No Health Risk to Unrelated Volunteer Stem Cell Donors

Zosia Chustecka

December 07, 2010

December 7, 2010 (Orlando, Florida) — There appears to be no risk to health from the volunteer donation of peripheral blood stem cells (PBSC) or bone marrow (BM), according to data from the largest donor center in the world. Follow-up on 12,559 unrelated donors did not flag any health issues, German researchers reported here at the American Society of Hematology (ASH) 52nd Annual Meeting.

Unrelated volunteer donation of hematopoietic stem cells is "a purely altruistic act" and is a unique event in the world of medicine, said lead author Alexander Schmidt, MD, PhD, from the DKMS German Bone Marrow Donor Center in Tubingen, Germany.

These are healthy people who volunteer to donate stem cells to help patients with leukemia and lymphoma, for whom a transplant of such cells can be curative in many cases.

Dr. Schmidt emphasized that volunteers are not paid for their donation, although expenses and days lost from work are covered. Donation of BM involves surgery under general anesthesia with a stay in the hospital, and donation of PBSC involves pretreatment with granulocyte-colony stimulating factor (G-CSF) for 5 days to mobilize the stem cells followed by a dialysis procedure, he explained.

There has been concern expressed in the literature that G-CSF therapy might increase the risk for leukemia, he noted.

These results underscore the fact that these donation procedures are extremely safe.

The new data show no increase in any cancers among the donors, compared with the general population. In addition, a large majority of the donors reported that their health was good or very good (95% of PBSC donors, 96% of BM donors, and 92.2% of dual donors).

"We hope that these results underscore the fact that these donation procedures are extremely safe," Dr. Schmidt explained. "We also hope that the new data will also encourage more people to become donors."

Important Study

"There's always been a hesitation over this, particularly among individuals who are donating to strangers, with some concern about 'What's going to happen to me?' " ASH secretary Charles Abrams, MD, associate chief of the Division of Hematology/Oncology at the University of Pennsylvania in Philadelphia, told Medscape Medical News.

There is not much to fear from being a donor.

The informed consent forms that these individuals sign list a great many potential risks and possibilities of what might happen, but this follow-up of thousands of donors shows that "they really do great, and there is not much to fear from being a donor," he said.

"This is a very nice study," Dr. Abrams noted, adding: "I do think this is material that is worth disseminating."

These data are reassuring.

Agreeing with this sentiment was Armand Keating MD, vice-president of ASH, and professor of medicine and director of the Division of Hematology at the University of Toronto, in Ontario. "These data are reassuring and they are important, because they come from the largest cohort of donors that we are ever likely to have," he told Medscape Medical News.

Largest Donor Center in the World

The DKMS German Bone Marrow Donor Center is the largest in the world, having processed 2.3 million donors to date. From 1997 to 2007, this center provided 30.2% of all unrelated PBSC donations and 10.4% of all unrelated BM donations worldwide.

For the current study, Dr. Schmidt and colleagues contacted more than 15,000 past donors and asked them to complete a questionnaire. They obtained responses from 12,559 donors, of whom 8,730 had donated PBSC, 3,556 had donated BM, and 273 had donated both. The median follow-up was 4 years, so these data amount to 55,229 observation years, Dr. Schmidt pointed out.

The questionnaire was deliberately kept simple, he said, and asked only 4 questions: their general health status, any hospitalization or long-term medical treatment since donation, prescription drugs, and willingness to donate again.

There was no indication that the risk of developing cancer among these donors was any different from that in the general population, the researchers report. The only anomaly was an apparent increase in malignant melanoma rates among BM donors, but because there is no plausible biologic explanation for this, this was considered to be a statistical error, Dr. Schmidt said.

Specifically, there was no increased incidence in hematological malignancies between donors and age- and sex-adjusted incidences in the German general population; this includes leukemia, non-Hodgkin's lymphoma, plasmacytoma, and Hodgkin's disease.

Interestingly, the rates for lung cancer and for malignant neoplasm of the lips, oral cavity, and pharynx were lower among donors than among the general population. Because these cancers are associated with a lack of health-conscious behavior, this observation suggests that donors are more health conscious than the general population, Dr. Schmidt explained.

An overwhelming majority of donors indicated that they would be happy to donate again (95.4% of PBSC donors and 95.9% of BM donors).

"In summary, we found no evidence that PBSC or BM donation might be unsafe procedures," the German researchers conclude.

Dr. Schmidt and colleagues have disclosed no relevant financial relationships.

American Society of Hematology (ASH) 52nd Annual Meeting: Abstract 365. Presented December 6, 2010.