In 1998, there were approximately 37,000 autologous bone marrow transplants and 17,000 allogeneic transplants worldwide, according to the International Bone Marrow Transplant Registry. FDA reviews devices used in the collection, processing, purging and storage of stem cell products. In July 1999, FDA approved two cell separation devices that can select stem cells and decrease the number of cancerous cells that may be inadvertently re-infused into a transplanted recipient. Cell separation devices allow doctors to separate healthy stem cells from tumor cells. Bone marrow is certainly important, Jones says, but so is the chemotherapy or radiation treatment that precedes a transplant.
Therapy destroys cancer cells and defective marrow and makes room for new marrow.
The anti-cancer drugs used for chemotherapy depend on the protocol of the treatment center and the type and stage of disease, but busulfan and cyclophosphamide are the most common. In February 1999, FDA approved an injectable form of busulfan. Because side effects include severe nausea and vomiting, M. D. Anderson's Mullen says some researchers are rethinking the basic approach to transplants as it was laid out 30 years ago. Now some are asking whether such toxic doses are really necessary. He adds that some transplants in the adult program at the Anderson Center have been effective with lower doses of chemotherapy than were previously thought necessary.