Stem cell transplants are often one of the last choices a patient has to survive cancer. All have already gone through chemotherapy, radiation therapy or both and this is the next step in their treatment. Patients have two choices in transplants autologous or allogeneic. In an autologous transplant stem cells are collected from the patient and then given back to them at a later date after the body has been properly prepared for transplantation. In an allogeneic transplant stem cells are collected from a donor, related or unrelated to the patient, then transplanted into the patient.
Stem cells can be collected in two different ways. One way is via bone marrow and the other is via peripheral blood. The donor’s or patient’s bone marrow is collected from the pelvis, femur or sternum, though the pelvis is the most common, and then infused into the patient via a central line. In a peripheral blood stem cell collection the donor or the patient has their stem cells collected via a central line in a process called apheresis. This can take multiple collections to ensure enough stem cells for transplantation.
Both procedures need to be meticulously planned and all support medications given to ensure successful collection. There are many cancers that stem cell transplants are commonly used for. Multiple myeloma, acute lymphoblastic leukemia, Hodgkin’s disease and chronic myelogenous leukemia are more commonly treated with transplantation. Each of these cancers has a different success rate, some have a higher success rates than with chemotherapy alone. Proper preparation is important for stem cell transplants. All patients undergo chemotherapy prior to transplantation.
This is used to clear out the bone marrow of cells to ensure a successful transplant. Also most patients have already undergone chemotherapy in hopes of curing their cancer without having to have a stem cell transplant. Chemotherapy is not the only medication used to aid in transplants. Patients generally receive G-CSF injections to help promote cell production prior to harvest and to aid in engraftment. Transplantation is not without risks, patients can experience fatigue, infections, lowered red blood cells and platelets or even graft versus host disease.
These can all be treated though with good supportive care by the physicians and other support staff. Research shows that stem cell transplants should be done in certain cases because it can allow a greater quality of life by ridding the body of cancer and promoting healthy cell growth and allowing a patient to have other options of therapies to overcome cancer. Multiple myeloma is one of the cancers that can have successful outcomes by a stem cell transplant. Though research shows this is not a true curative treatment for patients, it can give them a chance at a longer life.
Both autologous and allogeneic transplants can be done for multiple myeloma though allogeneic transplants are more successful. Bruno et al, (2007) attributes this to the inability of the pre-transplant chemotherapy to eradicate all myeloma cells. Also allografting using stem cells from a HLA-identical sibling has higher success rates than transplants using non HLA-identical siblings. Another cancer that has successful outcomes after transplantation is acute lymphoblastic leukemia. Kiehl et al, (2004) shows that up to 46% of patients who receive an allogeneic transplant have successful disease free survival.
Higher risk patients and patients who are in their second complete remission should undergo a stem cell transplant for a greater chance at long term survival. Those who are in their third complete remission, or have had induction failure, have a lower chance at a successful transplant with disease free survival. As stated by Kiehl et al, (2004) these patients only have a 5-15% chance of long term survival despite transplantation. The allogeneic donor can either be related or unrelated, though the donor of choice is a matched sibling. This is not always possible so transplantation should go ahead with and unrelated donor.
Hodgkin’s disease can be successfully cured with chemotherapy and radiotherapy, though some patients will need transplantation at some point. Research by Sureda et al, (2001) shows that these patients can achieve long term survival after an autologous stem cell transplant. These patients have generally relapsed after initial chemotherapy or have refractory disease. Poorer outcomes after transplantation can be found in patients who have a short remission period or bulky disease at time of transplantation. This is not a deciding factor in not attempting a transplant though.
Stem cell transplants continue to be the only curative option for chronic myelogenous leukemia. Most of these patients receive an allogeneic transplant though some undergo and autologous if no donors are available. Maziaz and Mauro, (2004) show that an allogeneic transplant from a sibling donor had a 60% disease free survival at 5 years. Autologous transplants have an 80% survival rate at 5 years though these patients are only in remission not truly disease free. Age, other health factors, and donor availability are factors to be considered prior to transplant.
Maziarz and Mauro, (2003) bring up the question of non-transplant therapy by using Imatinib. This medication is still being researched regarding its efficacy and curative rates. This could be an option for patients who are too ill to undergo a transplant. Stem cell transplants are reliant on multiple medications prior to and after transplantation. Chemotherapies are used to ablate the bone marrow and ready it for production of new healthy cells. Granulocyte colony stimulating factor, G-CSF, is used pre and post transplantation.
This medication assists in cell production for a successful harvest and then for successful engraftment. High dose chemotherapies such as Ifosfamide, Carboplatin and Etoposide are often used prior to transplantation. (Schlemmer et al, 2006, Straka et al, 20003) These medications ready the bone marrow for transplantation by destroying cells, both good and bad. Elderly patients and patients who cannot tolerate full dose therapy are often given doses at a decreased rate. This does not decrease the chances of a successful transplantation. (Straka et al, 2003) Without obliteration of all cells successful engraftment could not happen.
The stem cells would be overrun by cancerous cells and the disease would continue. This is one reason why so much chemotherapy is given prior to transplantation. Granulocyte colony stimulating factor, G-CSF, is a very important part of stem cell transplantation. It stimulates the bone marrow to produce more leukocytes. G-CSF is used both pre and post transplantation. When used pre transplantation it helps produce more lymphocytes that are then harvested for transplantation. Post transplantation it is used to support engraftment and decrease neutropenia.
Samaras et al, (2010) states the use of G-CSF can reduce the time to engraftment and potentially lower the risk for post-transplant infections. There are different side effects and complications that can arise from transplantation. As the body is prepared for transplantation, the body is stripped of its natural defenses against infection. With no white cells to help battle against opportunistic infections a patient can become extremely ill. They are also at risk for anemia and thrombocytopenia as the chemotherapy also destroys red blood cells and platelets.
This is one reason patients are kept in the hospital for many days during high doses of chemotherapy. They are also at continued risk after transplantation until engraftment and cell recovery happens. Another major side effect that can happen is graft versus host disease (GVHD). This is where the donor cells perceive the recipient’s body as foreign and begin to attack the body. There are 4 grades of graft versus host disease and they can either be acute or chronic. Acute GVHD generally happens as the new cells are engrafting into the host body.
Chronic GVHD can happen years later and is more severe in effects to the body. In the acute phases of GVHD the patient can be treated and cured by the use of short term immunosuppressant therapy and steroids. Long term immunosuppression can lessen the effects on the body in chronic GVHD. This in itself can lead to infections due to chronic immunosuppression. (Kiehl et al, 2004, Bruno et al, 2007) Most patients experience some level of fatigue while recovering from transplants. This can be exacerbated by nausea, vomiting, poor appetite, sleep issues and other side effects of transplantation.
As patients experience more fatigue they become less inclined to do further activities. It is important to treat all symptoms effectively and encourage patients to be up and moving. This can shorten hospital stays and lessen the chances of infections. (Hacker et al, 2006) Stem cell transplants though complicated and risky are still one of the best choices for many patients. They can be the last chance at survival for patients as well as the best option for the possibility of longer life living with cancer. Relapse and failure of transplant are risks that patients choose to take.
There is a complex series of chemotherapy and supportive medications for transplant, but without these, transplantation would not be possible at all. Though side effects can happen, the benefits far outweigh the risks associated with transplantation. Research shows that stem cell transplants should be done in certain cases because it can allow a greater quality of life by ridding the body of cancer and promoting healthy cell growth and allowing a patient to have other options of therapies to overcome cancer. As the years continue and further research is done stem cell transplants will become the first step in caring for cancer patients.
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