Acute myeloid leukemia (AML) is a type of leukemia. It is also called acute myelogenous leukemia, acute myeloblastic leukemia, acute myelocytic leukemia, acute granulocytic leukemia, and acute nonlymphocytic leukemia.
Leukemia is a cancer of the blood cells that are produced and released into the circulation from the bone marrow. Bone marrow is the soft, inner part of bones where red and white blood cells and platelets are produced. The word "acute" in acute myeloid leukemia refers to the fact that the disease can progress quickly. Symptoms that lead to a diagnosis of AML occur over a relatively short period of time, often days to weeks.
There is also a more chronic type of myeloid leukemia called chronic myeloid or chronic myelogenous leukemia (CML), which has very different presentation and course than AML.
AML starts in the blood-forming cells of the bone marrow. These blood-forming cells are called myeloid stem cells. These earliest forms of cells, called stem cells, normally develop into:
- White blood cells, which fight infection and disease
- Red blood cells, which carry oxygen
- Platelets, which help prevent bleeding by causing blood to clot.
In most cases of AML, the stem cells develop into immature white blood cells (myeloblasts). The immature myeloblasts reproduce without becoming healthy, mature white blood cells. As the leukemia cells multiply in the bone marrow and blood, they crowd out healthy blood cells. This can lead to frequent infections, anemia, and easy bruising and bleeding.
Sometimes, too many myeloid stem cells develop into abnormal red blood cells or platelets.
Leukemia can involve tissues outside the bone marrow and blood, including lymph nodes, brain, skin and other parts of the body.
AML can happen at any age. But the risk increases with older age. Until age 50, men and women are equally affected. But older men are more likely to develop AML than older women for unclear reasons.
Symptoms
Among the possible signs and symptoms of AML are:
- Unexplained and persistent fever
- Marked fatigue and weakness
- Unexpected weight loss with poor appetite
- Easy bruising or bleeding
- Serious infections
Leukemia cells that spread to the brain and spinal cord can cause:
- Severe and persistent headache
- Seizures
- Trouble with balance
AML is not a common disease. So most often the above symptoms are caused by some other medical condition.
Diagnosis
If your doctor suspects leukemia, he or she will do a physical exam to check for signs of disease. He or she will ask about your medical history. This might include your health habits and past illnesses and treatment.
You will then undergo various tests and procedures to confirm the diagnosis. These tests may include:
- Blood tests – Several tests may be done using blood drawn from a vein in your arm. Your blood will be analyzed to count the numbers of different blood cells. Changes in your blood chemistry and in the appearance of your blood cells will be analyzed as well.
- Bone marrow aspiration and biopsy – A small sample of bone and liquid bone marrow will be taken from your hipbone or breastbone with a long needle. A specially trained doctor will examine the sample to look for abnormalities in the cells.
If the diagnosis is leukemia, you may be referred to a hematologist/oncologist. This is a doctor who specializes in cancers of the blood and bone marrow.
There are several subtypes of AML. The different AML subtypes have somewhat different symptoms, treatment approaches, and outlooks. You are likely to undergo additional tests to determine your subtype of AML.
These tests may include:
- Cytogenetic studies to look for certain changes in cells' genetic material.
- Immunophenotyping, a process that identifies leukemia cells based on specific substances on the cells' surface.
You may also need to undergo additional tests and procedures to determine whether the AML has spread to other parts of the body. These tests are likely to include imaging tests, such as a CT scan, MRI or lumbar puncture/spinal tap (which uses a needle to collect fluid from the spinal column).
Expected Duration
Acute myeloid leukemia can grow quickly and become life-threatening if it is not treated right away.
Prevention
There is no known way to prevent AML
However, several factors can increase a person's risk of developing adult AML. These include:
- Exposure to certain industrial chemicals such as benzene
- Previous cancer treatment with intensive chemotherapy and radiation therapy, especially for conditions such as Hodgkin's and non-Hodgkin's lymphoma and childhood acute lymphocytic leukemia
- Exposure to high-dose radiation (such as a nuclear reactor accident)
- A history of some blood disorders, including myelodysplastic syndromes (MDS)
- Some genetic disorders such as Down syndrome and Fanconi anemia
- Smoking.
Most people with AML do not have a known risk factor.
Treatment
Acute myeloid leukemia is usually described as:
- Untreated. Untreated AML is newly diagnosed.
