What is Acute Myeloid Leukemia (AML)?

Acute myeloid leukemia is a fast-growing cancer that affects the blood and bone marrow. The cancer occurs when immature blood-forming cells (myeloblasts) in the bone marrow grow uncontrollably, crowding out healthy red blood cells, white blood cells and platelets.

AML is one of the most common types of leukemia in adults, though it is relatively rare overall. Due to its rapid progression, an early diagnosis and treatment are essential to achieve the best possible outcome and quality of life.

What are the types of acute myeloid leukemia?

AML can be classified into several types based on the characteristics of the cancerous cells and their origin in the bone marrow. Physicians use this important information to guide diagnostic and treatment decisions.

The main types of acute myeloid leukemia are:

• AML with genetic abnormalities – The cancerous cells have specific chromosomal mutations or gene rearrangements, such as those affecting the RUNX1-RUNX1T1 or PML-RARA genes.
• AML with myelodysplasia-related changes – Often associated with complex genetic abnormalities, this type of AML may affect individuals with a history of myelodysplastic syndromes (MDS) or other blood disorders.
• Therapy-related AML – Associated with prior cancer treatment, this type of acute myeloid leukemia may develop after chemotherapy or radiation treatment.
• AML not otherwise specified (NOS) – This broad category of AML includes subtypes classified by the type of cell affected (e.g., myeloblastic, monoblastic or erythroid leukemia) when no specific genetic or secondary causes are identified.
• Acute promyelocytic leukemia (APL) – Characterized by an increased risk of bleeding and clotting complications, APL is caused by a translocation between chromosomes 15 and 17 (PML-RARA fusion gene) and is often highly treatable with targeted therapy.
• AML with minimal differentiation – Immature leukemia cells show little to no differentiation into normal blood cell types, making them difficult to classify into standard AML categories.
• Myeloid sarcoma – In this rare form of AML, the abnormal cells form solid tumors outside the bone marrow, such as in the skin or lymph nodes.

What causes acute myeloid leukemia?

AML is caused by genetic mutations in the DNA of myeloblasts that interfere with their normal development. The mutations cause the cells to multiply uncontrollably and fail to mature into healthy blood cells, leading to an accumulation of abnormal cells in the bone marrow and bloodstream.

What are the risk factors for acute myeloid leukemia?

Although the precise causes of the genetic mutations that lead to AML are not well understood, researchers have identified several factors that may increase the risk. These include:

• Advanced age – AML is most common in older adults, particularly those over 60, although it can also affect younger adults and children.
• Previous cancer treatment – Chemotherapy or radiation therapy for another cancer may increase the risk of developing acute myeloid leukemia.
• Exposure to carcinogenic chemicals – Prolonged exposure to benzene, which is found in tobacco smoke, petroleum and industrial settings, has been linked to AML.
• Tobacco use – Smoking introduces harmful chemicals directly into the body, which may contribute to DNA damage in blood cells.
• Genetics – A family history of AML or certain inherited genetic conditions, such as Down syndrome, ataxia-telangiectasia, Li-Fraumeni syndrome, Klinefelter syndrome, Fanconi anemia, Wiskott-Aldrich syndrome, Bloom syndrome and familial platelet disorder syndrome, can increase the risk of acute myeloid leukemia.
• Other conditions – Certain blood disorders that affect the bone marrow, such as polycythemia vera, myelofibrosis, essential thrombocytosis, MDS and aplastic anemia, can progress to AML over time.

Rated High Performing in Leukemia, Lymphoma & Myeloma

Recognized in U.S. News & World Report's Best Hospitals for significantly better performance in leukemia, lymphoma and myeloma treatment than the national average.

Schedule an Appointment

What are the symptoms of acute myeloid leukemia?

Like other types of leukemia, AML often causes nonspecific symptoms, such as:

• Fatigue
• Loss of appetite
• Unintended weight loss
• Fever and night sweats
• Bone and joint pain

Additionally, as the leukemia cells rapidly reproduce, they may begin to accumulate in the bone marrow and crowd out healthy blood-forming cells. As a result, acute myeloid leukemia can cause symptoms related to low blood cell and platelet counts. These include:

Low red blood cell counts

Red blood cells play an essential role in delivering oxygen and nutrients to vital organs and 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. Symptoms of anemia can include:

• Weakness
• Dizziness
• Rapid heartbeat
• Headaches
• Skin pallor
• 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 persistent or recurrent infections. In some cases, the excess cells produced by AML may deceptively elevate white blood cell counts, but 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 control bleeding. Acute myeloid leukemia can cause a shortage of platelets (thrombocytopenia). Symptoms can include:

• Excessive bleeding
• Easy bruising
• Frequent nosebleeds
• Bleeding gums
• Heavy menstrual periods in women

Leukostasis

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. Known as leukostasis, this relatively uncommon condition is a medical emergency. Symptoms often mimic those of a stroke, such as:

• Slurred speech
• Blurred vision
• Mental confusion
• Headaches
• Sleepiness
• Weakness on one side of the body

Florida's #1 Cancer Hospital

Ranked #1 Hospital for Cancer Care in U.S. News & World Report's list of America's Best Hospitals in Florida and ranked #23 in the Nation.

Schedule an Appointment

How is acute myeloid leukemia diagnosed?

Most AML symptoms can have other, less serious causes. Therefore, it is important to see a physician who can provide a prompt evaluation and accurate diagnosis. To determine which type of diagnostic testing is needed, the physician will consider several factors, including the patient’s symptoms, age and overall health. Tests commonly used to diagnose acute myeloid leukemia include:

Lab work

The physician may order blood testing to check the white blood cell count and microscopically examine the cells for abnormalities. Additionally, to differentiate AML from other types of leukemia, the physician may order molecular or genetic testing, such as:

• Flow cytometry (immunophenotyping) – This blood test uses antibodies to identify specific markers on the surface of leukemia cells, helping to classify the type of leukemia accurately.
• Cytochemistry – This staining process uses chemicals to identify enzyme activity or other cellular characteristics of leukemia cells, aiding in the diagnosis and classification of AML.

