Acute myeloid leukemia (AML)
What is acute myeloid leukemia?
Acute myeloid leukemia, or acute myelogenous leukemia, is caused when early version of blood cells don’t grow normally and then invade the body. Cancer can affect red blood cells and platelets, but leukemia usually refers to the other component of blood – white blood cells. These are the blood cells that fight infections, viruses, and other diseases.
AML cells are immature blood cells (called blasts) and because of this are fast-growing. Normal blast cells divide quickly. Leukemia blast cells don’t divide faster than normal blast cells, but they do do continue dividing long after the normal blast cells have stopped. Without treatment, most patients with AML would live only a few months.
There are an estimated 19,950 new AML diagnoses each year, most of which are in adults. AML is generally a disease of older adults, and is uncommon for those younger than 45. The average age of a person diagnosed with AML is 67. It’s slightly more common in men than in women, but the overall risk for both genders is 0.5 to 1 percent.
What are the symptoms of AML?
Patients with AML typically have several general symptoms; that is, the symptoms of AML could be the same for any number of illnesses or disease. The most common are:
- Weight loss
- Night sweats
- Loss of appetite
Other symptoms—such as low numbers of normal blood cells—will be found only when your doctor either suspects leukemia or is drawing blood for other tests. Low normal blood cell counts occur when the leukemia cells grow too plentiful and crowd out the other cells. Additional symptoms of low red blood cells are:
- Feeling cold
- Dizziness or light-headedness
- Shortness of breath
It could be that the leukemia cells are crowding out the white blood cells, which would cause a patient not to heal properly. White blood cells fight infection, so if you have a shortage, your body can’t heal itself, or fight off colds, fever, or infection.
Leukemia cells may also crowd out platelets, the part of the blood that helps wounds stop bleeding. A shortage of platelets can cause:
- Easy bruising and bleeding
- Frequent, sometimes severe, nosebleeds
- Bleeding gums
How is AML diagnosed?
Many people with AML don’t have any symptoms when it’s diagnosed – it’s typically found when a doctor orders blood tests for something completely unrelated or during a routine checkup.
Some people may be at higher risk of AML because they have certain blood disorders, such as myelodysplastic syndrome, or inherited disorders, such as Down syndrome, or because they were treated with certain chemotherapy drugs or radiation. Doctors typically recommend these people have regular checkups.
If symptoms or a physical examination indicted you may have leukemia, the doctor will need to take samples of your blood and bone marrow to have it tested to be sure. The blood will be drawn from a vein in the arm, in most cases, but the bone marrow will be extracted in two ways: through an aspiration and a biopsy.
Bone aspiration and biopsy
The bone marrow aspiration and biopsy are done at the same time. Samples are generally taken from the back of the pelvic bone (hip), or sometimes from the sternum (breastbone) with a thin, hollow needle. A small piece of bone marrow is then tested in a lab for leukemia cells.
AML can sometimes spread to the brain and spinal cord, and for this reason your doctor may need to take a sample of spinal fluid for testing. The fluid will be extracted using a lumbar puncture, or spinal tap. This test is used only for patients whose symptoms may be caused by the leukemia spreading to the brain and spinal cord.
There are several lab tests that may be used to determine whether you have AML or how advanced the disease may be.
Imaging tests, like X-rays, computed tomography (CT) scans, magnetic resonance imaging (MRI) scans, and ultrasounds may be used to help doctors see detailed images inside your body.
How is AML staged?
Most cancer is staged according to the size of the tumor and the cancer’s progression, or how much it has spread. Stages are helpful in determining the prognosis, or outlook, for the patient.
AML, however, is a disease of the bone marrow and so it isn’t staged like most other cancers. Rather than it being about the size of the tumor and where it has spread, staging depends on other things The prognosis depends on other things, such as the subtype of the disease, age of the patient, and lab test results.
There are several classifications of AML, according to the World Health Organization (WHO). The WHO divides AML into several groups, according to the American Cancer Society:
- AML with certain genetic abnormalities
- AML with a translocation between chromosomes 8 and 21
- AML with a translocation or inversion in chromosome 16
- AML with a translocation between chromosomes 9 and 11
- APL (M3) with a translocation between chromosomes 15 and 17
- AML with a translocation between chromosomes 6 and 9
- AML with a translocation or inversion in chromosome 3
- AML (megakaryoblastic) with a translocation between chromosomes 1 and 22
- AML with myelodysplasia-related changes
- AML related to previous chemotherapy or radiation
- AML not otherwise specified (This includes cases of AML that don’t fall into one of the above groups, and is similar to the FAB classification.)
- AML with minimal differentiation (M0)
- AML without maturation (M1)
- AML with maturation (M2)
- Acute myelomonocytic leukemia (M4)
- Acute monocytic leukemia (M5)
- Acute erythroid leukemia (M6)
- Acute megakaryoblastic leukemia (M7)
- Acute basophilic leukemia
- Acute panmyelosis with fibrosis
- Myeloid sarcoma (also known as granulocytic sarcoma or chloroma)
- Myeloid proliferations related to Down syndrome
- Undifferentiated and biphenotypic acute leukemias (leukemias that have both lymphocytic and myeloid features). Sometimes called ALL with myeloid markers, AML with lymphoid markers, or mixed phenotype acute leukemias.
How is prognosis determined?
There are several factors that can help determine a patient’s prognosis, or outlook for survival, many of which can be helpful when choosing treatment. These factors will help the doctor determine if people with a certain type of AML should get more or less treatment. Some of these factors are:
- Chromosome abnormalities
- Gene mutations
- Genetic markers on the leukemia cells
- Patient’s age
- White blood cell count
- Prior blood disorder
- Treatment-related AML—that which occurs after the treatment of another cancer
- Leukemia cells in the central nervous system
- Status of AML after treatment
AML risk factors
What causes AML?
With many cancers, there are risk factors that you can control to increase or decrease your chances of getting the disease. A risk factor is something that affects your chances of getting as disease. Some risk factors can be changed to raise or lower a person’s risk of getting that disease. Others, like family history, are static and can’t be changed.
- Exposure to certain chemicals, such as benzene
- Certain chemotherapy drugs, such as alkylating agents and topoisomerase II inhibitors
- Radiation exposure, such as being a survivor of a nuclear reactor accident
- Certain blood disorders, such as polycythemia vera, essential thrombocythemia, and idiopathic myelofibrosis
- Genetic syndromes—some genetic mutations may cause AML. These syndromes include:
- Fanconi anemia
- Bloom syndrome
- Diamond-Blackfan anemia
- Schwachman-Diamond syndroms
- Li-Fraumeni syndrome
- Neurofibramatosis type 1
- Severe congenitalneutropenia
- Down syndrome
- Trisomy 8
- Family history
- Older age
- Male gender
Should I get screened for AML?
Unfortunately, there are no screening tests routinely available to detect AML in the early stages. However, AML is sometimes detected when certain symptoms show up in routine blood tests done for other reasons. For example, a person’s white blood cell count may be very low, even if there are no other symptoms. That may lead to other tests in which AML may be found.