456 donors. They presented their findings at the American Society of Haematology (ASH) annual meeting and Exposition held December 4-7, 2010 in Orlando, Florida.

In the survey, four main questions were asked about the overall general health of the donor: whether the donor underwent hospitalization or long-term medical treatment for any condition following the donation, whether the donor needed to take any prescription drugs for more than four weeks after the donation, and whether the donor would be interested in donating PBSCs or bone marrow again.

Results from this retrospective study, the largest ever in terms of length of cumulative observation years, revealed that unrelated PBSC and bone marrow donation are safe procedures that do not carry any increased risk to the donor of developing cancer as compared with the general population.

A total of 81.3 percent of the contacted donors sent back completed surveys (12,559 out of 15,456), translating into a total of 55,228 observation years (30,777 observation years for 8,730 PBSC donors, 23,037 observation years for 3,556 bone marrow donors, and 1,414 observation years for 273 donors of both PBSCs and bone marrow). A large majority of donors indicated that their overall health was very good or good (95.1 percent of PBSC donors, 96 percent of bone marrow donors, and 92.2 percent of dual donors). Furthermore, an overwhelming majority also indicated that they would undergo the donation procedure again, with 95.4 percent of PBSC donors and 95.9 percent of bone marrow donors indicating willingness.

Regarding the incidence of cancer in these donors, a total of 85 malignancies were reported, which included 50 cases in 8,730 PBSC donors, 31 cases in 23,037 bone marrow donors, and four cases in 1,414 dual donors. With regard to hematologic malignancies, only six cases were reported, including two cases of Hodgkin disease and one case of plasmocytoma in PBSC donors, one case of acute myeloid leukaemia and one case of non-Hodgkin lymphoma in bone marrow donors, and one case of chronic lymphocytic leukaemia in dual donors.

"Results of this study provide the best evidence we have so far that there is not a higher incidence of cancer associated with the donation of unrelated peripheral blood stem cells and bone marrow as compared with the general population," said lead study author Alexander H. Schmidt, MD, PhD, DKMS German Bone Marrow Donor Center. "We hope that these results underscore the fact that these donation procedures are extremely safe and will encourage more people to become donors."


Source: ASH