What Is Acute Lymphocytic Leukemia (ALL)?
Overview
Acute (sudden onset) lymphocytic leukemia (ALL) is also known as lymphoblastic or lymphoid leukemia. It is the most common type of leukemia in children.
Lymphocytes are a type of white blood cell that help fight infection. They are formed in the center cavity of certain bones, in a sponge-like tissue called marrow.
In ALL, the bone marrow makes too many immature, abnormal lymphocytes. These immature, abnormal lymphocyte cancer cells are called lymphoblasts. Lymphoblasts do not fight infection well. They also crowd out other kinds of blood cells forming in the bone marrow, causing shortages. Because of this, there may not be enough oxygen-carrying red blood cells. There may also not be enough platelets, which help blood clot when needed.
Signs and symptoms of Acute Lymphocytic Leukemia usually develop over a period of days to weeks. Signs and symptoms are similar to those of other leukemias: fatigue, fevers, bone pain, persistent infections, pale skin color, abdominal pain, loss of appetite, and excessive bruising and / or frequent nosebleeds.
Incidence
ALL accounts for about 75-80% of childhood leukemias.
Causes
Most ALL cancer cells contain abnormal genes. What has caused the cells’ genetic code to be changed is often not known.
Risk Groups
Many types of cancer are grouped in Stages based on how far the cancer has spread when found. Because ALL is a cancer of the blood, it has already spread throughout the body at the time of diagnosis. So, instead of Stages, specialists assign leukemia patients to "risk groups” based on well-defined criteria.
Risk groups help the medical team decide on the best course of treatment. For example, children with high-risk ALL will receive more medications than children with standard-risk ALL. The doctor (oncologist) will look at several facts to tell which risk group a child belongs to. One fact is the child’s age at diagnosis. Another fact is how many white blood cells are found in a sample of blood at diagnosis.
Initially, patients are grouped as follows:
- Standard (low) risk: Children aged 1 to 9 years who have a white blood cell count under 50,000 at diagnosis.
- High risk: Children younger than 1 year or older than 9 years, and any child with a white blood cell count of 50,000 or more at diagnosis.
Additionally, the doctor (oncologist) will also consider:
- Whether B or T lymphocytes formed the leukemia cells. There are various kinds of lymphocytes, and it is important to know which kind started the cancer.
- The type of changes found in the leukemic cell genes
- Whether the cancer has spread to the brain and spinal cord, testicles or other parts of the body
- How quickly the leukemia responds to therapy
Typical Treatment
Oncologists look at the characteristics of each patient’s leukemia and then recommend the treatment that is best for each patient. Treatment is usually started immediately and often includes these phases:
Induction phase:
Treatment begins with one month of intense chemotherapy. All or nearly all of this therapy will be given in the hospital. Strong medicine is given through a vein and by mouth. Treatments will also include medicine given in the spine through a spinal tap. This step is to kill any cancer cells in the brain or spinal cord. The Induction phase causes remission in about 95% of patients. Remission means the leukemia is no longer detectable by testing. However, we know that leukemia cells are still present in the body.
Consolidation / Interim Maintenance / Intensification phases:
Over the next seven to eight months, more anti-leukemia medications are given. Some medications are given in the hospital, and some are given in an outpatient clinic. The goal is to get rid of any leukemia cells that may still be hidden.
Some children will benefit from just additional chemotherapy while other children will need additional chemotherapy plus immune-based therapy. In this type of therapy, special antibodies are given to help the body’s immune system target the cancer cells. Treatment is individualized to each child’s type of leukemia.
Maintenance phase:
In this phase, chemotherapy is continued but is given in the outpatient clinic. Also, during Maintenance, the child is required to take chemotherapy by mouth at home. Maintenance usually lasts about 18 months. Overall time for leukemia treatment from start to finish is about 2.5 years.
Relapsed and Refractory Acute Lymphoblastic Leukemia
Sometimes leukemia does not go away in the first few months of treatment. This is called “refractory” ALL.
Leukemia may come back after a time of remission. This is called “relapsed” ALL.
In either case, a new treatment plan will be developed.
The new treatment plan may include:
- A more intense and / or longer course of chemotherapy
- Different chemotherapy medicines
- A stem cell transplant
- Immunotherapy
Immunotherapy is a huge breakthrough in the treatment of refractory and relapsed ALL. Immunotherapy uses the body’s immune system to help find and kill cancer cells. One example is chimeric antigen receptor (CAR T-cell) therapy. CAR T-cell therapy changes a type of immune cell called T cells to find and attack the cancer hiding in the body. It may provide long-term remission. It may be a cure for patients with B-cell acute lymphoblastic leukemia (B-ALL).
Immunotherapies can be used alone or in combination with other cancer treatments. Only a small number of children’s hospitals, including Cincinnati Children’s, offer immunotherapy for ALL.
Lifelong Follow-Up
Survivors of childhood cancer may have chemotherapy-related health problems later in life. Therefore, there are long-term survivorship programs to serve the needs of this unique population. For more information, see Cincinnati Children’s Cancer Survivorship Program.
Outlook
The overall outlook for children and young adults with ALL is good and has improved substantially over the past 20 years. According to the National Cancer Institute, over 95% of children treated for ALL achieve remission after the Induction phase (one month). With today's treatment, in about 85% of these cases, the cancer does not return. The treating oncologist is an expert resource for more information.
