Stem Cell Therapy
Stem cells are young blood cells found in bone marrow that enter the blood stream once they are mature. Bone marrow is often damaged during chemotherapy and radiation or by the disease itself. Damaged cells often do not reproduce as quickly as healthy cells or diseased cells, so stem cell transplants are often needed to replace the damaged bone marrow and stimulate new cell growth. In certain types of cancer, stem cell therapy allows the physician to prescribe higher doses of chemo and radiation to better treat the disease. Stem cells can not only replace damaged cells, but they can also fight cancer cells better than the patient’s own immune cells.
Stem cell therapy can be categorized as autologous, allogeneic, or syngeneic.
- Autologous stem cell transplants – your stem cells are collected and frozen before you start cancer treatment, so they can be replaced in your body following your treatment. This type of transplant is often used in multiple myeloma, lymphoma, and leukemia. An autologous stem cell transplant will help reduce the risk of infection and graft failure, because they are your body’s own cells. A disadvantage of an autologous transplant is that your cells may have built immunity to the cancer, so they do not have the ability to fight the cancer when placed back in your body, or they may have cancer cells in them which could cause the disease to spread. Your physician will discuss the risks and benefits associated with an autologous transplant and help you decide your best treatment option.
- Allogeneic stem cell transplant –donor cells are used to replace the damaged cells. A close family member is often the best source, but if none are available, then a stem cell match can often be found using a national registry such as Be the Match. Donor cells will have to build a new immunity to the cancer cells that are left in the body, which is an advantage over an autologous transplant which uses the patient’s own already immune cells. An additional advantage is multiple harvests can be taken and used for a transplant, whereas in autologous, the patient is often too sick for multiple collections. A possible risk of allogeneic transplant is that the donor cells could not only attack the cancer cells, but they could also attack the patient’s normal healthy cells. This is called graft vs. host disease. Your oncologist will discuss the potential risks and benefits of this type of transplant.
- Syngeneic stem cell transplant – donor cells are from an identical twin or triplet. Because the donor cells are the same tissue type, a syngeneic transplant will reduce the risk of the donor cells attacking the patient’s own healthy cells. It will also reduce the risk of putting cancer cells back in the body, as with an autologous transplant. However, because the donor is such a close genetic match, the risk of the donor cells building quick immunity to the cancer is increased. As with the other types of stem cell transplants, your physician will discuss the benefits and risks associated with syngeneic stem cell transplants.