Childhood acute lymphoblastic leukemia (ALL) is a type of cancer in which the bone marrow makes too many immature lymphocytes (a type of white blood cell).
Childhood acute lymphoblastic leukemia (also called acute lymphocytic leukemia or ALL) is a cancer of the blood and bone marrow. This type of cancer usually gets worse quickly if it is not treated. It is the most common type of cancer in children.
Normally, the bone marrow makes blood stem cells (immature cells) that develop into mature blood cells over time. A blood stem cell may become a myeloid stem cell or a lymphoid stem cell.
The myeloid stem cell develops into one of three types of mature blood cells:
The lymphoid stem cell develops into a lymphoblast cell and then into one of three types of lymphocytes (white blood cells):
- B lymphocytes that make antibodies to help fight infection.
- T lymphocytes that help B lymphocytes make the antibodies that help fight infection
- Natural killer cells that attack cancer cells and viruses.
In ALL, too many stem cells develop into lymphoblasts and do not mature to become lymphocytes. These lymphoblasts are called leukemia cells. The leukemia cells do not work like normal lymphocytes and are not able to fight infection very well. Also, as the number of leukemia cells increases in the blood and bone marrow, there is less room for healthy white blood cells, red blood cells, and platelets. This may lead to infection, anemia, and easy bleeding.
There are subgroups of childhood ALL.
There are different subgroups of ALL based on the following:
- Whether the type of blood cell that is affected looks more like a B lymphocyte or a
- The age of the child at diagnosis. For example, whether the child is younger than
one year, one year to 10 years old, or older than 10 years (teenager).
- Whether there are certain changes in the chromosomes. Philadelphia
chromosome -positive ALL is one type of chromosome change that may occur.
Family history and exposure to radiation may affect the risk of developing childhood ALL.
Anything that increases your risk of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn’t mean that you will not get cancer. People who think they may be at risk should discuss this with their doctor. Possible risk factors for ALL include the following:
- Having a brother or sister with leukemia.
- Being white or Hispanic.
- Living in the United States.
- Being exposed to x-rays before birth.
- Being exposed to radiation.
- Past treatment with chemotherapy or other drugs that weaken the immune system.
- Having certain changes in genes or genetic disorders, such as Down syndrome.
Possible signs of childhood ALL include fever and bruising.
These and other symptoms may be caused by childhood ALL. Other conditions may cause the same symptoms. A doctor should be consulted if any of the following problems occur:
Tests that examine the blood and bone marrow are used to detect and diagnose childhood ALL.
The following tests and procedures may be used:
Certain factors affect prognosis (chance of recovery) and treatment options.
The prognosis (chance of recovery) and treatment options may depend on:
If leukemia recurs (comes back) after initial treatment, the prognosis and treatment options may depend on:
Once childhood ALL has been diagnosed, tests are done to find out if the cancer has spread to the central nervous system (brain and spinal cord), testicles, or to other parts of the body.
The extent or spread of cancer is usually described as stages. For childhood acut lymphoblastic leukemia (ALL), risk groups are used instead of stages. The following tests and procedures may be used to determine the risk group:
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:
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.
In childhood ALL, risk groups are used instead of stages.
Because ALL is a disease of the blood cells, it has already spread throughout the body at diagnosis. There is no staging system for ALL. Risk groups are used to plan treatment.
Risk groups are described as:
Other factors that affect the risk group include the following:
It is important to know the risk group in order to plan treatment. Children with high-risk ALL usually receive more aggressive treatment than children with standard risk ALL.
Recurrent childhood ALL is cancer that has recurred (come back) after it has been treated. The leukemia may come back in the blood and bone marrow, brain, testicles, spinal cord, or in other parts of the body.
National Cancer Institute