Bone marrow is a spongy tissue found inside bones. The bone marrow in the breast bone, skull, hips, ribs and spine contains stem cells that produce the body's blood cells. These blood cells include white blood cells (leukocytes), which fight infection; red blood cells (erythrocytes), which carry oxygen to and remove waste products from organs and tissues; and platelets, which enable the blood to clot.
In patients with leukemia, aplastic anemia, and some immune deficiency diseases, the stem cells in the bone marrow malfunction, producing an excessive number of defective or immature blood cells (in the case of leukemia) or low blood cell counts (in the case of aplastic anemia). The immature or defective blood cells interfere with the production of normal blood cells, accumulate in the bloodstream and may invade other tissues.
Large doses of chemotherapy and/or radiation are required to destroy the abnormal stem cells and abnormal blood cells. These therapies, however, not only kill the abnormal cells but can destroy normal cells found in the bone marrow as well. Similarly, aggressive chemotherapy used to treat some lymphomas and other cancers can destroy healthy bone marrow. A bone marrow transplant enables physicians to treat these diseases with aggressive chemotherapy and/or radiation by allowing replacement of the diseased or damaged bone marrow after the chemotherapy/radiation treatment.
While bone marrow transplants do not provide 100 percent assurance that the disease will not recur, a transplant can increase the likelihood of a cure or at least prolong the period of disease-free survival for many patients.
Bone marrow transplantation (BMT) is a relatively new medical procedure being used to treat diseases once thought incurable. Since its first successful use in 1968, BMTs have been used to treat patients diagnosed with leukemia, aplastic anemia, lymphomas such as Hodgkin's disease, multiple myeloma, immune deficiency disorders and some solid tumors such as breast and ovarian cancer.