Chromosomal Abnormalities and BMT
Dear OncoLink "Ask The Experts,"
My friend has just undergone the induction phase of chemotherapy for AML (acute myelogenous leukemia), and has been advised she should get a bone marrow transplant soon, rather than going through a consolidation phase of chemotherapy. Her cytogenetics include a translocation of chromosomes 19 and 11. We presume that this abnormality is what is leading to the need for more aggressive treatment. Could you explain what a translocation is, why it requires more aggressive treatment, and if there is anything else involved in the BMT treatment to address the translocation?
Selina M. Luger, MD, Director of the Leukemia Program and Assistant Professor of Medicine at the University of Pennsylvania, responds:
After initial induction chemotherapy for AML , it has been shown that there is a benefit to additional therapy. Whether that therapy should be consolidation chemotherapy or a bone marrow or stem cell transplant is discussed with each patient, with the consideration of several factors.
In making decisions about the appropriate therapy for a patient with AML, we take several issues into consideration, including age of the patient, the way the patient has tolerated the initial chemotherapy, as well as the likelihood that the leukemia will relapse.
One of the best predictors of likelihood of relapse is the chromosomal abnormalities that are seen at the original diagnosis. Many patients with AML have abnormal chromosomes in their leukemia cells. We know that these predict for the likelihood of relapse. Normally people have 23 pairs of chromosomes in each cell (numbered 1 through 22, and then X and/or Y chromosomes, for female or male gender). Some of the abnormalities we see are: deletions, if there are missing chromosomes; trisomies, if there is a 3rd copy of a chromosome instead of 2 copies; or translocations, if a piece of one chromosome hops onto another chromosome. Studies that have been done over the years have demonstrated a predictive value to knowing the chromosomal findings at diagnosis. So, given that we know that a person with one of these abnormalities is more likely to relapse, it may be suggested that the person pursue more aggressive therapy.