What is Acute Myeloid Leukemia (AML)?
Acute myeloid leukemia (AML) is a rare aggressive cancer of the blood and bone marrow. It is the most common form of acute leukemia in adults.
Normally, blood cells are made from stem cells (immature cells) in the bone marrow – the soft inner part of the bone. A blood stem cell can become either a myeloid stem cell or a lymphoid stem cell. A myeloid stem cell in healthy bone marrow can give rise to three different mature types of cells which together make up the blood. These include:
red blood cells – they give blood its red color and are responsible for carrying oxygen from the lungs to all parts of the body;
white blood cells – they fight infections and disease; and
platelets – they help blood to clot and prevent bleeding.
In AML, there is an abnormal production of one or more of these blood cells in the bone marrow due to certain changes in the genetic material (DNA). These are called genetic abnormalities. These abnormal cells are called leukemia cells and can fill up the bone marrow and spill into the blood, where they can spread to parts of the body including the brain, skin, spleen and gums. As a result, the production of normal blood cells is affected and the bone marrow cannot make enough healthy blood cells.
The most common signs and symptoms of AML include being short of breath, bruising, fever, weakness, and infection. Usually, AML develops quickly and becomes worse unless it is treated.
What are the causes of AML?
With AML, we do not fully understand why genetic abnormalities cause a blood cell to become abnormal. However, certain risk factors may increase the chance of developing AML. Having one or more of these risk factors does not mean you will develop AML, and someone without any of these risk factors can still develop AML. The possible risk factors for AML include the following:
Old age (AML is more common as people grow older, but AML can develop at any age)
Sex (AML is more common in men than women)
Being exposed to high-dose radiation or chemicals such as benzene (an industrial solvent), and some detergents
Previously having chemotherapy or radiotherapy for other cancers
Previously having a blood disease such as myelodysplastic syndrome
Having a genetic disorder that was present when you were born.
AML is not an inherited condition, it is not infectious, and it cannot be transferred from one person to another.
What tests might I have?
Several tests that examine the blood cells and bone marrow are used to detect and diagnose AML. These tests include the following:
This test is used to check the number of blood cells and to also look for abnormal blood cells using a microscope. An abnormal blood test can suggest a diagnosis of leukemia.
Bone marrow biopsy
A bone marrow sample is taken from inside the bone and examined under a microscope to look for changes in the blood cells. This test can be used to diagnose leukemia and to track the response to treatment.
Chromosomal studies (cytogenetics)
This test will be carried out to identify changes in the chromosomes. Chromosomes are bundles of DNA packaged within cells that contain the genetic code. There are normally 23 pairs of chromosomes in the human cell. In some instances, there may be chromosomal changes in abnormal blood cells in AML. Identifying these chromosomal changes can determine certain types of AML, which can help doctors decide on the most appropriate treatment.
This test can be used to examine the kinds of proteins (antigens) on the surface of the abnormal leukemia cells. This can help determine the specific type of AML.
Changes in the structure and function of genes called ‘genetic abnormalities’ could be the reason why abnormal leukemia cells develop. Identifying these, using molecular studies, can determine the specific type of AML.