Acute myloid leukemia (AML) defines a spectrum of myeloid malignancies with many common features but also considerable variability in biology and clinical outcomes. AML is a clonal disorder with all leukemia cells in an individual patient descending from a common primitive leukemia stem cell. The leukemia cells (blasts) grow quickly in the bone marrow and crowd out the normal red blood cells, white blood cells and platelets.
AML can affect people of any age, but is most common in adults. In the large majority of cases, no clear etiology can be found, although a number of risk factors are known such as exposure to ionizing radiation, benzene, and several genetic syndromes.
Some patients with AML will achieve long-term remission with chemotherapy alone, whereas for others the disease is more aggressive and chemotherapy alone may not be enough. Most transplants for AML are allogeneic. Allogeneic donors may be HLA matched sibling, unrelated donor or umbilical cord blood unit. Autologous transplants are not usually done for AML because the risk of relapse is higher than with allogeneic transplant.
Whether a transplant is right for an individual patient depends on how likely the disease is to return (relapse). This is based on specific features of the leukemia called risk factors. A transplant physician will weigh the risk of the leukemia relapsing against the risk of getting a transplant. One of the risk factors is determined through cytogenetic testing of the bone marrow. Specific changes in the chromosomes predict which patient will have a lower risk of relapse and which patient will have a higher risk of relapse. If your disease has a high risk of relapse and you have a suitable donor, then delaying the transplant may lower you likelihood of long-term remission and cure.
There are medical guidelines for when an individual should be referred for transplant consultation. It is recommended to talk to a transplant physician if:
- you had myelodysplastic syndrome before you developed AML.
- your initial chemotherapy did not result in remission.
- your initial chemotherapy resulted in remission, but cytogenetic or melucular testing shows high-risk disease.
- you have repalsed one more more times after chemotherapy.
- initial therapy leads to remission, but cytogenetic or molecular testing shows high-risk AML.
- initial chemotherapy does not result in remission.
- child relapses one or more times.