The mainstay of treating patients with leukemia, lymphoma, and myeloma is chemotherapy, usually using 2 or more anti-cancer drugs. There are approximately 50 drugs now in use for treating these cancers. Some patients with ALL, Hodgkin lymphoma, and some non-Hodgkin lymphomas can be treated with radiation therapy in addition to chemotherapy.
First introduced approximately 35 years ago, blood and bone marrowstem cell transplantation is now standard treatment for select patients with leukemia, lymphoma, and myeloma. These stem cells may come from an identical twin ("syngeneic") or a donor with the same tissue type ("allogeneic"), such as a sibling. The National Marrow Donor Program keeps a registry of potential unrelated donors.
Other sources of stem cells include those harvested from the patient themselves while the patient is in remission. The harvested cells are treated with chemotherapy and can be frozen to be later infused back into the patient. Stem cells can also be harvested from blood, umbilical cord blood, and placental blood.
The basic concept is that the donor stem cells take hold, attack, and suppress the cancerous cells. The donor cells then take over and produce healthy, non-cancerous blood cells. In order to do this, the patient's bone marrow and immune system has to be wiped out by chemotherapy drugs, a difficult and often toxic process known as "ablative". Now, "non-ablative" techniques use lower doses of immunosuppressive drugs, preserving some of the patient's blood cell and immune system, and making the process much less toxic and more tolerable.