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Process of Bone Marrow Transplantation (BMT)

The process of bone marrow transplantation is a lengthy and complicated one. Following is a brief summary of the different steps in performing a successful BMT.

Selection of patients:

This step is one of the most important steps in the process of BMT. This is the prime responsibility of the hematologist or medical oncologist who is in charge of treatment of the cancer. He should be familiar and knowledgeable about the indications as well as the whole process of BMT.

Age limits:

Autologous BMT: 65 (up to 70 years of age in patients who are in excellent general condition.)

Allogeneic BMT: 55 ( up to 65 years of age in patients who suffer from a potentially curable illness.)

Unrelated BMT: 45 years of age is the highest age limit. Toxicity and mortality of unrelated BMT is extremely high in individuals above age of 45.

Underlying Illness:

Many illness can potentially be cured with BMT. Following is a partial list of conditions that should be considered for transplant:

• Acute Myeloid Leukemia

• Acute Lymphoid Leukemia

• Chronic Myeloid Leukemia

• Chronic Lymphoid Leukemia

• Lymphomas

• Breast cancer

• Multiple Myeloma

• Testis cancer in relapse

• Certain non cancerous conditions:

  • Aplastic anemia

  • Thallasemia

  • Congenital immunodeficiency syndrome

Determination of type of Transplant:

This would depend on the underlying condition as well as patient's age and availability of Allogeneic donor. The Allogeneic donor has to be genetically similar to the patient and this is determined by series of blood tests known as HLA typing.

Pre-transplant testing:

If the decision is to go ahead with the transplant, then a series of tests are performed to make certain that the patient can tolerate the procedure. These include evaluation of Heart, Lungs, Kidneys and Liver.

Meeting with the transplant specialist and visiting the transplant Unit:

Patients along with their family members will have a formal visit with the physician and members of the team who will be in charge of the transplant. The Transplant unit is a highly controlled environment with special air filters. Hand washing wearing a gown and using shoe covers are essential parts of entering this area. Patients name is then entered in a waiting list for an available bed.

Admission to the transplant unit:

If all goes well, patients are then admitted to the unit. Patients will have a central line ( Central Venous Access Line) to ensure adequate Intravenous access for usage of drugs and blood products. Patients are given a special diet to reduce the risk of infections as well as frequent oral rinses to maintain good oral hygiene. All patients are seen by an oral care physician to assure prevention of oral infections during transplant.

Removal of bone marrow cells:

This can be done by either removing the cells directly from the bone marrow ( Bone Marrow Harvest ) or from the blood. Bone marrow cells circulate in the blood. They can be removed from the blood by a procedure referred to as Apheresis.

Direct removal of cells from the bone marrow is achieved by multiple punctures and suctioning of the marrow from pelvic bone. This procedure is done in an operating room and under heavy anesthesia, i.e. general or spinal anesthesia. Up to one liter of marrow may be removed to ensure a successful transplant.

Preparation of the cells:

In Autologous BMT, cells are placed in special bags and are frozen in Liquid Nitrogen, until the day of transplant. When time is appropriate, the bags are taken out of the freezers and are thawed and brought to body temperature and made ready for infusion.

In Allogeneic BMT, the harvest procedure is performed on the day when the transplant has to be performed. Marrow is processed and brought to the patient's bedside and is infused intravenously as soon as possible.

Conditioning Regimens:

This refers to the treatment regimen used to eradicate the cancer cells. This treatment is offered prior to actual transfusion of marrow cells. Most regimens use a combination of chemotherapy with or without radiation. If radiation is part of the regimen, it is given following the chemotherapy. The length of this step depends on the drug combination and varies from 5-10 days.

Transplantation of Marrow:

Following completion of the conditioning treatment, the marrow is given to the patients in form of an intravenous transfusion of the cells. Marrow cells once in the blood, will find their way to the patient's bone marrow where they will start growing and producing normal cells.

Common complication:

These regimens are very toxic on bone marrow cells and cause severe lowering of white blood cells, platelets and red cells. Most patients will require Intravenous antibiotics, blood and platelet transfusion as well as Intravenous nutrition. Any other complication should be dealt with in an urgent basis. Length of stay in the hospital depends on the type of transplant and degree of complications.