Non-Hodgkin's Lymphoma - Transplantation

Transplantation

Stem cell procedures have proven to produce long-term survival and even cures in some patients with intermediate- and high-grade non-Hodgkin's lymphomas.

Stem cell transplantation involves removing and replacing stem cells, which are produced in the bone marrow. Stem cells are the early forms for all blood cells in the body (including red, white, and immune cells). Cancer treatments harm growing cells as well as cancer cells, and so the healthy stem cells must be replaced by transplanting them from the donor into the patient.

Transplantation is usually reserved for patients with relapsed aggressive lymphoma who are still sensitive to the effects of chemotherapy. Transplantation procedures do not work for patients whose tumors are not responsive to drugs.

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Collecting the Stem Cells

Sources of Cells. Stem cells must first be collected in one of the following ways:

• Directly from blood, called peripheral blood stem cell transplantation
• From bone marrow, called bone marrow transplantation
• From umbilical cords or placentas -- this procedure uses donor cells, but has a lower risk for immune system rejection of the cells than with a standard donor transplant. It takes longer to restore blood cells with this process, so it is generally used for children and sometimes adults with low weight.

Peripheral blood stem cell transplantation is easier to perform and is done more often than bone marrow transplantation. It also seems to be superior in terms of cost, quality of life, and the need for less supportive care.

Donor or Patient Cells. The marrow or blood stem cells can be taken from the patient (autologous) or from a matched donor (allogeneic):

• In an autologous transplant, the marrow or blood cells used for replacement are taken from the patient. There is some danger, however, that these cells may contain tumor cells, and that the cancer can regrow. It is unclear if this approach improves survival compared to standard chemotherapy for newly diagnosed disease. However, it clearly has benefits in the treatment of some forms of relapsed non-Hodgkin's lymphomas. There is also a higher risk for leukemia. (This risk is lower in peripheral stem cells transplants than in bone marrow transplants.)
• In an allogeneic transplant, bone marrow or stem cells are taken from a donor. Siblings are the best donors. Relapse rates can be very low with this approach, and cure may be possible in some cases. However, it is highly toxic and donor and recipient must be matched as closely as possible to avoid rejection by the immune system, a serious complication called graft-versus-host disease. Advances in techniques are reducing the toxicities associated with this approach. Older patients who cannot tolerate the preparatory treatment required for a standard allogeneic transplant may be able to receive a non-myeloblative transplant (“mini-transplant), which uses lower doses of chemotherapy and radiation.