Acute lymphoblastic leukemia (ALL), also called acute lymphocytic leukemia, is the most common form of cancer found in children. ALL is a blood cancer that develops from lymphocytes — white blood cells that are part of the body’s immune system. Lymphocytes include B cells, T cells, and natural killer cells. When ALL develops from B cells, it is called B-cell acute lymphoblastic leukemia.
Nearly 6,000 people are diagnosed with ALL each year. Only half of a percent of all cancers in the United States are ALL. About 75 percent of acute lymphoblastic leukemia cases are the B-cell type, and the rest are T-cell type. Children under the age of 5 years and older adults have a higher risk of developing B-cell ALL. Additionally, white people are more likely to be diagnosed with ALL than Black people.
ALL and other types of leukemia develop from cells in the bone marrow. The bone marrow contains stem cells that make all of the different types of cells in the blood. Sometimes, the DNA in one of the bone marrow cells changes. Gene changes can make blood cells grow out of control, leading to leukemia.
In the case of B-cell ALL, gene changes cause immature B cells to grow too quickly. These cells take over the bone marrow and then spill over into the blood. They can also collect in tissues like the spleen, thymus, and central nervous system (brain and spinal cord).
Doctors don’t know for sure what causes any one case of ALL. It’s usually not clear what causes gene mutations (changes). However, researchers have identified certain risk factors that can increase a person’s chances of having gene changes that lead to B-cell ALL.
Certain genetic disorders can lead to a greater ALL risk, such as:
Environmental factors also play a role in ALL risk. High levels of radiation can sometimes cause ALL many years later. Additionally, people with Epstein-Barr virus infections may be more likely to develop certain kinds of B-cell ALL.
There are many different subtypes of B-cell ALL. Usually, B-cell ALL is divided into groups based on which gene changes are present within the leukemia cells. In many cases, leukemia cells have changes in their chromosomes (long pieces of DNA that contain genes). Normal cells have 46 chromosomes, but leukemia cells may have too few or too many. Alternatively, the chromosomes may have a translocation, in which a part of one or more than one chromosome breaks off, duplicates, or attaches to a different chromosome.
The World Health Organization (WHO) has come up with a system that classifies B-cell ALL based on gene changes. One of the most common gene changes is a translocation between chromosome 9 and chromosome 22, which results in a change called the Philadelphia chromosome. This translocation is also called CML — chronic myelogenous leukemia. When CML cells transform into acute leukemia, sometimes it transforms into ALL. About 20 percent to 30 percent of people with ALL have the Philadelphia chromosome, which leads to an abnormal gene that makes cells multiply very quickly.
Other types of B-cell acute lymphoblastic leukemia are:
Most B-cell ALL subtypes develop from immature cells that make B cells. However, another subtype of B-cell ALL affects more fully developed cells similar to Burkitt lymphoma.
Your exact subtype of ALL helps your doctor determine which treatments will likely be most effective.
When leukemia cells grow out of control, they crowd out the healthy blood cells in the bone marrow and blood, making it harder for the normal cells to do their jobs. People with B-cell ALL often have anemia (low levels of red blood cells), thrombocytopenia (low levels of platelets), and leukopenia (low levels of white blood cells). Low numbers of healthy blood cells cause many of the symptoms of ALL.
People with B-cell ALL may experience:
Many other common health problems also cause the same symptoms. Experiencing these issues does not mean that you have B-cell ALL. However, if you notice any of these signs, talk to your doctor.
A diagnosis of acute lymphoblastic leukemia can be made with a few different tests, which include:
Figuring out what type of leukemia you have is an important part of the diagnosis. It helps doctors make treatment decisions and predict prognosis (disease outlook). To figure out the subtype, a doctor may send samples of blood or bone marrow to a laboratory for testing. There are several possible lab tests, including:
Once your doctor has diagnosed ALL and has determined which gene changes you have, they can recommend treatments and estimate your outlook.
The right treatment for one person with ALL may not be a good fit for the next person. Many factors go into your treatment plan, including your age, your overall health, and how advanced your leukemia is. You may also need different treatments if your ALL is refractory (resistant to treatment) or relapsed (came back after treatment).
ALL is often treated in different phases:
You may receive different treatments or take medications at different dosages during each treatment phase.
Chemotherapy drugs kill cancer cells by blocking them from growing. You may receive chemotherapy in the form of a pill, injection, or intravenous (IV) tube (a method that delivers fluids directly into a vein). Doctors may also deliver chemotherapy drugs to the central nervous system to kill any leukemia that has spread there.
Chemotherapies used to treat ALL include:
Targeted therapy drugs attack specific molecules found on cancer cells. One targeted therapy used to treat B-cell ALL is Rituxan (rituximab). This drug blocks a protein called CD20 that is found on B cells. Additionally, Blincyto (blinatumomab) and Besponsa (inotuzumab ozogamicin) are targeted therapy medications that can be used to treat refractory or relapsed B-cell ALL.
Other targeted therapies are used to treat people who have Philadelphia chromosome-positive ALL. These therapies include:
Some people with ALL can be treated with a stem cell transplant — a procedure where you are treated with a high dose of chemotherapy and then given stem cells from a donor. The chemotherapy kills both cancer cells and normal cells, and then the stem cells can make new, healthy blood cells.
Additional treatment options may include:
Many cancer treatments cause unpleasant side effects. These side effects can be lessened or eliminated with palliative care. Palliative care may help you have a better quality of life as you deal with cancer treatments, and it can be given at the same time as active treatment of ALL. Talk to your doctor if you would like to learn more about how to manage treatments for leukemia.
Children with ALL have a better prognosis than adults with this disease. About 4 out of 5 people who die from ALL are adults. Children with ALL have better survival rates — while 89 percent of children and teens under the age of 20 live for at least five years after being diagnosed, that number drops to 37 percent in adults over the age of 20.
Certain characteristics called prognostic factors tell you whether your outlook is likely to be better or worse. People with these factors have a higher chance of having a good prognosis:
Some gene changes can increase your risk of having a worse outcome. These changes include:
If you would like to know more about your outlook, talk to your health care team. Your doctors can help you understand your prognostic factors. They can also tell you more about how different treatment options may affect your outcome.
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