Treatment of Acute Leukemia in Children
Treatment of childhood leukemia differs slightly between ALL and AML, but the treatment for both will include chemotherapy to kill the abnormal cells (blasts) in the blood and bone marrow.
Chemotherapy
Chemotherapy is the use of certain drugs to target and destroy rapidly growing cancer cells. Doctors usually give a combination of different chemotherapy drugs to treat leukemia in the induction phase. In the consolidation phase, the patient may receive a different combination of chemotherapy drugs or high doses of chemotherapy combined with stem-cell transplantation. The doctor may also recommend CNS prophylaxis therapy using intrathecal chemotherapy (chemotherapy injected in the spinal fluid). The doctor will inject chemotherapy drugs into the fluid chamber that surrounds the brain and spinal cord in order to prevent the cancer from reaching or spreading to the nervous system. This is very important for the child to receive even if the CNS is negative for leukemia. During maintenance, the patient may receive some drugs by injection and others by mouth.
Phases of Treatment
Treatment of childhood leukemia is usually divided into three phases: induction, consolidation and maintenance. The total duration of these three phases is usually about two years for ALL. It is important to start treatment as soon as possible after diagnosis because childhood leukemia progresses very rapidly.
- Induction – Induction is the first and most intensive phase of treatment for childhood leukemia. The doctor uses chemotherapy to destroy the blast cells in the patient's blood and reduce the number of blasts to a nearly undetectable level. The goal of induction is to put the cancer into remission. In the past, remission meant that no leukemia cells were detected in the bone marrow by a microscope and blood counts were normal; however, there still could be some leukemia cells in the body. New methods of detecting leukemia cells are changing the definition of remission.
- Consolidation – Consolidation is the second phase of treatment for childhood leukemia. After the cancer is put into remission, the doctor will try to kill any small amount of cancer cells left in the body that may eventually cause a relapse.
- Maintenance – Maintenance is the third phase of treatment for childhood leukemia. The maintenance phase consists of lower doses of chemotherapy given for longer periods of time to ensure that there are no leukemia cells left in the blood. In maintenance they can go to school and have a normal life. Only 1 subtype of AML (acute promyelocytic leukemia (APL)) requires maintenance chemotherapy.
The doctor may recommend CNS sanctuary therapy throughout the phases of treatment to kill any remaining cancer cells in the brain, spinal cord or spinal fluid. The central nervous system is called a sanctuary site because certain chemotherapies have a hard time reaching it.
The doctor may also recommend some of the following therapies to treat childhood leukemia:
Radiation Therapy
Radiation therapy uses waves of high-energy rays to target and kill cancer cells. Radiation therapy is not commonly used as a primary treatment for childhood leukemia. Radiation is used to treat central nervous system leukemia by directing radiation to the brain and sometimes the spinal cord. The doctor may also recommend undergoing radiation treatment to the entire body as part of a stem-cell transplantation.
Stem-cell transplantation
The patient's bone marrow is first destroyed using high doses of chemotherapy with or without total body radiation. These high doses destroy regular cells in the blood and bone marrow, as well as cancer cells. After chemotherapy and radiation, the patient receives blood-forming stem cells from a donor that help the body form new, healthy blood cells.
Targeted Therapy
In some cases of ALL and AML, chromosome or gene changes may cause bone marrow to produce too much tyrosine kinase, an enzyme that fuels cancer cell growth. Tyrosine kinase inhibitors are a form of targeted therapy that prevent this process from occurring. Other chromosome changes can cause changes in a receptor on leukemia cells. Targeted therapy is one of the main treatments for certain sub-types of ALL and AML. It is most often used for ALL and is given along with the leukemia treatment.
CAR-T Immunotherapy
One approach to immunotherapy currently being studied in clinical trials involves engineering a patient’s own immune cells to recognize and attack tumor cells. T-cells are a type of immune cell collected from the patient’s own blood. After collection, the T-cells are genetically engineered to produce special receptors on their surface called chimeric antigen receptors (CARs). These genetically engineered cells are then re-infused into the patient’s bloodstream. After re-infusion, the T-cells multiply in the patient’s body and with guidance from their engineered receptor, and are able to recognize and kill cancer cells. Currently CAR-T Immunotherapy is only used for B cell ALL (Acute Lymphoblastic Leukemia).
Leukapheresis
If the white blood cell count is very high, the blood flow may not reach all the tissues. The doctor may recommend this procedure to reduce the amount of leukemia cells in the blood before chemotherapy has a chance to start working. The doctor will pass the patient's blood through a machine that separates white blood cells, including leukemia cells, from other blood cells. After removal of the white blood cells, the remaining blood cells and plasma are returned to the body. This is a short-term solution that temporarily reduces the amount of leukemia in the blood while the chemotherapy takes effect. Lowering the white blood cell count may reduce symptoms and the risk of complications.
Clinical Trials
Clinical trials allow patients to try a new treatment before it is available to the general public. In some cases, this may be a new drug that has not been used in humans before, or it may be a drug or drug combination that is not currently used for that specific type of cancer. Early phase clinical trials are often used to test side effects of a drug or drug combination, while later phase clinical trials are used to see how effective a new treatment might be for a certain type of cancer. Clinical trials allow doctors and researchers to improve the treatment of cancers with possibly more effective therapies. A clinical trial may be a new, groundbreaking drug or it may have no direct benefit to the patient. It is important to talk with your doctor about the pros and cons of clinical trials for your situation.
