Acute myeloid leukemia

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at February 26, 2016
StartDiseasesAcute myeloid leukemia

Acute myeloid leukemia (AML) also known as acute myelocytic leukemia, acute myelogenous leukemia, acute granulocytic leukemia, or acute non-lymphocytic leukemia, is a type of leukemia most commonly found in older adults. The initial symptoms can be similar to the flu. There are factors that can increase the risk of developing AML but in most cases there is no definitive cause. There are treatments available that increase the risk of survival if AML is diagnosed in its early stages.

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Definition & Facts

AML is a cancer that affects the blood and blood marrow. The term 'acute' means that this leukemia can spread quickly if not treated. 'Myeloid' refers to the kinds of cells - the myeloid stem cells - in which the cancerous abnormality begins. Bone marrow is the spongy substance inside the bones that creates blood cells.

AML occurs when the myeloid stem cells begins to create abnormal white blood cells, red blood cells, or platelets which are then called leukemic cells. In most cases, myeloid stem cells become immature myeloid blasts, a type of white blood cell.

There are several different types of AML, and most are defined by which cell types are being abnormally produced and how those cells differ from normal cells. If not treated quickly death can occur within weeks of onset. AML is uncommon in adults younger than 45, with the average age of diagnosis at 65.

Symptoms & Complaints

The early symptoms of AML can be quite similar to influenza. Generalized symptoms include:

Many of the symptoms of AML are caused by the replacement of normal cells with abnormal cells which are larger than normal cells and can block the blood from reaching all the tissue of the body. As the cancerous cells spread to other parts of the body it can show up as swelling in the abdomen, bleeding of the gums, rash-like bumps on the skin, facial numbness or blurred vision.

The lack of normal cells, particularly white blood cells, causes the patient to become vulnerable to infection. Patients with AML may become sick frequently or not recover from illness. As the number of healthy blood cells decreases, fatigue, anemia, and weakness increase in the patient.

Causes

There is no one definitive cause of AML; however, there are some common risk factors and substances that can contribute to its development. Such as:

  • Smoking - the only known lifestyle risk factor. Chemicals in tobacco smoke are known to travel through the bloodstream, affecting bone marrow.
  • Exposure to certain chemicals, such as benzene, is known to increase the risk of developing AML. Benzene is found in the rubber industry, oil refineries, chemical plants, shoe manufacturing, cigarette smoke, gasoline, motor vehicle exhaust, certain glues, cleaning products, detergents, art supplies, and paints.
  • Certain chemotherapy drugs – AML can develop around eight years after taking the drugs.
  • Radiation exposure – People exposed to a nuclear explosion or reactor meltdown have an increased risk of developing AML. Exposure to X-ray radiation has not produced conclusive data linking it to AML.
  • Certain blood disorders – Chronic myeloproliferative disorders particularly if the individual has also received chemotherapy treatments.
  • Other factors to be considered are age, gender because males are more likely to develop AML, and family history of AML.

Diagnosis & Tests

AML is initially diagnosed through taking a medical history and physical examination. If symptoms such as anemia, infection, bleeding or bruising indicate AML, a physician may order a complete blood count to discover the exact number of abnormal blood cells. Bone marrow samples may be taken as bone marrow may show abnormalities before they appear in the blood. Cerebrospinal fluid that surrounds the brain and spinal cord may be tested as AML can spread to these areas.

To pinpoint the exact type of AML additional tests may be run; which could include: blood chemistry test and coagulation testing; cytochemistry test, which exposes cells to chemical dyes; flow cytometry and immunohistochemistry; or cytogenetics which examines a cell's chromosomes and help indicate the type of AML. Some of these tests are used to diagnose AML, particularly which kind of AML the patient has, and others can be used to determine if treatments are working.

Treatment & Therapy

When beginning treatment the age, health, and other factors are taken into account to identify the most potentially successful treatment. Treatment of most types of AML is divided into two phases. Phase 1, called remission induction or just induction, focuses on ridding the body of as many leukemia cells as possible. Physicians try to determine chromosomal or genetic factors to determine the best course of treatment. The induction phase uses a combination of two or more chemo drugs.

In rare cases where the AML has spread to the brain and spinal column, radiation therapy may also be used. Phase 1 usually does not destroy all of the leukemia cells, thus the importance of phase 2: consolidation or post remission therapy. Phase 2 works to destroy the remaining leukemia cells. Consolidation usually uses only one drug, cytarabine. It is given over five days in a very high dosage. This is repeated over a series of several weeks. Another option in phase 2 is a stem cell transplant. Stem cell transplants, however, can be particularly risky for older patients.

Prevention & Prophylaxis

A clear cause of AML is not known which makes prevention difficult. Because most people do not have changeable risk factors there is no proven way to prevent AML. However, smoking is the most controllable risk factor; quitting smoking can reduce the risk of developing AML as well as many other types of cancers.

Avoidance of carcinogenic chemicals in the work or home environment is another small way to prevent the development of AML. Physicians weigh the risk of chemotherapy treatments in other types of cancer because these treatments can cause AML.