Bone marrow aspiration and biopsy

Because bone marrow has both liquid and solid components, testing for abnormalities often involves two procedures performed together: a bone marrow aspiration to extract a small sample of liquid and a bone marrow biopsy to remove a small sample of solid tissue. Both samples are then examined under a microscope by a pathologist. The pelvic bone, which is located in the lower back near the hip, is the most common site for bone marrow aspiration and biopsy.

Imaging

Because acute myeloid leukemia usually involves widespread bone marrow involvement by the time it is diagnosed, imaging is not commonly used to assess the extent of cancer spread. However, imaging tests such as computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET) scans can help the physician investigate the cause of symptoms or detect infection in a patient with AML.

Lumbar puncture

If symptoms suggest AML spread to the brain or spinal cord, the physician may order a lumbar puncture. Also known as a spinal tap, this procedure involves the use of a hollow needle to obtain a small sample of cerebral spinal fluid (CSF) for microscopic examination by a pathologist, who can identify cancerous cells.

How is acute myeloid leukemia treated?

AML treatment typically involves a combination of therapies aimed at eliminating the leukemia cells, achieving remission and preventing cancer recurrence. Common treatment approaches include:

Chemotherapy

Chemotherapy is the primary treatment for acute myeloid leukemia. Typically, it is administered in two phases: remission induction therapy and consolidation therapy.

Remission induction therapy

The goal of the first phase of AML treatment is to induce cancer remission by quickly destroying as many leukemia cells as possible. This is accomplished with an intensive round of chemotherapy that usually involves hospitalization. In addition to destroying leukemia cells, AML induction therapy will destroy most healthy bone marrow cells, resulting in extremely low blood cell counts. Therefore, many patients receive blood transfusions and antibiotics during this phase of treatment.

Approximately one week after the first round of induction chemotherapy is completed, the physician will perform a bone marrow biopsy. For acute myeloid leukemia to be considered in remission, the biopsy result should show very few bone marrow cells (hypocellular bone marrow) and only a small amount of myeloblasts. If the biopsy detects leukemia cells in the bone marrow, another round of chemotherapy may be given.

A few weeks after treatment is completed, normal bone marrow cells should return and begin to produce new blood cells. During this time, a physician may perform one or more bone marrow biopsies to monitor the recovery of blood cell counts.

While remission induction therapy is highly effective, it does not destroy all leukemia cells. Therefore, it is usually followed by the second phase of AML treatment—consolidation therapy—to help prevent the cancer from returning over the next several months.

Consolidation (maintenance) therapy

After acute myeloid leukemia remission is successfully induced and the patient has recovered from the first phase of treatment, post-remission chemotherapy will be administered to destroy any remaining leukemia cells and help prevent a relapse. Consolidation therapy may be accomplished with multiple courses of intensive chemotherapy or a combination of high-dose chemotherapy and bone marrow transplantation. The physician will determine the optimal approach based on the patient’s age, overall health and risk factors.

Bone marrow transplant

For high-risk or relapsed AML patients, bone marrow transplantation may be considered after chemotherapy. This complex and intensive procedure involves replacing the patient’s compromised bone marrow with healthy bone marrow from a donor. The transplant aims to restore the body’s ability to produce healthy blood cells and prevent the leukemia from returning. Although bone marrow transplantation carries certain risks, such as rejection of the transplanted cells and infection, it may offer a potential cure for a patient with an aggressive form of acute myeloid leukemia.

Targeted therapy

For certain patients, targeted therapy drugs may be administered to specifically attack leukemia cells by homing in on genetic mutations or abnormalities unique to those cells. This treatment approach can be particularly beneficial for patients with certain genetic markers, such as FLT3 or IDH mutations. Targeted therapy drugs work by interfering with the molecular processes necessary for leukemia cell survival and proliferation, providing a more precise treatment that may cause fewer side effects compared to traditional chemotherapy.

Radiation therapy

Though rarely used for treating acute myeloid leukemia, radiation therapy may be considered in specific situations. For example, it might be used to target leukemia cells that have spread to certain areas of the body, such as the brain and spinal cord. It can also be used as a preparatory step for a bone marrow transplant, aiming to destroy any remaining cancerous cells and create space for the transplanted cells. Radiation therapy may also be used to relieve symptoms in a case of localized AML.

Supportive care

In addition to the primary treatment options for acute myeloid leukemia, supportive care often plays an essential role in managing the side effects of intensive chemotherapy and bone marrow transplantation. To maintain the patient’s overall well-being and support recovery, the physician may suggest blood transfusions to address low blood cell counts, antibiotics to prevent or treat infections and medications to control pain or manage other complications, such as nausea.

Benefit from world-class care at Moffitt Cancer Center

Moffitt’s nationally renowned Malignant Hematology Program offers comprehensive, individualized care for a full range of blood and bone marrow cancers, including acute myeloid leukemia and other types of leukemia. As a National Cancer Institute-designated Comprehensive Cancer Center, we are recognized for our important research initiatives that continue to shape the future of cancer care. Through our robust portfolio of clinical trials, our patients have invaluable opportunities to access groundbreaking new AML treatments before those options are made available in other settings.

If you would like to learn more about acute myeloid leukemia, you can request an appointment with a leukemia specialist at Moffitt by calling 1-888-663-3488  or submitting a new patient registration form online. We do not require referrals.