Childhood Leukemia Overview

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Early Detection, Diagnosis, and Staging TOPICS

Classifying childhood leukemia

Most types of cancers are assigned numbered stages to describe their extent in the body, based on the size of the tumor and how far the cancer has spread. But leukemia is not staged like most other cancers. The cancer starts in the bone marrow and quickly spreads to the blood, so leukemia cells are already throughout the body. The major concern is whether the leukemia cells have also started to collect in other organs such as the liver, spleen, lymph nodes, or central nervous system (brain and spinal cord).

For instance, if the cancer cells have spread to the central nervous system in large numbers, they can be seen under a microscope in samples of the cerebrospinal fluid (CSF), the fluid that surrounds the brain and spine. If that has happened, treatment will need to be more intense in order to kill these cells.

The most important factor for leukemias is figuring out the type (such as ALL or AML) and subtype of the leukemia. This is done by testing samples of the blood, bone marrow, and sometimes lymph nodes or CSF. Figuring out the exact type and subtype of leukemia is a complex process that can be hard even for doctors to understand. For more detailed information, please see Childhood Leukemia.

Acute lymphocytic leukemia (ALL)

There are 4 main subtypes of ALL, based on the type of lymphocyte the leukemia cells come from and how mature they are. They are:

  • Early Pre-B cell
  • Pre-B cell
  • Mature B cell
  • T cell

Acute myelogenous leukemia (AML)

AML has many subtypes, based on the type of cell involved and how mature it is. The subtypes of AML are classified by how they look under the microscope and on the changes in the genes or chromosomes in the leukemia cells.

Hybrid or mixed leukemias

These leukemias have cells with features of both ALL and AML when they are tested in the lab. In children, these leukemias are generally treated like ALL and respond to treatment like ALL.

Chronic myelogenous leukemia (CML)

Chronic myelogenous leukemia (CML) is often a slower-growing cancer of early (immature) myeloid bone marrow cells. CML is not common in children, but it can occur.

The course of CML is divided into 3 phases, based mainly on the number of immature white blood cells (blasts) seen in the blood or bone marrow. If the leukemia is not cured with treatment, it can progress to more advanced phases over time.

  • Chronic phase
  • Accelerated phase
  • Blast phase (blast crisis)

If you have questions about what phase your child’s CML is in, be sure to have the doctor explain it to you.

Prognostic factors in childhood leukemia

Prognostic factors are important in helping the doctor decide whether to use standard treatment or more intense treatment. These factors refer to certain differences among patients that affect the response to treatment. Prognostic factors seem to be more important in ALL than in AML.

Prognostic factors for ALL

ALL is often classified as standard-risk, high-risk, or very high-risk. Children at higher-risk are given more intense treatment. As a rule, children with lower-risk ALL have a better outlook than those at very high risk.

There are many prognostic factors used to help classify ALL, but the first 2 are the most important. Keep in mind that many children with one or more poor factors can still be cured.

  • The child’s age when diagnosed
  • White blood cell count
  • Which subtype of ALL
  • The child’s gender and race
  • If the leukemia has spread to certain organs
  • If there are chromosome changes in the leukemia cells
  • How quickly the leukemia responds to treatment

Prognostic factors for AML

Prognostic factors are not quite as important for AML as they are for ALL. These factors can include:

  • The child’s age when diagnosed
  • White blood cell count
  • Whether the child has Down syndrome
  • The child’s body weight
  • Which subtype of AML
  • If there are certain chromosome changes in the leukemia cells
  • Whether the leukemia is a result of treatment for another cancer
  • How quickly the leukemia responds to treatment

For more detailed information on these factors, please see Childhood Leukemia.

Last Medical Review: 11/11/2013
Last Revised: 02/03/2014