Acute lymphoblastic leukemia (ALL) — sometimes called acute lymphocytic leukemia — is a type of blood cancer. The American Cancer Society estimates that nearly 5,700 people will be diagnosed with ALL in the United States in 2021. ALL is the most common type of leukemia in children, and children under 5 and adults over 50 have a higher risk of developing the condition. Additionally, ALL is slightly more prevalent in males than in females.
Treatments are available for managing ALL, and many people with the condition successfully achieve complete remission, meaning all signs of cancer cells disappear. Understanding the condition, causes, and potential treatments can help you understand how ALL progresses and what to expect when you or a loved one have been diagnosed.
Leukemia arises in the bone marrow — tissue found inside certain bones that is responsible for making new blood cells. Leukemia develops when blood cells begin to grow and multiply uncontrollably. These cancerous cells crowd out normal blood cells and may prevent them from carrying out their usual functions.
Leukemias can be classified as acute or chronic. Acute leukemia cells grow and divide rapidly and can quickly cause increasingly severe symptoms. If you have acute leukemia, you will need to start treatment right away.
Leukemias are also usually referred to as myeloid or as lymphoblastic. Lymphoblastic leukemias like ALL are cancers that affect white blood cells (WBCs) called lymphocytes. These cells are a part of the immune system that help the body stay healthy and fight off infections.
Leukemias, like other types of cancer, are caused by changes in your genes. When parts of genes are damaged, mutated, broken, or deleted, they can lead to cancer.
Some gene changes are passed down through families. These changes are found in all cells and are present at birth. Some of the genetic conditions that can increase a person’s risk of ALL include:
Most of the time, ALL develops from gene changes that occur after birth. These changes are not passed down from parents to children. Usually, it’s not known why these changes occur. These factors are more likely to affect adults, and they don’t usually play a role in childhood acute lymphoblastic leukemia.
Factors that can cause gene damage and increase the likelihood of developing cancer-causing mutations include:
Eliminating risk factors may decrease your chance of getting ALL, but there is no way to completely prevent this disease. Most people who have these risk factors never develop ALL, and most people with ALL don’t have any risk factors. There is no way to know for sure who will get ALL or what causes any individual case of ALL.
ALL has two main subtypes based on which type of lymphocyte is affected. The most common subtype is B-cell lymphoblastic leukemia. About 3 out of 4 adults with ALL have the B-cell subtype. The other subtype is T-cell lymphoblastic leukemia.
B-cell and T-cell leukemias can also be categorized into different subtypes based on which genetic changes are present in the cancer cells. About 20 percent to 30 percent of adults with B-cell ALL have a genetic change called the Philadelphia chromosome. This change is an example of a chromosome translocation, in which two pieces of DNA are linked together. Other translocations can also cause ALL. Additionally, this cancer can be caused by having too many or too few chromosomes.
Knowing your ALL subtype and which gene changes you have can be important, because it helps determine which treatments will likely be the most helpful, what your prognosis looks like, and how long you’ll need to receive those treatments.
Because leukemic cells grow quickly and crowd out normal blood cells, ALL can lead to low levels of the different types of blood cells. Having low numbers of germ-fighting white blood cells often leads to frequent infections. Having low red blood cell levels — a condition called anemia — can make you feel tired or dizzy, or make it difficult to catch your breath. Low numbers of platelets, which are responsible for forming blood clots, can cause bruising, nosebleeds, and small red spots on the skin (called petechiae).
Many people with ALL also have other symptoms such as:
If there is a chance that you may have ALL based on your symptoms, your doctor will do additional tests before diagnosing you. Some of these tests require you to give a blood sample, which is then sent to a laboratory for testing. One common blood test is a complete blood count (CBC). A CBC shows how many of each type of blood cell you have. Other blood tests can also help the doctor see if your blood contains any lymphoblasts (immature WBCs), as these are a sign of cancer.
To know for sure whether you have ALL, your doctor will also generally need to do bone marrow tests. These tests involve removing a sample of bone marrow from the hip bone with a needle. The test is often done in two parts. First is a bone marrow aspiration, during which some of the bone marrow fluid is removed. Next comes the bone marrow biopsy, which entails removing some of the solid bone marrow tissue. These samples will be studied under a microscope to see whether any cancer cells are present.
If leukemia cells are found in the biopsy sample, then the laboratory technicians may perform additional tests on the bone marrow or blood samples. These tests help the doctor learn more about the genes and proteins found in your cancer cells. They include:
You may also need imaging tests at various points before and during treatment for ALL. Imaging tests can help the doctor see whether the leukemia has spread to other places in the body or look for problems in different organs. Imaging tests can include X-rays, ultrasounds, CT scans, or MRI.
People with ALL often go through a few different treatment phases. The first phase, which usually kills most of the leukemia cells, is called induction therapy. