Acute Myelogenous Leukemia

Definition

Acute myelogenous leukemia (AML) is a cancer of the blood and bone marrow. With AML, the bone marrow makes abnormal blood cells including:

• Myeloblasts—a type of white blood cell, fight infection
• Red blood cells (RBCs)—carry oxygen
• Platelets—makes blood clot, stops bleeding in cuts or bruises

AML begins in immature myeloblasts and progresses very quickly. It may also be the end state of chronic myelogenous leukemia (CML). AML may occur in either children or adults.

Cancer occurs when cells in the body become abnormal. They divide without control or order. Leukemia is cancer of the white blood cells and their parent cells. Leukemia cells do not function normally. They cannot do what normal blood cells do. In this case they can not fight infections. This means that the person is more likely to become infected with viruses or bacteria. The cancerous cells also overgrow the bone marrow. This forces other normal components, like platelets out. Platelets are needed to help the blood clot. As a results people with leukemia may bleed more easily.

Causes

The cause of AML is unknown. However, smoking after age 60 doubles the risk of this condition.

Risk Factors

The following factors increase your chance of developing AML:

• Sex: male
• Smoking, especially after age 60
• Previous chemotherapy or radiation therapy treatment
• Previous treatment for childhood acute lymphoblastic leukemia (ALL) , Hodgkin’s disease , non-Hodgkin’s lymphoma , and certain other cancers
• Exposure to atomic bomb radiation or nuclear reactor accident
• Exposure to the chemical benzene
• History of a blood disorder, such as myelodysplastic syndrome (precancerous changes in the white cells and precursor cells of the bone marrow)

The following risk factors are specific to childhood AML:

• Having a brother or sister with leukemia
• Race: Hispanic
• Exposure to cigarette smoke or alcohol before birth
• History of myelodysplastic syndrome or aplastic anemia
• Previous chemotherapy or radiation therapy treatment
• Exposure to ionizing radiation
• Exposure to chemicals such as benzene
• Certain genetic disorders, such as Down’s syndrome

Symptoms

These may also be caused by other, less serious health conditions. See a doctor if you have any of the following:

• Fever
• Shortness of breath
• Paleness (a sign of anemia )
• Easy bruising or bleeding
• Petechiae (flat, pinpoint spots under the skin caused by bleeding)
• Weakness
• Tiredness
• Loss of appetite
• Weight loss
• Bone pain
• Joint pain
• Enlargement of the liver and spleen
• Swelling, pain, and bleeding of the gums
• Painless lumps in the neck, underarms, stomach, or groin

Diagnosis

Your doctor will ask about your symptoms and medical history. A physical exam will be done. Swelling of the liver; spleen will be looked for. The doctor will also look for swelling in lymph nodes in the armpits, groin, or neck. You will likely be referred to an oncologist. This is a doctor who focuses on treating cancer.

Tests may include the following:

• Blood tests—to check for changes in the number or appearance of different types of blood cells
• Bone marrow aspiration—removal of a sample of liquid bone marrow to test for cancer cells
• Bone marrow biopsy —removal of a sample of liquid bone marrow and a small piece of bone to test for cancer cells
• Spinal tap —removal of a small amount of cerebrospinal fluid to check for cancer cells
• Routine microscopic exam—examination of a sample of blood, bone marrow, lymph node tissue, or cerebrospinal fluid
• Bone, blood marrow, lymph node tissue, or cerebrospinal fluid tests—to distinguish between types of leukemia
• Cytogenetic analysis—a test to look for certain changes of the chromosomes (genetic material) of the lymphocytes
• Immunophenotyping—examination of the proteins on cell surfaces and the antibodies produced by the body; to distinguish lymphoblastic from myeloid leukemia and determine types of therapy
• Chest x-ray —x-rays of the chest that may detect signs of lung infection or cancer in the chest
• CT scan —a type of x-ray that uses a computer to make pictures of structures inside the body
• MRI scan —a test that uses magnetic waves to make pictures of structures inside the body
• Gallium scan and bone scan—injection of a radioactive chemical into the bloodstream to detect areas of cancer or infection
• Ultrasound —a test that uses sound waves to examine masses and organs inside the body

Once AML is identified, it can be classified as one of eight subtypes. These are based on the type of cell from which leukemia developed. Classification is important. It can help make a prognosis and design a treatment plan.

Treatment

Talk with your doctor about the best plan for you. Treatment of AML usually involves two phases:

• Remission induction therapy—to kill leukemia cells
• Maintenance therapy—to kill any remaining leukemia cells that could grow and cause a relapse

Treatment options include:

Chemotherapy

Chemotherapy is the use of drugs to kill cancer cells. It may be given in many forms. This includes pill, injection, and via a catheter. The drugs enter the bloodstream and travel through the body. While this will focus on cancer cells, some healthy cells are also killed.

Some AML may spread to the brain and spinal cord. In this case, intrathecal chemotherapy may be used. Chemotherapy drugs are placed directly into the spinal column.

Radiation Therapy

Radiation therapy involves the use of radiation to kill cancer cells and shrink tumors. For AML, external radiation therapy is used.

The radiation is directed at the tumor from outside the body. This type of treatment is used for AML that has spread, or may spread, to the brain and spinal cord. It can also be used to treat bone pain that comes from bone affected by the leukemia.

Chemotherapy With Stem Cell Transplant

Chemotherapy is followed by a transplantation of stem cells (immature blood cells). These will replace blood-forming cells destroyed by cancer treatment. Stem cells are removed from the blood or bone marrow of the patient or donor. They are then infused into the patient.

Other Drug Therapy

These drugs may be used with certain types of leukemia. They can kill leukemia cells, stop them from dividing, or help them mature into white blood cells:

• Arsenic trioxide
• All-trans retinoic acid (ATRA)

A targeted therapy has been approved by FDA. It is approved for patients older then 60 years who relapsed after initial therapy. The CD33 receptor on leukemia cells is targeted with:

• Gemtuzumab ozogamicin (Mylotarg)

Biologic Therapy

This is the use of medications or substances made by the body. The substance is used to increase or restore the body's natural defenses against cancer. This type of therapy is also called biological response modifier therapy. It is still being tested in clinical trials.

Treatment of Side Effects

Patients will suffer side effects not only from the leukemia, but from therapy. These include:

• A reduction in red blood cells (anemia)
• Reduced numbers of platelets that assist in blood clotting (thrombocytopenia)
• Decreased numbers of the white blood cells that fight infection

Anemia may lead to fatigue. If severe enough, it can complicate respiratory or cardiac disease. Thrombocytopenia may lead to bleeding and bruising. Decreased numbers of white blood cells leave a patient more vulnerable to infection.

Your doctor may prescribe a number of different treatments to decrease these side effects. Drugs are available to increase production of normal blood cells. In addition, when your counts are particularly low, blood transfusions or changes in daily activities may be needed. These step will reduce the chance of fatigue, bleeding, or infection.

Prevention

Many people who develop AML have no risk factors. There is no way to prevent the condition in most people. However, 20% of cases are related to smoking tobacco. Not smoking is the best known way to prevent AML.