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Acute Myeloid Leukemia (AML), Diagnosis and Treatment
Acute myeloid leukemia (AML) is a blood cancer that starts in the bone marrow and spreads to the blood. In AML, the body overproduces immature blood cells that, unable to function properly, end up crowding out healthy blood cells. As their number builds, they prevent normal blood cells from carrying out their essential functions.
What is AML?
AML is a fast spreading, aggressive type of leukemia that begins in the bone marrow and spreads into the blood, and sometimes other organs like the spleen, liver, testicles, central nervous system and lymph nodes. In AML, the bone marrow makes too many abnormal, immature white blood cells called myeloblasts that can't go on to become healthy white blood cells. In rare cases, it isn't myeloblasts, but abnormal immature red blood and platelet cells that are overproduced by the bone marrow.
AML is also known as acute myeloblastic leukemia, acute myelogenous leukemia, acute nonlymphocytic leukemia, acute granulocytic leukemia and acute non-lymphocytic leukemia (ANLL). Unlike most other cancers, AML does not form tumors in the body.
AML is classed according to how mature the abnormal cells are when the disease is diagnosed and how dissimilar those cells are from healthy cells.1
Who gets AML and how?
AML is one of the most common kinds of blood cancers, but still a rare disease and accounts for only one percent of all cancers. Only about 4.3 persons in every 100,000 will develop AML in their lifetimes.2
The exact cause of AML is unknown, but its development is a result of DNA changes in normal bone marrow cells. There are certain factors that predispose a person to developing AML. They include:
- Age: AML can develop at any age, but is uncommon in persons younger than 60
- Sex: AML is more common in men than women
- Family history: Having close relatives (a sibling or parent) with AML or other forms of leukemia increases the risk of developing AML. Having an identical twin with AML carries a significantly high risk.
- Genetic syndromes or inherited conditions: Having conditions or disorders like Down syndrome, Aplastic anemia, Fanconi anemia Kostmann syndrome and Li-Fraumeni syndrome increase the chances of developing AML.
- Medical history: A person has a higher risk of getting AML if one has a history of blood disorders like polycythemia vera, essential thrombocythemia and myelodysplastic syndrome exist.
- Exposure to radiation
- Exposure to benzene
- Having received chemotherapy treatment for a previous cancer3
What are the symptoms of AML?
The symptoms of AML are non-specific and are similar to those of many other conditions and diseases. They include:
- Petechiae—small circular brown patches caused by bleeding under the skin
- Decreased appetite
- Bone and joint pain
- Easily bruised skin
- Frequent nosebleeds
- Bleeding of gums
- Pale skin4
How is AML diagnosed?
In addition to a physical examination and medical history investigation, some tests that may be ordered to diagnose AML include:
- Complete blood count to check for the number of blood cells—red blood cells, white blood cells and platelets—in the body.
- Peripheral blood smear to check for the presence of blasts (immature cells) in the blood. Their presence in the blood is an indicator of AML, as they are usually confined to circulating in the bone marrow.
- Bone marrow aspiration and biopsies are done to obtain samples of the bone marrow for examination.
- Lumbar puncture to obtain cerebrospinal fluid. The fluid is checked for blood cancer cells and this is only done when it’s suspected that the cancer has spread to the brain and spinal cord.
- Chromosome tests like Polymerase Chain Reaction (PCR), Cytogenetics and Fluorescent in situ Hybridization (FISH) to check for chromosomal changes that are characteristic of AML.
Some of these diagnostic tests also help to classify AML and predict a patient's prognosis.5, 6
Can AML be treated?
AML can be treated successfully, especially if it's diagnosed early. Treatment takes place in two phases. The first, remission induction therapy, is targeted at destroying leukemia cells in the bone marrow and blood and putting the disease into remission. The second, post-remission therapy, is targeted at killing any remaining, inactive leukemia cells that have the potential to cause a future relapse.
Therapies used in both phases of treatment include:
- Bone marrow transplant
- Targeted therapy drugs
- Radiation therapy7
The treatment approach used for children is usually moderately different from the approach taken with adults. This is because the genetic features of AML in children is significantly different from those of AML in adults. In fact, they are sometimes referred to as two distinct conditions.8
(1) The National Institutes of Health. MedlinePlus. Acute Myeloid Leukemia https://medlineplus.gov/acutemyeloidleukemia.html
(2) (5) (7)National Cancer Institute. Adult Acute Myeloid Leukemia Treatment (PDQ®)–Patient Version https://www.cancer.gov/types/leukemia/patient/adult-aml-treatment-pdq
(3) American Cancer Society. Acute Myeloid Leukemia (AML). https://www.cancer.org/cancer/acute-myeloid-leukemia/causes-risks-prevention/risk-factors.html
(4)American Cancer Society. Signs and Symptoms of Acute Myeloid Leukemia (AML). https://www.cancer.org/cancer/acute-myeloid-leukemia/detection-diagnosis-staging/signs-symptoms.html
(6)American Cancer Society. Tests for Acute Myeloid Leukemia (AML) https://www.cancer.org/cancer/acute-myeloid-leukemia/detection-diagnosis-staging/how-diagnosed.html
(8)National Cancer Institute. TARGET Study Finds Major Differences between Childhood and Adult AML https://www.cancer.gov/news-events/cancer-currents-blog/2018/genetic-differences-childhood-adult-aml