Genomic studies and advances in technology have increased researchers’ knowledge of several genetic syndromes that put people at risk for acute myeloid leukemia (AML).
An article that appeared in Hematology Advisor recently stated that more people predisposed to AML are now being identified due to increased awareness, genetic counseling, and a wide range of testing options.
Questions Surrounding Stem Cell Transplants
Controversy has emerged as to whether or not patients should be offered stem cell transplantation (SCT) in accordance with their risk category.
Will SCT offer the same benefit to a patient who is “at increased genetic risk” for AML as it would for a patient with an active disease?
It is almost a given that a patient with a ninety percent risk of developing AML would have more to gain by SCT than a patient with a twenty percent risk.
Then there are other factors to consider such as the patient’s health and age. Another consideration is the availability of a suitable donor if the patient is being considered for Autologous SCT.
Hematopoietic stem cells
By the way, bone marrow transplants are now referred to as hematopoietic stem cell transplantation (HSCT). Hematopoietic stem cells are found in the bone marrow. They can create any cell required by the body. They are responsible for the daily restoration of our blood supply. Hematopoietic cell transplantation, or HCT, is a procedure that creates marrow and immune function. The cells are infused into patients who have inherited or acquired nonmalignant or malignant disorders. Although HCT is effective against myeloid neoplasms (disease of the blood cells and bone marrow) it is not effective on solid tumors.
Allogeneic and Autologous SCT
Allogeneic SCT begins with a conditioning regimen of chemotherapy (and possibly radiation) to destroy any remaining cancer cells. The stem cells are “collected” from a donor (preferably a sibling or close relative) and transferred to the patient. This procedure involves a risk called graft vs. host disease (GVHD). In GVHD the patient’s immune system attacks the transplanted cells. In order to minimize this risk, the patient receives high-intensity chemotherapy.
Autologous SCT involves the patient’s own stem cells. These cells are filtered out of the patient’s blood supply, preserved and stored. The patient will undergo additional chemotherapy to ensure that all cancer cells are destroyed. The preserved cells are infused back into the body.
The advantage of autologous SCT is that the body recognizes the cells and does not attack or reject them. However, an autologous stem cell transplant carries its own risk. It is possible for some of the patient’s diseased cells to reenter the body during the transplant procedure.
Patients who have been treated with the standard AML therapy may not be eligible for SCT. They are at risk of experiencing severe adverse events. In such cases, early intervention is necessary, but it is difficult for the doctors to pinpoint the optimum time.
The last factors to consider are the consequences of not undergoing SCT. This analysis is problematic due to the lack of data and the fact that the genetic syndromes are extremely rare. Many of these syndromes have been newly identified. Currently, there is very little clinical data that supports results either with transplants or without.
Perhaps one of the most important considerations for performing SCT is, in spite of its potential for preventing the onset of leukemia, what is truly in the best interest of the patient?
Researchers offer a hypothetical scenario in which ninety percent of a cohort is likely to develop leukemia. If these patients are treated with an SCT then it would eliminate the risk of secondary AML in that ninety percent.
Will SCT Provide a Benefit for All or Just Some Patients?
This question may come under the heading of ethical consideration. Should clinicians offer or encourage the transplantation to all patients who have a syndrome that puts them in the risk category of possibly developing AML?
The emphasis should be on cancer care that is value-based. Does SCT provide value for the patient? Is it in conflict with the personal values of the patient?
It Takes a Village
The report suggests that physicians not weigh the risks and benefits without involving the patients and their family. Patients will refer back to their own personal experiences when they are being considered for SCT. Therefore the psychosocial aspect must be considered as well as the medical implications.
The SCT team (multidisciplinary) might include transplant doctors, oncologists, social workers, geneticists, and psychologists.
A Mismatch in the Global Stem Cell Registries
Eighty percent of Caucasian patients will be able to match with a fully-matched donor from any of the donor registries. However, the possibility of finding a genetic match for people of color drops dramatically to fifty percent or less. This is due to the fact that these populations are heavily underrepresented in the bone marrow registries.
This is especially critical because SCT must be performed within the first two to three months after diagnosis of the disease in order to avoid infection.
The medical community is actively pursuing this shortfall with several transplant options.
The first option being tested is an umbilical cord blood transplantation. The advantage of this procedure is that unlike the marrow donor it is not necessary for the cord blood to be a close match. Therefore it is a possible option to be used when a patient has an uncommon tissue type. The second option being tested is a mismatched family relative.
Contact BE THE MATCH REGISTRY® to learn more about how someone you know can donate their baby’s umbilical cord blood to a public cord blood bank. More than 25,000 patients worldwide have received cord blood transplants. There are over 295,000 cord blood units in public cord listed on the Be The Match Registry®