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What is childhood acute lymphoblastic leukemia?
Childhood acute lymphoblastic leukemia (also called acute lymphocytic
leukemia or ALL) is a disease in which too many underdeveloped
infection-fighting white blood cells, called lymphocytes, are found in a child's
blood and bone marrow. ALL is the most common form of leukemia in children, and
the most common kind of childhood cancer.
Lymphocytes are made by the bone marrow and by other organs of the lymph
system. The bone marrow is the spongy tissue inside the large bones in the body.
The bone marrow makes red blood cells (which carry oxygen and other materials to
all tissues of the body), white blood cells (which fight infection), and
platelets (which make the blood clot). Normally, the bone marrow makes cells
called blasts that develop (mature) into several different types of blood cells
that have specific jobs to do in the body.
The lymph system is made up of thin tubes that branch, like blood vessels,
into all parts of the body. Lymph vessels carry lymph, a colorless, watery fluid
that contains lymphocytes. Along the network of vessels are groups of small,
bean-shaped organs called lymph nodes. Clusters of lymph nodes are found in the
underarm, pelvis, neck, and abdomen. The spleen (an organ in the upper abdomen
that makes lymphocytes and filters old blood cells from the blood), the thymus
(a small organ beneath the breastbone), and the tonsils (an organ in the throat)
are also part of the lymph system.
Lymphocytes fight infection by making substances called antibodies, which
attack germs and other harmful bacteria in the body. In ALL, the developing
lymphocytes become too numerous and do not mature. These immature lymphocytes
are then found in the blood and the bone marrow. They also collect in the lymph
tissues and make them swell. Lymphocytes may crowd out other blood cells in the
blood and bone marrow. If your child's bone marrow cannot make enough red blood
cells to carry oxygen, your child may have anemia. If your child's bone marrow
cannot make enough platelets to make the blood clot normally, your child may
bleed or bruise easily. The cancerous lymphocytes can also invade other organs,
the spinal cord, and the brain.
Leukemia can be acute (progressing quickly with many immature cancer cells)
or chronic (progressing slowly with more mature-looking leukemia cells). Acute
lymphoblastic leukemia progresses quickly, and can occur in both children and
adults. Treatment is different for adults than it is for children. Refer to the
PDQ patient information summary on Adult
Acute Lymphoblastic Leukemia Treatment for more information.
Early signs of ALL may be similar to those of the flu or other common
diseases, such as a fever that won't go away, feeling weak or tired all the
time, aching bones or joints, or swollen lymph nodes. If your child has symptoms
of leukemia, his or her doctor may order blood tests to count the number of each
of the different kinds of blood cells. If the results of the blood tests are not
normal, a bone marrow biopsy may be performed. During this test, a needle is
inserted into a bone in the hip and a small amount of bone marrow is removed and
examined under the microscope, enabling the doctor to determine what kind of
leukemia your child has and plan the best treatment.
Your child's doctor may also do a spinal tap, in which a needle is inserted
through the back to remove a sample of the fluid that surrounds the brain and
spine. The fluid is then examined under a microscope to see if leukemia cells
are present.
Your child's chance of recovery (prognosis) depends on your child's age at
diagnosis, the number of white blood cells in the blood (the white blood cell
count) at diagnosis, how far the disease has spread, the biologic
characteristics of the leukemia cells, and how well the leukemia cells respond
to treatment.
Stage Explanation
There is no staging for childhood acute lymphoblastic leukemia. The
treatment depends on age, the results of laboratory tests, and whether or not
the patient has been previously treated for leukemia.
Untreated
Untreated acute lymphoblastic leukemia (ALL) means that no treatment has
been given except to reduce symptoms. There are too many white blood cells in
the blood and bone marrow, and there may be other signs and symptoms of
leukemia.
In remission
Remission means that treatment has been given and the number of white blood
cells and other blood cells in the blood and bone marrow is normal. There are no
signs or symptoms of leukemia.
Recurrent/refractory
Recurrent disease means that the leukemia has come back (recurred) after
going into remission. Refractory disease means that the leukemia failed to go
into remission following treatment.
Treatment Option Overview
How childhood acute lymphoblastic leukemia is treated
There are treatments for all patients with childhood acute lymphoblastic
leukemia (ALL). The primary treatment for ALL is chemotherapy. Radiation therapy
may be used in certain cases. Bone marrow transplantation is being studied in
clinical trials.
