Stem Cell Transplants
A stem cell transplant, in combination with high-dose chemotherapy, is a treatment option that offers a chance for durable remission for people with multiple myeloma. Because the chemotherapy attacks all the blood cells in the bone marrow—not just the multiple myeloma cells—a stem cell transplant provides the body with a new source of healthy cells.
Bone marrow transplants are no longer done in multiple myeloma. Instead, almost all transplants in multiple myeloma are now obtained from the blood and are referred to as peripheral blood stem cell (PBSC) transplants.
There are generally two types of stem cell transplant performed for multiple myeloma: autologous stem cell transplant, which uses the patient’s own stem cells, and allogeneic stem cell transplant, which uses stem cells from a donor.
Autologous stem cell transplant
In an autologous stem cell transplant, the stem cells are taken from the patient’s own blood. Most patients with multiple myeloma who are eligible for transplant undergo this type of transplant, as there are typically fewer complications with an autologous transplant than with a transplant that uses donor stem cells.
All patients who are eligible for transplantation are encouraged to have stem cells collected (also known as “harvested”) so the cells are available if they choose to undergo transplantation at some point during the course of the disease.
The cells are stored until they are needed for the transplant. Then the patient receives treatment such as high-dose chemotherapy, sometimes with radiation, to kill the cancerous multiple myeloma cells. Following the chemotherapy or radiation therapy, the stored stem cells are infused back into the patient’s blood.
The transplant procedure may be inpatient or outpatient, depending on the center and/or patient preference.
Allogeneic stem cell transplant
Allogeneic transplant involves transferring stem cells from a matched donor (usually a relative) to a multiple myeloma patient following high-dose chemotherapy or radiation therapy.
In very rare cases, allogeneic transplant can be curative due to the graft-versus-tumor effect, in which the healthy donor cells help destroy the remaining multiple myeloma cells in the patient’s body. However, allogeneic transplant is rarely used in multiple myeloma because the likelihood of risks outweighs the potential benefits. Specifically, there is a high risk for graft-versus-host disease (GVHD) with allogeneic transplant. This potentially serious complication occurs when the donor immune cells see the patient’s tissues as foreign and attack them.
For people who have multiple myeloma and happen to have an identical twin, a special type of allogeneic transplant, called a syngeneic transplant, can be performed. This type of transplant uses the identical twin as the donor, reducing the risk for GVHD and offering the optimal transplant for patients with multiple myeloma.
Radiation therapy, which uses high-energy particles or rays to damage cancer cells and prevent them from growing, is proven to effectively treat multiple myeloma in specific situations and/or reduce complications from bone disease. Radiation therapy may also be called radiotherapy, X-ray therapy, or irradiation.
Radiation therapy is administered using a machine that directs high-energy rays at the patient’s body. The rays may be directed at a particular area of bone (called “local radiation”) or at a larger part of the body. When a patient receives radiation therapy of the entire body, it is called total body irradiation (TBI). TBI and radiation therapy directed at large parts of the body are rarely used in the treatment of multiple myeloma.
In high doses, local radiation therapy (sometimes given with chemotherapy) is used to treat solitary tumors in bone or soft tissue (plasmacytomas). In low doses, local radiation therapy is sometimes used to relieve uncontrolled pain or to help prevent or treat bone fractures or spinal-cord compression.
Along with cancer cells, some normal cells may be affected by radiation; fast-dividing cells, such as those in the bone marrow and the lining of the digestive tract, are most susceptible to damage by radiation therapy. However, most normal cells appear to recover fully from the effects of treatment.
Radiation therapy often makes patients feel tired and lose their appetite, and it can make the skin above the treated area more sensitive and irritated. Other side effects depend on the part of the body that was treated. For example, radiation to the pelvic area may cause suppression of the bone marrow and lead to reduced blood cell counts. This is because half of the body’s bone marrow is found in the pelvic bones. Radiation to the pelvic area can also affect the lower digestive tract, causing symptoms such as diarrhea, spasms and, in rare cases, bleeding. It can also affect the reproductive organs.