Adults with leukemia and other cancers of the blood can use umbilical cord blood from unrelated donors to rebuild their blood systems. Cord blood grafts have been used to treat children since the late 1980s, but doctors have advised against using cord blood transplants as a source of stem cells, immature cells that develop into the various types of blood cells, for adults.

Most oncologists specializing in this area believed that cord blood, especially from unrelated donors, did not contain enough stem cells to create a successful graft in an adult. A study published in the New England Journal of Medicine (Vol. 344, No. 24: 1815-1822) says the conventional wisdom is wrong.

"Out of every 10 adults who needs a stem cell transplant because of cancer or some other disease, only two have a brother or a sister who are perfect donor matches," lead author Mary Laughlin, MD, tells ACS News Today. "The other eight must search for donors. Between 3,000 and 5,000 adults die every year in the US because they can’t find donors. Now we know that even if you can’t find a perfect bone marrow donor, umbilical cord blood can provide a successful graft." Laughlin is director of the bone marrow transplant program at University Hospitals of Cleveland and Case Western Reserve University.

Advanced cancers of the blood and other tissues are sometimes treated by destroying the patient’s bone marrow with radiation or intensive chemotherapy. Killing blood-producing marrow kills the cancer, but patients need a graft of new, healthy stem cells. Doctors prefer to graft bone marrow from an adult donor, which is rich in stem cells, taken from a close relative in order to reduce graft versus host disease (GVHD — when the donor cells recognize the recipient’s body as foreign).

The graft may attack certain organs, impairing their ability to function and increasing susceptibility to infection. The organs usually affected are the skin, gastrointestinal (GI) tract, and liver. The closer the genetic match, the lower the risk of acute GVHD, which can be fatal.

"This is the first study to show that umbilical cord blood can be used to transplant adults," said Chris Hillyer, MD, a hematologist and director of the blood bank and transfusion service unit at Emory University in Atlanta. "What this means is that even if you can’t find a matched bone marrow donor, you still have a good chance at a successful transplant."

Laughlin and researchers at four other transplant centers used frozen umbilical cord blood to transplant 68 adults whose bone marrow had been destroyed by full-body irradiation or intensive chemotherapy. All of the patients were in serious condition and 54 had failed prior treatment for leukemia or other blood-related cancers.

Of the 68 patients, 66 received blood that was mismatched because matching grafts were not available. Despite their frail state of health, 19 of the patients were still alive 40 months after the transplant and 18 remained disease-free.

The risk of chronic GVHD was just 38% in the study. That compares to GVHD rates of up to 75% for patients who receive matched bone marrow transplants from unrelated donors.

"Survival doesn’t seem to be affected by receiving a cord blood graft from an unrelated and mismatched donor," said Herman Kattlove, MD, medical oncologist and medical editor at the American Cancer Society. "This can be life-saving for patients who can’t find a matching graft."

Finding a matched graft is harder for some patients than others. Laughlin said that about 50% of white patients eventually find matching bone marrow, but fewer than 15% of Asian, Hispanic, black, and other non-white patients are successful in their search because of low donation rates in minority communities. Grafting umbilical cord blood gives all patients access to stem cell transplants regardless of bone marrow donation rates.