To appreciate why the expertise of an institution like the University of Michigan Comprehensive Cancer Center is so critical to success in BMT, it's important to understand what's involved in the treatment.
Inside this section
What illnesses are treated with blood or marrow transplantation?
Blood and marrow transplants are used to treat cancers such as:
- bone and soft-tissue sarcomas
- brain tumors
- other conditions including the failure of a patient's own bone marrow or certain immunodeficiency disorders
Blood or marrow transplantation has been shown to effectively slow or stop the growth of some cancers. However, since the procedure greatly compromises the body's immune system, it can bring about one or more severe complications. Because of the significant risks involved, BMT is used for patients whose conditions are life-threatening or have not responded to other treatments.
Transplantation is a treatment alternative for both adults and children. Learn more about pediatric blood and marrow transplantation.
What is bone marrow?
Bone marrow is the spongy tissue found inside the body's large bones. It is responsible for making blood cells including red blood cells, white blood cells and platelets. It is also home to the immune system.
What are stem cells?
Blood cells develop and grow in the same way as other human cells, beginning with a parent cell known as a stem cell. During this process, which takes place in the bone marrow, stem cells divide and mature, forming all the different types of blood cells: white blood cells, platelets and red blood cells.
Stem cells are usually found inside the bone marrow spaces of large bones; however, they can travel from one bone to another through the blood stream. The blood that circulates through the body, called peripheral blood, is another source of stem cells. When we talk about stem cell transplant, we use adult stem cells; this is not the same as embryonic stem cells.
What is a bone marrow transplant?
A blood or bone marrow transplant is a transfusion of bone marrow stem cells or blood stem cells which have been previously collected from the patient or a donor. It is performed as part of a treatment protocol intended to wipe out cancer cells in the body. This is a far more aggressive approach than is used in typical cancer treatment.
In standard cancer therapy, chemotherapy is administered in as small a dose as possible because it is so damaging to the body's immune system. In blood or bone marrow transplantation (BMT), much higher doses of chemotherapy are used, sometimes accompanied by radiation. This process, called conditioning, temporarily shuts down the body's immune system and its ability to generate new blood cells. After conditioning destroys the patient's existing bone marrow, the transplant replaces it with "new" bone marrow.
What are the different types of blood and marrow transplantation
The type of transplant a patient receives depends on who donates the bone marrow or blood stem cells. The most common types are:
the patient donates his or her own stem cells prior to receiving chemotherapy, and those cells are preserved for transplantation after treatment.
stem cells are donated from a genetically-matched family member (usually a brother or sister). Genetic matching, called HLA matching, is done from blood samples. When the donor is an identical twin, the procedure is referred to as a Syngeneic Transplant.
Matched Unrelated Transplant
stem cells are donated by someone other than a family member. A donor is found through a worldwide donor registry coordinated by the National Marrow Donor Program (NMDP). The University of Michigan is a member center of the NMDP. Matched unrelated transplants are also categorized as allogeneic transplants.
What determines whether a patient receives an autologous transplant or an allogeneic transplant?
The type of transplant recommended depends on the unique needs of the patient. Each transplant type brings with it specific benefits and risks. Autologous transplants have a lower risk of infection during the conditioning period because a patient's immune system will recover more quickly. Also, since the patient acts as his or her own donor, the risk of developing complications from rejection of the transplant, such as graft-vs.-host disease, are very rare. For those and other reasons, autologous transplants are the preferred method of transplantation for many patients, including those with lymphoma.
Other forms of cancer, including acute myeloid leukemia (AMD), present a higher risk of relapse or recurrence. For those patients, the increased risks of infection or rejection presented in allogeneic transplants may be worth accepting in an attempt to knock out the cancer.
How are bone marrow stem cells or blood stem cells collected?
Bone marrow stem cells are collected from the bone marrow of either the patient or a donor through a process called harvesting. The procedure is performed in the operating room under general or spinal anesthesia. Several needles are placed through the skin into each hip bone (pelvis) to extract the marrow. Once collected, the marrow is filtered and placed into blood bags.
The entire harvesting procedure takes one to two hours. The patient or donor may receive a blood transfusion during the collection to replace the blood removed with the bone marrow. Once completed, a large bandage is placed across the hips, which remains in place for 24 hours. Discharge from the hospital is generally the same day. Soreness is common after harvesting, and pain medication is given as needed. Normal activity can usually be resumed within 3-4 days of harvesting, and recovery from the procedure is usually complete within about 2 weeks.
Stem cells can also be harvested from the blood circulating through the body, called peripheral blood, through a collection method called peripheral stem cell apheresis. Apheresis involves inserting a needle into one arm and connecting attached tubing to a machine that separates and collects the peripheral stem cells. The remaining blood components (white cells, red cells and platelets) are returned to the body through a needle in the other arm. In some cases, an IV is inserted in the neck or groin if the veins in the arms are not strong enough for the procedure.
For several days prior to the procedure, the patient or donor receives injections of a drug called growth factor to produce a greater number of stem cells to be released into the blood.
Apheresis is performed on an outpatient basis with little or no discomfort. Most patients or their donors will have 1-3 procedures done to collect the required number of stem cells, with each procedure taking 2-3 hours.
What is involved in the actual transplant?
The transplant or infusion is similar to a blood transfusion. The "transplant" is given through an IV placed in the patient's arm.
What happens after blood or marrow transplantation?
Approximately 2-4 weeks after a transplant, doctors look for signs that the donated bone marrow is "engrafting" or beginning to grow. The first sign of this is the production of white blood cells. Platelets often take longer to begin developing.
Once engrafting is confirmed and the patient's condition is stable, the patient can be discharged from the hospital. Although each patient's situation is unique, the following general criteria are used to determine when a patient can be discharged from the hospital:
- No evidence of an emerging infection or complication such as graft-vs.-host disease (GVHD).
- The patient is able to tolerate food, fluids and oral medications.
- The patient's physical ability has rebounded enough to function outside the hospital.
- Patient and caregiver have completed post-transplant education.
Still have questions?
The nurses at Cancer AnswerLine™ have answers. Call 1-800-865-1125 and you'll get a personal response from one of our registered nurses, who have years of experience in caring for people with cancer.