- Chemotherapy: Chemotherapy uses drugs to kill cancer
cells. Chemotherapy drugs may be taken by mouth, or may be put into the body
by a needle in a vein or muscle. Chemotherapy is called a systemic treatment
because the drug enters the bloodstream, travels through the body, and can
kill cancer cells throughout the body. For ALL, chemotherapy drugs may
sometimes be injected (usually through the spine) into the fluid that
surrounds the brain and spinal cord; this is known as intrathecal
chemotherapy.
- Radiation Therapy: Radiation therapy uses x-rays or
other high-energy rays to kill cancer cells and shrink tumors. Radiation for
ALL usually comes from a machine outside the body (external beam radiation
therapy).
- Bone Marrow Transplantation: Bone marrow
transplantation is a newer type of treatment. First, high doses of
chemotherapy with or without radiation therapy are given to destroy all of
the bone marrow in the body. Healthy marrow is then taken from another
person (a donor) whose tissue is the same as or almost the same as the
patient's. The donor may be a twin (the best match), a brother or sister, or
another person not related to the patient. The healthy marrow from the donor
is given to the patient through a needle in a vein, and the marrow replaces
the marrow that was destroyed. A bone marrow transplant using marrow from a
relative or person not related to the patient is called an allogeneic bone
marrow transplant.
An even newer type of bone marrow transplant, called autologous bone marrow
transplant, is being studied in clinical trials. During this procedure, bone
marrow is taken from the patient and may be treated with drugs to kill any
cancer cells. The marrow is frozen to save it. The patient is then given
high-dose chemotherapy with or without radiation therapy to destroy all of the
remaining marrow. The frozen marrow that was saved is thawed and given through a
needle in a vein to replace the marrow that was destroyed.
Phases of treatment
There are generally 4 phases of treatment for ALL:
The first phase, remission induction therapy, uses
chemotherapy to kill as many of the leukemia cells as possible to cause the
cancer to go into remission.
The second phase, called central nervous system (CNS)
prophylaxis, is preventive therapy using intrathecal and/or high-dose
systemic chemotherapy to the CNS to kill any leukemia cells present there,
or to prevent the spread of cancer cells to the brain and spinal cord even
if no cancer has been detected there. Radiation therapy to the brain may
also be given, in addition to chemotherapy, for this purpose. CNS
prophylaxis is often given in conjunction with consolidation/intensification
therapy.
Once a child goes into remission and there are no signs of
leukemia, a third phase of treatment called consolidation or intensification
therapy, is given. Consolidation therapy uses high-dose chemotherapy to
attempt to kill any remaining leukemia cells.
The fourth phase of treatment, called maintenance therapy,
uses chemotherapy for several years to maintain the remission.
Treatment by prognostic group
Treatment for childhood acute lymphoblastic leukemia depends on the
prognostic group to which your child is assigned based primarily on your child's
age and white blood cell count at diagnosis.
Your child may receive treatment that is considered standard based on its
effectiveness in a number of patients in past studies, or you may choose to have
your child take part in a clinical trial. Not all patients are cured with
standard therapy and some standard treatments may have more side effects than
are desired. For these reasons, clinical trials are designed to test new
treatments and to find better ways to treat cancer patients. Clinical trials are
ongoing in most parts of the country for most stages of childhood ALL. For more
information, call the Cancer Information Service at 1-800-4-CANCER
(1-800-422-6237); TTY at 1-800-332-8615.
Untreated Childhood Acute Lymphoblastic Leukemia
Your child's treatment will probably be remission induction chemotherapy to
kill cancer cells and cause the leukemia to go into remission. Induction
chemotherapy is almost always successful in inducing remission. Intrathecal
and/or high-dose systemic chemotherapy, with or without radiation therapy to the
brain, may also be given to prevent the spread of cancer cells to the brain and
spinal cord. Clinical trials are testing new ways of inducing remission.
Childhood Acute Lymphoblastic Leukemia in Remission
Your child's treatment will probably be intensive chemotherapy to kill any
remaining cancer cells. Intrathecal and/or high doses of systemic chemotherapy,
with or without radiation therapy to the brain, may also be given during this
phase of treatment to prevent the spread of cancer cells to the brain and spinal
cord. Following intensification therapy, chemotherapy generally continues until
the child has been in continuous remission for several years.
Recurrent Childhood Acute Lymphoblastic Leukemia
Treatment depends on the type of treatment your child received before, how
soon the cancer came back following treatment, and whether the leukemia cells
are found outside the bone marrow. Your child's treatment will probably be
systemic or intrathecal chemotherapy, radiation therapy, or bone marrow
transplantation. You may want to consider entering your child into a clinical
trial of new chemotherapy drugs or bone marrow transplantation.
Source: National Institutes of Health; National Cancer Institute
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