Acute lymphoblastic leukemia is an acute form of leukemia, or cancer of the white blood cells, characterized by the overproduction and accumulation of cancerous, immature white blood cells, known as lymphoblasts. In persons with ALL, lymphoblasts are overproduced in the bone marrow and continuously multiply, causing damage and death by inhibiting the production of normal cells (such as red and white blood cells and platelets) in the bone marrow and by spreading (infiltrating) to other organs. ALL is most common in childhood, with a peak incidence at 2–5 years of age and another peak in old age.
About 6,000 cases are reported in the United States every year. Internationally, ALL is more common in Caucasians than in Africa; it is more common in Hispanics and in Latin America. Cure is a realistic goal and is achieved in more than 80% of affected children, although only 20-40% of adults are cured. "Acute" refers to the relatively short time course of the disease, distinguishing it from chronic lymphocytic leukemia, which has a potential time course of many years.
Signs and symptoms of acute lymphocytic leukemia may include:
- Bleeding from the gums
- Bone pain
- Frequent infections
- Frequent or severe nosebleeds
- Lumps caused by swollen lymph nodes in and around the neck, underarm, abdomen or groin
- Pale skin
- Shortness of breath
- Weakness, fatigue or a general decrease in energy
Acute lymphocytic leukemia occurs when a bone marrow cell develops errors in its DNA. The errors tell the cell to continue growing and dividing, when a healthy cell would normally stop dividing and eventually die. When this happens, blood cell production becomes abnormal. The bone marrow produces immature cells that develop into leukemic white blood cells called lymphoblasts. These abnormal cells are unable to function properly, and they can build up and crowd out healthy cells.
It's not clear what causes the DNA mutations that can lead to acute lymphocytic leukemia. But doctors have found that most cases of acute lymphocytic leukemia aren't inherited.
Many types of cancer can be prevented by lifestyle changes to avoid certain risk factors, but there is no known way to prevent most cases of leukemia at this time.
Factors that may increase the risk of acute lymphocytic leukemia include:
- Previous cancer treatment. Children and adults who've had certain types of chemotherapy and radiation therapy for other kinds of cancer may have an increased risk of developing acute lymphocytic leukemia.
- Exposure to radiation. People exposed to very high levels of radiation, such as survivors of a nuclear reactor accident, have an increased risk of developing acute lymphocytic leukemia.
- Genetic disorders. Certain genetic disorders, such as Down syndrome, are associated with an increased risk of acute lymphocytic leukemia.
- Having a brother or sister with ALL. People who have a sibling, including a twin, with acute lymphocytic leukemia have an increased risk of ALL.
Tests and procedures used to diagnose acute lymphocytic leukemia include:
- Blood tests. A blood test may reveal too many white blood cells, not enough red blood cells and not enough platelets. A blood test may also show the presence of blast cells — immature cells normally found in the bone marrow but not circulating in the blood.
- Bone marrow test. During bone marrow aspiration, a needle is used to remove a sample of bone marrow from the hipbone. The sample is sent to a lab for testing to look for leukemia cells. Doctors in the lab will classify blood cells into specific types based on their size, shape and other features. They also look for certain changes in the cancer cells and determine whether the leukemia cells began from the B lymphocytes or T lymphocytes. This information helps your doctor develop a treatment plan.
- Imaging tests. Imaging tests such as X-ray, computerized tomography (CT) scan or ultrasound scan may help determine whether cancer has spread to the brain and spinal cord or other parts of the body.
- Spinal fluid test. A lumbar puncture test, also called a spinal tap, may be used to collect a sample of spinal fluid — the fluid that surrounds the brain and spinal cord. The sample is tested to see whether cancer cells have spread to the spinal fluid.
Based on these tests, doctors may categorize ALL into one of the following types:
- Early pre-B ALL
- Common ALL
- Pre-B-cell ALL
- Mature B-cell ALL (Burkitt leukemia)
- Pre-T-cell ALL
- Mature T-cell ALL
Before treatment was available, most people who had ALL died within 4 months of the diagnosis. Nowadays, nearly 80% of children and 30 to 40% of adults with ALL are cured. For most people, the first course of chemotherapy brings the disease under control (complete remission). Children between the ages of 3 and 7 have the best prognosis. Children younger than 2 and older adults fare least well. The white blood cell count and particular chromosome abnormalities in the leukemia cells also influence outcome.
In general, treatment for acute lymphocytic leukemia falls into separate phases:
- Induction therapy. The purpose of the first phase of treatment is to kill most of the leukemia cells in the blood and bone marrow and to restore normal blood cell production.
- Consolidation therapy. Also called post-remission therapy, this phase of treatment is aimed at destroying any remaining leukemia in the body, such as in the brain or spinal cord.
- Maintenance therapy. The third phase of treatment prevents leukemia cells from regrowing. The treatments used in this stage are often given at much lower doses over a long period of time, often years.
- Preventive treatment to the spinal cord. People with acute lymphocytic leukemia may also receive treatment to kill leukemia cells located in the central nervous system during each phase of therapy. In this type of treatment, chemotherapy drugs are often injected directly into the fluid that covers the spinal cord.
Depending on your situation, the phases of treatment for acute lymphocytic leukemia can span two to three years.
Treatments may include:
- Chemotherapy. Chemotherapy, which uses drugs to kill cancer cells, is typically used as an induction therapy for children and adults with acute lymphocytic leukemia. Chemotherapy drugs can also be used in the consolidation and maintenance phases.
- Targeted drug therapy.
Targeted drugs attack specific abnormalities present in cancer cells that help them grow and thrive. A certain abnormality called the Philadelphia chromosome is found in some people with acute lymphocytic leukemia. For these people, targeted drugs may be used to attack cells that contain that abnormality. Targeted drugs include imatinib (Gleevec), dasatinib (Sprycel) and nilotinib (Tasigna), ponatinin (Iclusig). These drugs are approved for patients with the Philadelphia chromosome-positive form of ALL that is resistant or intolerant to prior tyrosine kinase inhibitor therapy. Whereas, blinatumomad (Blincyto) is approved for Treatment of Philadelphia chromosome-negative relapsed or refractory B-cell precursor acute lymphoblastic leukemia.
- Radiation therapy. Radiation therapy uses high-powered beams, such as X-rays, to kill cancer cells. If the cancer cells have spread to the central nervous system, your doctor may recommend radiation therapy.
- Stem cell transplant. A stem cell transplant may be used as consolidation therapy in people at high risk of relapse or for treating relapse when it occurs. This procedure allows someone with leukemia to re-establish healthy stem cells by replacing leukemic bone marrow with leukemia-free marrow from a healthy person.
Refer to Research Publications.