Stages of Childhood Acute Myeloid Leukemia and Other Myeloid Malignancies

Once childhood acute myeloid leukemia (AML) has been diagnosed, tests are done to find out if the cancer has spread to other parts of the body.

The extent or spread of cancer is usually described as stages. In childhood acute myeloid leukemia (AML), the subtype of AML and whether the leukemia has spread outside the blood and bone marrow are used, instead of the stage, to plan treatment. The following tests and procedures may be used to determine if the leukemia has spread:

• Lumbar puncture: A procedure used to collect cerebrospinal fluid (CSF) from the spinal column. This is done by placing a needle into the spinal column. This procedure is also called an LP or spinal tap.
• Biopsy of the testicles, ovaries, or skin: The removal of cells or tissues from the testicles, ovaries, or skin so they can be viewed under a microscope to check for signs of cancer. This is done only if something unusual about the testicles, ovaries, or skin is found during the physical exam.

There are three ways that cancer spreads in the body.

When cancer cells spread outside the blood, a solid tumor may form. This process is called metastasis. The three ways that cancer cells spread in the body are:

• Through the blood. Cancer cells travel through the blood, invade solid tissues in the body, such as the brain or heart, and form a solid tumor.
• Through the lymph system. Cancer cells invade the lymph system, travel through the lymph vessels, and form a solid tumor in other parts of the body.
• Through solid tissue. Cancer cells that have formed a solid tumor spread to tissues in the surrounding area.

The new (metastatic) tumor is the same type of cancer as the primary cancer. For example, if leukemia cells spread to the brain, the cancer cells in the brain are actually leukemia cells. The disease is metastatic leukemia, not brain cancer.

There is no standard staging system for childhood AML, childhood chronic myelogenous leukemia (CML), juvenile myelomonocytic leukemia (JMML), transient myeloproliferative disorder (TMD), or myelodysplastic syndromes (MDS).

Childhood AML is described as newly diagnosed, in remission, or recurrent.

Newly diagnosed childhood AML

Newly diagnosed childhood AML has not been treated except to relieve symptoms such as fever, bleeding, or pain, and one of the following is true:

• More than 20% of the cells in the bone marrow are blasts (leukemia cells).

  or

• Less than 20% of the cells in the bone marrow are blasts and there is a specific change in the chromosome.

Childhood AML in remission

In childhood AML in remission, the disease has been treated and the following are true:

• The complete blood count is almost normal.
• Less than 5% of the cells in the bone marrow are blasts (leukemia cells).
• There are no signs or symptoms of leukemia in the brain, spinal cord, or other parts of the body.