Bone marrow transplants are used to replace a patient’s damaged bone marrow with healthy marrow obtained from a donor. Bone marrow is the soft inner component of bones. It contains stem cells that produce red blood cells, white blood cells and platelets, as well as more developed precursors of these cells.

Healthy bone marrow is essential to the body’s ability to fight infections, prevent bleeding and carry oxygen to tissues. Bone marrow transplants may be performed in cancer patients to directly attack and kill cancer cells. However, they are most often used to restore bone marrow function that has been compromised by other cancer treatments, such as chemotherapy and radiation. Bone marrow transplants are not usually considered for a cancer patient unless there is evidence the patient will have a significant response to the other cancer treatments being contemplated.

The bone marrow used in a transplant procedure is sometimes obtained from patients themselves. In other cases, healthy marrow may be donated by an identical twin, another family member or someone unrelated to the patient.

Before the transplant, a surgical procedure is used to harvest stem cells from the donor’s bone marrow. The patient then receives the harvested stem cells through an intravenous (I.V.) line in a procedure similar to a blood transfusion. It takes between one to five hours to complete the transplant. 

Bone marrow transplants have varying degrees of success. Several factors – including shared race and ethnicity between the patient and the donor – can increase the odds of a successful transplant, and decrease the odds that the patient’s body will reject the new marrow.

The National Marrow Donor Program (NMDP) estimates that bone marrow or cord blood transplant could help more than 35,000 children and adults with life-threatening diseases every year. Patients who are diagnosed with leukemia, lymphoma and other blood cancers are responsible for approximately 85 percent of transplants facilitated by NMDP. There were more than 2,600 marrow and cord blood transplants in 2005, according to the NMDP.

Advances in transplant procedures have made transplants a viable option for more patients. Research continues to develop transplants that are less dangerous and more effective for a wider range of people and conditions.