Acute Myeloid Leukemia (AML)
Acute myeloid leukemia (AML) is a blood cancer. It happens when young abnormal white blood cells called blasts (leukemia cells), begin to fill up the bone marrow, preventing normal blood production. Doctors diagnose AML when 20 out of every 100 white blood cells in the bone marrow is a blast cell. AML is the most common acute leukemia affecting adults, with about 20,000 new cases diagnosed each year.
When people have AML, blasts make copies of themselves quickly. This slows the production of red blood cells and platelets, causing tiredness from anemia and a risk of bleeding from a low platelet count. There is also an increased risk of infection, since infection-fighting white blood cells are not maturing and cannot fight off infection.
AML is also known as acute myelogenous leukemia, acute myeloblastic leukemia and acute nonlymphocytic leukemia.
Relation to bone marrow failure diseases:
Over time, about one-third of all MDS cases evolve to become AML. The risk of developing AML depends largely on which MDS subtype you have at the time of diagnosis.
- A patient with lower-risk MDS has up to a 2 in 10 chance of developing AML.
- A patient with higher-risk MDS has more than a 4 in 10 chance of developing AML.
A smaller number of people with aplastic anemia and PNH go on to develop AML.
AML can occur at any age but is most common in older people. For most people with AML, there is no easily identifiable cause. There are, however, a few known risk factors that can increase the chances of getting AML. They include:
- Repeated exposure to the chemical benzene, as well as other chemicals like it called fluorocarbons, which are found in cigarette smoke, petroleum products and in certain industrial settings
- Certain uncommon genetic conditions such as Down syndrome, Fanconi anemia, dyskeratosis congenita, MonoMAC syndrome, Bloom syndrome, Shwachman syndrome and Diamond-Blackfan syndrome
- Having other blood cancers or disorders like polycythemia vera, primary myelofibrosis, essential thrombocythemia and myelodysplastic syndromes (MDS)
- Previous chemotherapy or radiation treatments for other cancers
The signs and symptoms of AML are mainly the result of low blood cell counts. Early in the disease, symptoms can mimic other common illnesses, like the flu. This may include fever, tiredness, loss of appetite and shortness of breath. As AML gets worse and more leukemia cells fill the bone marrow, symptoms may include:
- A pale complexion from anemia caused by a low red cell count
- Prolonged bleeding and easy bruising caused by a very low platelet count called thrombocytopenia, which may also include the appearance of pinhead-size red spots on the skin called petechiae
- Frequent infections caused by too few white cells called neutrophils
- Swollen gums
- Weight loss
- Discomfort in bones or joints
- Enlarged spleen
- Enlarged liver
More serious symptoms can include:
- Bleeding in the brain or lung
- Serious infections caused by too few white cells called neutrophils
- Myeloid sarcoma, a mass of AML cells that form a tumor in certain sites, such as the brain or spinal cord which can lead to neurological problems
An accurate diagnosis is important to guide treatment. Doctors use a number of tests to confirm an AML diagnosis and identify the patient’s AML subtype. These include:
- Physical exam and history
- Blood tests that include:
- A complete blood count with a differential that looks at the total number and type of blood cells in the blood
- A blood smear that allows a doctor to look at the blood under a microscope
- Bone marrow aspiration and biopsy are used to see how the bone marrow looks under a microscope and how many blast cells are present.
- Cytogenetic testing and molecular genetic testing that looks at abnormalities in the leukemia cell DNA.
Most patients with AML need treatment soon after diagnosis because the disease often progresses fast. The initial goal is to put the patient into remission. The long-term goal is to cure the disease, although this is not always possible.
Doctors use several types of therapy for adults with AML:
- Chemotherapy or other drug therapies are the first line of treatment. People with AML usually start chemotherapy right away. Some of the drugs most commonly used include cytarabine (also called cytosine arabinoside or ara-C.) and an anthracycline (such as daunorubicin or idarubicin).
- Stem cell transplantation may be used after chemotherapy as a second phase of treatment and may provide an opportunity for a cure.
- Clinical trials can involve therapy with new drugs and new drug combinations to increase the chance of first remission or new approaches to stem cell transplantation.
Other considerations that may impact treatment include:
- If the person is older than 70 or has other serious health issues (like a bad heart, lungs or kidneys): Some people in this category may not be as able to tolerate toxic chemotherapy drugs. Drugs such as decitabine or azacitidine or hydroxyurea may be better tolerated by older patients.
- If a child is being treated for AML: Therapy may differ slightly from that of the average adult.
- If the cancer has returned (relapsed) or is still present after the patient finishes standard therapy (refractory leukemia): There may be a different approach to treatment than the first time around.