Acute Lymphoblastic Leukemia
What is acute lymphoblastic leukemia (ALL)?
Acute lymphoblastic leukemia (ALL) is a cancer that involves the white blood cells of the bone marrow. The condition develops in the bone marrow where blood cells are produced. The bone marrow produces three kinds of blood cells: red blood cells, white blood cells and platelets. The malignant cell in ALL is a lymphocyte, which is a type of white blood cell.
In ALL, the lymphocytes somehow escape the normal controls that direct the way they mature. Instead of aging in a way that allows them to do their part in helping to fight infection, they remain young, continue to multiply and are not effective in fighting infection. These immature lymphocytes are called lymphoblasts, blasts or leukemic cells. There are many kinds of lymphocytes, including B cell and T cell lymphocytes. Leukemia can occur in any type of lymphocyte; the most common type of ALL is early or pre-B cell leukemia.
Acute lymphoblastic leukemia is the most common leukemia diagnosed in children. Most children are diagnosed between the ages of two and eight, and it is more prevalent in boys than girls. The cause of ALL is not known, but it is not hereditary nor is it contagious. Nothing done or not done by the child, parent or family has caused the cancer in your child. Possible factors that are currently under study include the environment and genetics.
What are symptoms of ALL?
As the leukemic blast cells accumulate in the bone marrow, they begin to crowd out the normal cells that develop there. Eventually, they occupy so much of the space that red blood cells, platelets, and normal white blood cells cannot be produced. When this happens, a child develops symptoms indicating that normal, mature blood cells are not being manufactured in adequate numbers.
When red blood cells are crowded out, a child's hemoglobin levels will drop. The child may look pale and feel tired and irritable. When platelets are low, the child may bruise more easily and have bleeding problems such as bleeding gums or nose bleeds. When normal, mature white blood cells are crowded out, no cells remain to fight bacteria, and infections may occur. The accumulation of blasts in the bone marrow can also cause increased pressure and result in bone pain.
The leukemic cells can "spill out" from the bone marrow and travel anywhere in the body that blood goes. They can spread or travel to the lymph nodes, spleen and liver, which may cause these organs to become enlarged. Leukemia cells can also spread into the spinal fluid that surrounds the spinal cord and brain.
How is ALL diagnosed?
A doctor takes a history of your child's symptoms, performs a physical examination, and completes a microscopic examination of your child's blood cells, bone marrow cells, and spinal fluid.
Because leukemia starts in the bone marrow, patients undergo a bone marrow aspiration/biopsy to confirm the diagnosis. During this procedure, the physician inserts a needle into the hipbone and removes some marrow cells to test under the microscope. A lumbar puncture (LP) or spinal tap is when a needle is inserted into the spinal canal and spinal fluid is removed and tested for leukemia cells. These tests are often done under sedation or general anesthesia.
How is ALL treated?
The treatment for ALL is the administration of chemotherapy and generally consists of five or more phases: induction, consolidation, interim maintenance, delayed intensification, and maintenance. Radiation therapy to the head is used if leukemic cells have spread to the spinal fluid and in certain high-risk types of ALL.
The goal in induction therapy is to achieve a complete remission or disappearance of all leukemic cells. During induction, your child receives medications to kill as many leukemia cells as possible. Bone marrow tests are done to determine when a remission is achieved. Induction therapy usually lasts about four weeks. The length of your child's hospital stay will depend on the type of treatment he or she receives and whether or not any complications occur.
The next phase is consolidation. The goal is to solidify remission through use of chemotherapy drugs. During this phase, chemotherapy is frequently given into the spinal fluid during spinal tap procedures as well as into the vein. This destroys any leukemia cells that can hide in the spinal fluid. Chemotherapy given into the bloodstream does not cross well into the spinal fluid therefore chemotherapy must be given directly into it.
Leukemia cells can escape the medicines given in induction by hiding in the fluid that bathes the spinal cord and brain. This is possible because of a mechanism called "the blood-brain barrier" which stops passage of materials from the blood into the brain and spinal cord. Central nervous system prophylaxis (prevention) therapy is necessary to destroy any leukemic cells hidden in the cerebral spinal fluid. During this phase, your child will receive frequent spinal taps so medications can be given directly into the cerebral spinal fluid. This phase lasts about four weeks, and is usually given on an outpatient basis. If your child requires radiation therapy, it is usually done during consolidation.
Interim maintenance is a phase designed to give a break of less intense therapies between each course of delayed intensification. This phase is usually two months long and consists mostly of medications given by mouth at home. The phase of interim maintenance followed by delayed intensification is repeated.
The goal of the next phase, delayed intensification, is to give intense chemotherapy when the amount of leukemia cells is very low in order to destroy this small, undetectable number of cells. This medication is given as an outpatient, however patients may need to be hospitalized for some side effects such as low blood counts and fever. Delayed intensification lasts approximately eight weeks.
Maintenance therapy is aimed at keeping your child in remission and destroying any leukemia cells that may remain in your child's body. During this phase your child receives medication in the clinic once every three to four weeks and takes oral medication at home. Spinal taps are necessary about every three months. Maintenance therapy continues for about two to three years. During maintenance, children's hair grows back and school age children can return to school on a regular basis. Once your child has completed maintenance therapy, blood tests are done periodically to monitor your child's response to treatment.
About treatment for acute lymphoblastic leukemia at Children's
Children's cancer and blood disorders program consistently achieves treatment results ranking it as one of the top ten programs in the U.S. Children's treats the majority of children with cancer and blood disorders in Minnesota and provides patients with access to a variety of clinical trials of ground-breaking new treatments. Through our renowned leukemia/lymphoma program, patients experience unparalleled family support, a nationally renowned pain management team, and compassionate, coordinated care.
If you are a family member looking for a Children's hematologist or oncologist or wanting to schedule an appointment, please call our clinic at Children's – Minneapolis at (612) 813-5940.
If you are a health professional looking for consultation or referral information, please call Children's Physician Access at 1-866-755-2121 (toll-free) and ask for the on-call hematologist/oncologist.