The most common type of childhood leukemia, Childhood Acute Lymphoblastic Leukemia, or A.L.L., is a cancer of the white blood cells.
To better understand this disease, let’s break it down and examine what certain parts of the body are supposed to do, and how they work when a person has A.L.L.
This is the soft, spongy insides of certain bones. In infants, almost all the bones of the body contain active bone marrow. As a person matures, usually by their teenage years, the red marrow is mainly found in the flat bones like the skull, shoulder blades, ribs and hip bones, and in the vertebrae – the bones in the spine.
Bone marrow is made up of hematopoietic blood stem cells and fat cells which help in creating new blood cells. There are two kinds of bone marrow, red and yellow. The hematopoietic blood stem cells are found in the red marrow. These cells go through a process of changes to make new blood cells, during which they can turn into one of three types: red blood cells, white blood cells, or platelets.
Red blood cells
When a person inhales oxygen into the lungs, it is the job of the red blood cells carry it to the rest of the tissues and organs in the body. They also take carbon dioxide back to the lungs to be removed through exhaling.
Ever have a small cut that bleeds for a moment and then stops? That means your platelets are hard at work. These little cell fragments plug holes in blood vessels to stop bleeding. When a person has a low platelet count, it can cause them to bleed and bruise easily.
White blood cells
Mature white blood cells help the body fight infections. Too few white blood cells in the body will weaken the immune system and make a person more susceptible to bacteria, virus and other infectious germs.
There are three types of white blood cells: lymphocytes, monocytes and graulocytes. For the purpose of understanding A.L.L., we’ll only focus on the first one.
Lymphoblasts are immature white blood cells that develop into lymphocytes. There are two main types:
- B lymphocytes (B cells) – help protect against germs such as bacteria and viruses by making proteins called antibodies. These antibodies attach themselves to germs which then mark it for destruction by other parts of the immune system.
- T lymphocytes (T cells) – some types of T cells destroy germs directly, while others help by boosting or slowing the activity of other immune system cells.
Any of the hematopoietic blood stem cells can turn into a leukemia cell and once this happens, those cells no longer develop or mature in a normal way. In the case of A.L.L, the lymphocytes (white blood cells) are the ones affected. The cancer stops the lymphoblastic cells from maturing into a fully developed lymphocytes. It can start in either early B cells or T cells, though B-cell leukemia tends to be more common.
The leukemia cells then reproduce and build up in the bone marrow, crowding out the normal cells. It can spread quickly from there and move into the blood stream and then to other organs and tissues. With so many of the leukemia cells being produced, they hinder the mature cells from performing their functions – like fighting off infections and transporting hemoglobin to other parts of the body.
Tests to diagnose childhood A.L.L.
There are several tests which are used to diagnose a patient with childhood A.L.L. They are listed below with explanations and descriptions of the actual procedures.
- Physical exam and history – A doctor will check the patient’s body looking for signs of disease, like lumps, bruising, swollen lymph nodes, and signs of bleeding such as petechia (red or purplish flat spots caused by bleeding into the skin).
- Complete blood count (CBC) with differential – Blood is collected and samples are sent to the laboratory where they count the number of red blood cells and platelets, the number and the type of white blood cells, how much hemoglobin is in the red blood cells, and how much of the sample is made up of red blood cells.
- Bone marrow aspiration and biopsy – After a small area of skin has been numbed, a long, hollow needle is inserted into the hip bone or breastbone. Samples of bone marrow, bone, and blood are then removed for examination by a pathologist.
- Blood chemistry studies: A procedure in which a blood sample is checked to measure the amounts of certain substances released into the blood by organs and tissues in the body. An unusual (higher or lower than normal) amount of a substance can be a sign of disease in the organ or tissue that makes it.
- Chest x-ray – An x-ray of the organs and bones inside the chest is taken to look for masses or tumors.
Once a diagnosis of childhood A.L.L. has been given, more tests are done to find out if and/or how far the cancer has spread throughout the body. These tests are:
- Lumbar puncture – This procedure is also known as a spinal tap or LP. A needled is inserted into the spinal column and a sample of cerebrospinal fluid is collected. It is then checked for the presence of leukemia cells.
- Chest x-ray – An x-ray of the organs and bones inside the chest is taken to look for masses or tumors.
- Testicular biopsy – This procedure is done only if the doctors found anything unusual about the testicles during the physical exam. A sample of cells or tissues from the testicles is collected for the pathologist to view under the microscope.
The results of these tests will determine what “stage” the cancer has reached. The further the spread or extent, the higher the stage. However, when dealing with A.L.L., risk groups are used instead of stages. Once the risk group has been determined, the medical team can begin developing and implementing the treatment plan best suited for the patient.
The main goal is to get the patient into remission. The first step towards that goal is to get the patient’s blood counts back to normal. Treatments are done in three phases for Childhood A.L.L. Those are:
- Induction therapy: This is the first phase of treatment. Its purpose is to kill the leukemia cells in the blood and bone marrow. This puts the leukemia into remission. This is also called the remission induction phase.
