Bone marrow transplantation is clearly a treatment approach that is only applicable to a subset of CLL patients. Until recently, CLL patients were generally not considered candidates for bone marrow transplantation because of their age at presentation and the indolent nature of CLL. However, increasing consideration is being given to CLL patients with high-risk disease and poor prognostic factors such as, lymphocyte doubling time of less than 12 months, diffuse pattern of bone marrow infiltration, and adverse cytogenetics.

There are two main types of transplants. Autologous transplantation uses the patient's own bone marrow or stem cells. After the cells are removed from the patient, they are treated to remove leukemic cells--a process called purging--and are then given back to the patient. Allogeneic transplantation uses bone marrow or stem cells collected from a matched donor who may be related or unrelated to the patient.

The advantage of an autologous transplant is that there is no risk of graft-versus-host disease. The disadvantage centers on the possibility that leukemic cells may be given back to the patient. The advantage of allogeneic transplant is that the cells given to the patient are totally free of leukemia. The disadvantage is that the donated cells may attack the patient's body, which is called graft-versus-host disease. A matched unrelated donor transplant carries the greatest risk of all the transplant procedures with a three in ten chance that the patient will die from the procedure itself.

Transplant is usually considered only for patients with progressive disease who are running out of other treatment options and therefore have a poor prognosis. When the risk of CLL becomes greater than that of transplantation, the transplant option comes into consideration.

Age is also a factor when considering transplant. Younger patients tend to want, and are often able to better withstand, aggressive treatment. In some cases, aggressive treatment also seems to be more effective in younger patients. Older patients frequently don't want aggressive therapy, because they don't want to go through all of the potential side effects. The ability to rebound from high dosage chemotherapy also diminishes with age, and the risk of graft-versus-host disease is well established to increase with advancing years. As a rule of thumb, allogeneic transplantation becomes less of an option after a patient reaches 60 years of age, and autologous transplantation is usually ruled out after 65 years of age. However, it is important to note that there are some 65 year olds who are otherwise very fit and healthy and could be candidates for transplant, while there are some 45 year olds who would not survive the procedure. The overall fitness of the patient is therefore somewhat of an overriding factor in determining the age-limit for transplant.

Transplant should not be considered or undertaken too early in the disease when the patient may have many more quality years of life with, or without, treatment. Similarly, it is important not to wait until the patient has already failed all other forms of treatment. In the latter situation, it is very difficult to perform a bone marrow transplant and achieve a good result. In summary, there is a window of time during the course of CLL when transplant makes the most sense to consider.

Patients who are considering transplant are encouraged to seek institutions and physicians that are performing this procedure in conjunction with CLL research. If this is not possible, patients are urged to find facilities that are experienced in transplants and have the skilled staff and state-of-the-art support services required to undertake this procedure.