Understanding the purpose behind in-depth AML testing can help patients and care partners feel more informed and empowered. Hematologist-oncologist Dr. Anand Patel explains the key blood, bone marrow, molecular, and genetic tests used to diagnose AML, and to guide care and treatment decisions.
Dr. Anand A. Patel is the Medical Director of the Inpatient Leukemia Service at the University of Chicago Medical Center. Learn more about Dr. Patel.
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Transcript
Katherine Banwell:
Would you explain why testing is so critical in AML?
Dr. Anand Patel:
So, many cancers, including AML, have specific mutations that develop over the course of time that serve as the driver of this. These mutations can have prognostic impact. So, give us a sense of how likely standard therapies are able to work, whether something like a stem cell transplant may be needed to try and cure this, and they can offer therapeutic information.
So, we have several drugs that fall in a bucket of what we call targeted therapies. So, they are very precisely developed for patients that have a specific mutation. In tandem with molecular testing, getting what we call cytogenetic testing. So, looking at the makeup of the chromosomes in these leukemia cells. So, chromosomes being the packets of genetic information. Missing chromosomes, chromosomes rearranged in specific ways, those also help to refine both our prognostic discussion, so, getting a sense of how likely the leukemia is to respond to therapies, and therapeutic decision-making.
Katherine Banwell:
Would you go over the key tests that patients can expect with diagnosis? And you did mention a couple, but maybe we could start with blood tests?
Dr. Anand Patel:
Absolutely. So, for most patients who ultimately are diagnosed with AML, their journey begins with blood work, and typically, what’s called a complete blood count with differential.
So, a complete blood count looks at the different components, most specifically the white blood cell count, the hemoglobin, or red blood cell count, and the platelet count. And then, a differential is someone looking at the white blood cells under a microscope and defining what different types of white blood cells are there. For many patients, what may be found is their white blood cell count is much higher than expected, or much lower than expected, they may have a low platelet count or hemoglobin count, and as that differential is run, there may be abnormal cells or blast cells that are seen in the blood.
Oftentimes, the next step, then, is to perform what’s called a bone marrow biopsy, which is an outpatient procedure. It is typically a bedside procedure, and the entire procedure itself takes maybe about 15 to 20 minutes, with some laying flat afterwards. On that bone marrow biopsy specimen, typically, what’s sent for is what we call a hematopathology review.
So, a pathologist who has expertise in reviewing bone marrow biopsy specimens, and other kind of blood cancer associated specimens, will review these specimens under the microscope. In addition, from that bone marrow biopsy specimen, we typically will send what’s called flow cytometry. So, looking at specific markers that may be seen on the leukemia cells. We will send molecular testing, so, looking for the genetic abnormalities that may be present in these leukemia cells. And we will send cytogenetic testing.
Typically, the cytogenetic testing can be done via what’s called karyotyping. So, looking at chromosomes under a microscope, and looking if big chunks of them are missing or swapped around. There’s also what we call FISH testing, which can look for more precise chromosomal abnormalities. But you have to know exactly what FISH abnormalities you’re looking for, because you have to pick what probes are sent to specifically evaluate for those abnormalities.
And in summary, those tests, typically, are what are necessary to arrive at a diagnosis of AML and also assign a risk stratification to someone’s AML