- In remission. AML that is in remission has been treated. The patient does not currently have any signs or symptoms of leukemia.
- Recurrent (relapsed). Recurrent AML has been treated. It has come back after going into remission.
Refractory AML is leukemia that has not responded to the initial treatment.
A care team will recommend treatment based on several factors, including:
- Age of the patient.
- The subtype of AML.
- Whether the cancer has spread to the central nervous system (brain and spinal cord).
- Whether the patient has been treated in the past for another cancer.
- Whether the person has had a blood disorder such as myelodysplastic syndromes.
- Whether the AML has been treated before and come back.
When you are considering a treatment option, it's important to ask your doctor about the expected benefits and risks of a particular therapy.
There are usually two phases of treatment. The first phase aims to put the leukemia into remission. The second phase is intended to prevent a relapse.
In the first treatment phase, doctors kill as many leukemia cells in the blood and bone marrow as possible. After these abnormal cells are eliminated, the bone marrow is able to regenerate more normal cells that are not leukemia cells. When this phase is successful, the disease is considered to be in remission.
Standard treatment for AML involves chemotherapy to stop the growth of cancer cells. Chemotherapy for AML is usually given as combination chemotherapy. This means that more than one anticancer drug is used.
Chemotherapy can be taken by mouth or injected into a vein or muscle. It enters the bloodstream and travels throughout the body. Chemotherapy may also be injected directly into the fluid surrounding the brain and spinal cord. This may be done to treat adult AML that has or may spread to the central nervous system.
Chemotherapy treatments usually cause side effects. Your doctor can suggest ways to manage these side effects. Side effects may include:
- Hair loss
- Nausea
- Mouth sores
- Fatigue
- Increased risk of infection
- Bleeding.
In the second treatment phase, steps are taken to kill any remaining leukemia cells that could cause a relapse. The second phase of treatment may involve:
Radiation therapy uses high-energy radiation to kill cancer cells or stop them from growing. It can also help reduce pain in bone that has been affected by leukemia.
Another possible treatment for AML is a stem cell transplant. A stem cell transplant replaces a person's blood-forming cells. Stem cell transplants can use stem cells from your own body or from a donor. Donor stem cell transplant may be necessary if the patient's own stem cells are abnormal or have been destroyed by cancer treatment.
Stem cells (immature blood cells) are removed from the blood or bone marrow of a patient or donor. Once removed, they are examined under a microscope and the cell number is counted. The stem cells are stored for future use.
The patient then undergoes high-dose chemotherapy to eradicate the leukemic cells that populate the bone marrow. The stored stem cells are then infused into the patient's bloodstream. They migrate into the bone marrow space. Because these are stem cells, they are able to regenerate and grow into the many different cells that normally populate the bone marrow.
Stem cell transplants require very high dose chemotherapy to rid the body of all the leukemia. In the process, the patient cannot make any blood cells until the stem cells have had time to mature. This puts the patient at high risk of infection and bleeding. In addition to the short term risks, there are also long term side effects. Stem cell transplants should be undertaken only in specialized centers.
For older patients with AML, chemotherapy can be very debilitating. A new option for people with a specific cancer cell mutation is an oral drug called ivosidenib.
Treatment for recurrent AML in adults depends on the subtype. It may include chemotherapy, cell transplant, or other types of treatment.
Patients should continue to have regular follow-up exams and tests, even if they are in remission.
When To Call a Professional
Contact a doctor if you experience any of the symptoms of AML. Symptoms include:
- Unexplained and persistent fever
- Marked fatigue and weakness
- Unexpected weight loss with poor appetite
- Easy bruising or bleeding.
Prognosis
The outlook for adult AML depends on many factors including:
- Patient's age
- Subtype of AML based on the genetic makeup of the leukemia cells
- Presence and type of changes to the genetic material
- Levels of white blood cells
- Levels of platelet counts and whether there are any signs of serious bleeding
- Whether the cancer has spread to the central nervous system
- Whether the person has had a blood disorder such as myelodysplastic syndromes, which is a preleukemic condition
- Whether the illness is related to previous treatment for another cancer, such as radiation and chemotherapy
- Whether the AML has been treated before and come back
- The type of complications and recovery from complications during the chemotherapy administration of treatment.
Children with acute leukemia generally have a better prognosis than adults. Remission is very likely. However, the leukemia and the multiple drugs needed for treatment can affect growth, hormonal development and learning capabilities.