- Consolidation /intensification therapy: This is the second phase of therapy. It begins once the leukemia is in remission. The purpose of consolidation/intensification therapy is to kill any remaining leukemia cells that may not be active but could begin to regrow and cause a relapse.
- Maintenance therapy: This is the third phase of treatment. Its purpose is to kill any remaining leukemia cells that may regrow and cause a relapse. Often the cancer treatments are given in lower doses than those used for induction and consolidation/intensification therapy. This is also called the continuation therapy phase.
Bone marrow biopsy and aspirates are done throughout all phases to see how well the leukemia is responding to treatment.
There are four types of standard treatments used:
- Chemotherapy is the first treatment tried with the goal of achieving complete remission. This treatment uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. When chemotherapy is taken by mouth or injected into a vein or muscle, the drugs enter the bloodstream and can reach cancer cells throughout the body (systemic chemotherapy). When chemotherapy is placed directly into the cerebrospinal fluid (intrathecal), an organ, or a body cavity such as the abdomen, the drugs mainly affect cancer cells in those areas (regional chemotherapy). Combination chemotherapy is treatment using more than one anticancer drug. The way the chemotherapy is given depends on the type of the cancer being treated.Intrathecal chemotherapy or high doses of chemotherapy injected into a vein may be used to treat childhood ALL that has spread, or may spread, to the brain and spinal cord. When used to prevent cancer from spreading to the brain and spinal cord, it is called central nervous system (CNS) sanctuary therapy or CNS prophylaxis. CNS sanctuary therapy is given in addition to chemotherapy by mouth or vein that is intended to kill leukemia cells in the rest of the body. All children with ALL receive CNS sanctuary therapy as part of their treatment.
Because most anticancer drugs given by mouth or injected into a vein to kill leukemia cells may not reach leukemia cells in the CNS (brain and spinal cord), the leukemia cells are able to find “sanctuary” or hide in the CNS. Certain anticancer drugs, intrathecal chemotherapy, and radiation therapy to the brain are able to reach leukemia cells in the CNS and are given to kill the leukemia cells and prevent the cancer from recurring (coming back). CNS sanctuary therapy is also called CNS prophylaxis because it is given to stop leukemia cells from growing in the CNS.
- Radiation therapy is a treatment that uses high-energy x-rays or other types of radiation to kill cancer cells or keep them from growing. There are two types of radiation therapy. External radiation therapy uses a machine outside the body to send radiation toward the cancer. Internal radiation therapy uses a radioactive substance sealed in needles, seeds, wires, or catheters that are placed directly into or near the cancer. External radiation therapy may be used to treat childhood ALL that has spread, or may spread, to the brain and spinal cord. When used this way, it is called central nervous system (CNS) sanctuary therapy or CNS prophylaxis.Because radiation therapy to the brain can affect growth and brain development in young children, many children with ALL are treated without radiation therapy. Radiation therapy to the brain and spinal cord is sometimes used as CNS sanctuary therapy to treat children and teenagers in the high risk group. Clinical trials are studying new ways of using radiation therapy that may have fewer side effects, including giving lower doses of radiation.
- Chemotherapy with stem cell transplant is a method of giving very high doses of chemotherapy and sometimes radiation therapy, and then replacing the blood-forming cells destroyed by the cancer treatment. Stem cells (immature blood cells) are removed from the blood or bone marrow of a donor. After the patient receives very high doses of chemotherapy and sometimes radiation therapy, the donor’s stem cells are given back to the patient through an infusion. These reinfused stem cells grow into (and restore) the patient’s blood cells. A stem cell transplant may use stem cells from a donor who is or is not related to the patient.Stem cell transplant is rarely used as initial treatment for children and teenagers with ALL. It is used more often as part of treatment for ALL that relapses (comes back after treatment).
- Targeted therapy uses medicines or other treatments that target and attack specific cancer cells without harming normal cells.
Reaching initial complete remission DOES NOT mean the patient is cured.
After achievement of initial complete remission, more treatment is needed to be cured. This treatment can include more chemotherapy or radiation to the brain. Stem cell or bone marrow transplant from another person may also be done. Further treatment depends on various factors including the age and health of the patient, genetic changes in the leukemia cells, how many courses of chemo it took to achieve remission, if abnormal cells are still detected under the microscope, and availability of donors for stem cell transplant.
Patients are considered cured after 10 years in remission. This means that the patient must not have any signs or trace of leukemia cells in their system for 10 years after remission has been reached.
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*DISCLAIMER: Information provided on this page has been pulled from various medical and cancer websites. It is in no way to be considered or intended as medical advice of any kind. A cancer patient will have a team of doctors and medical professionals to help create a plan of treatment. If you are seeking advice or treatment for yourself or your child, please see your medical professionals. This page may or may not contain the most recent or up-to-date information, though attempts will be made to keep it updated.