Acute Myeloid Leukemia (AML)
Acute myeloid leukemia is a hematological cancer in which the bone marrow produces abnormal myeloid cells. Myeloid cells are immature blood cells that – in a healthy individual – eventually develop into fully functioning red blood cells, platelets or non-lymphocytic white blood cells. In individuals with leukemia, however, this normal development process is interrupted, and the immature cells continue to divide longer than they should. This typically leads to a buildup of abnormal myeloid cells in the bloodstream.
Acute myeloid leukemia is known by several other names, including:
- Acute myelogenous leukemia
- Acute granulocytic leukemia
- Acute non-lymphocytic leukemia
Acute myeloid leukemia may cause nonspecific symptoms such as fatigue, loss of appetite, unintended weight loss, fever, night sweats and joint pain. Additionally, as the AML cells rapidly divide and accumulate in the bone marrow, the cancerous cells may begin to crowd out healthy blood-making cells. As a result, acute myeloid leukemia can produce symptoms related to low blood cell and platelet counts.
Low red blood cell counts
Red blood cells play an essential role in delivering oxygen to tissues throughout the body. Acute myeloid leukemia can cause a shortage of healthy red blood cells that leads to anemia, which occurs when there are insufficient red blood cells to transport an adequate supply of oxygen to the body’s tissues. The symptoms of anemia include weakness, dizziness, rapid heartbeat, headache, skin pallor and shortness of breath.
Low white blood cell counts
A vital part of the immune system, white blood cells protect the body from infection by fighting off foreign invaders, such as viruses and bacteria. Acute myeloid leukemia can cause a shortage of infection-fighting white blood cells, leading to repeated or persistent infections. While the excess cells produced by AML may actually elevate the white blood cell count, the cancerous cells do not have the same infection-fighting capabilities as healthy white blood cells.
Low blood platelet counts
Platelets are tiny blood cells that help the body form clots to stop bleeding. Acute myeloid leukemia can cause a shortage of platelets. This condition, which is known as thrombocytopenia, can cause excessive bleeding, bruising, frequent nosebleeds, bleeding gums and heavy menstrual periods in women.
Because acute myeloid leukemia cells (blasts) are much larger than healthy white blood cells, the cancerous cells cannot easily pass through tiny blood vessels. As a result, blood vessels may become clogged, making it difficult for normal red blood cells and oxygen to reach tissues throughout the body. This relatively uncommon condition, which is known as leukostasis, is a medical emergency. Leukostasis can product stroke-like symptoms, such as slurred speech, blurred vision, confusion, headache, sleepiness and weakness on one side of the body.
Most symptoms of acute myeloid leukemia have other, less serious causes. Therefore, it is important to see a physician for testing, which is essential to an accurate diagnosis. To determine which type of diagnostic testing is most appropriate, a physician will consider the patient’s symptoms, age and overall health.
A physician may order blood testing to count the number of white blood cells present and examine the cells for abnormalities under a microscope. Special tests called flow cytometry (immunophenotyping) and cytochemistry are sometimes used to distinguish acute myeloid leukemia from other types of leukemia.
Bone marrow aspiration and biopsy
Bone marrow has both liquid and solid components. A bone marrow aspiration involves the use of a needle to remove a small sample of the fluid; a bone marrow biopsy involves the use of a needle to remove a small sample of the solid tissue. The tissue samples are then examined by a pathologist under a microscope. These tests are often performed together to check for bone marrow abnormalities. A common site for a bone marrow aspiration and biopsy is the pelvic bone, which is located in the lower back near the hip.
Molecular and genetic testing
Certain laboratory tests, such as cytochemical and immunohistochemical tests, can be performed to identify the specific genes involved in acute myeloid leukemia. This information is important because AML results from a series of mutations in a cell’s genes. After identifying the genes, a physician can determine the specific subtype of AML, which can influence the optimal course of treatment.
Imaging tests such as computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET) scans can help a physician learn more about the cause of symptoms or diagnose an infection in a patient with acute myeloid leukemia. Because AML has often spread throughout the bone marrow by the time it is diagnosed, imaging is not generally used to evaluate the spread of the cancer.
If a patient is experiencing symptoms that are indicative of AML spread to the brain or spinal cord, a physician may order a lumbar puncture, which involves the use of a needle to obtain a small sample of the cerebral spinal fluid (CSF). A pathologist then evaluates the makeup of the CSF to determine whether it contains leukemia cells or blood.
Although the precise causes of acute myeloid leukemia are not well understood, researchers have identified several factors that may increase the chance of developing AML. The risk factors for AML include:
- Smoking and other forms of tobacco use
- Exposure to benzene, which is found in tobacco smoke, petroleum and industrial workplaces
- Certain inherited genetic disorders, including Down syndrome, ataxia-telangiectasia, Li-Fraumeni syndrome, Klinefelter syndrome, Fanconi anemia, Wiskott-Aldrich syndrome, Bloom syndrome and familial platelet disorder syndrome
- Exposure to high levels of radiation
- Prior chemotherapy or radiation treatment
- Certain myeloproliferative bone marrow disorders, including polycythemia vera, myelofibrosis, essential thrombocytosis, myelodysplastic syndromes and aplastic anemia
Treatment for acute myeloid leukemia is typically divided into two phases: remission induction and consolidation.
The goal of the first phase of AML treatment is to induce remission by quickly destroying as many leukemia cells as possible. This is accomplished with an intensive round of chemotherapy that typically involves hospitalization. In addition to destroying leukemia cells, AML induction destroys most healthy bone marrow cells, resulting in extremely low blood counts. Therefore, many patients receive blood transfusions and antibiotic treatment during remission induction.
Approximately one week after the first round of chemotherapy is complete, a bone marrow biopsy is performed. In order for the AML to be considered in remission, the result should show few bone marrow cells (hypocellular bone marrow) and only a small portion of blasts. If the biopsy reveals leukemia cells in the bone marrow, another round of chemotherapy may be given.
Within a few weeks after the completion of treatment, normal bone marrow cells will return and begin producing new blood cells. During this time, a physician may perform one or more bone marrow biopsies to monitor the recovery of the blood cell counts.
Because remission induction usually does not destroy all leukemia cells, consolidation therapy is performed to help prevent the AML from returning over the next several months.
After remission is successfully induced, post-remission therapy is administered to attempt to destroy any remaining leukemia cells and help prevent a relapse. Depending on a patient’s age, overall health and risk factors, consolidation may involve chemotherapy or stem cell transplants.
At Moffitt Cancer Center, our Malignant Hematology Program provides comprehensive, individualized treatment for a range of blood and bone marrow cancers, including acute myeloid leukemia and other types of leukemia. We work consistently throughout each phase of a patient’s diagnosis, treatment and recovery to achieve the best possible outcomes – not only in terms of survival but also quality of life.
Starting with the very first consultation, our Malignant Hematology Program goes above and beyond to give each patient the best possible chance of achieving AML remission. Our multispecialty tumor board collaboratively considers a number of patient-specific factors to determine the most appropriate approach to remission induction therapy.
Acute myelogenous leukemia often requires long-term (consolidation) therapy to maintain positive outcomes. Bone marrow transplantation, secondary chemotherapy and other options may be suggested to help a patient achieve the best possible outcome and quality of life. And, to offer our patients an even broader selection of treatment options, we host a number of clinical trials, which present invaluable opportunities to access the newest AML treatments before they are available in other settings.
Medically reviewed by Jeffery Lancet, MD, Malignant Hematology.
Anyone who has been diagnosed with – or is experiencing symptoms of – acute myeloid leukemia can meet with a Moffitt oncologist with or without a physician’s referral. To request an appointment with an oncologist specializing in leukemia, call 1-888-663-3488 or submit a new patient registration form online.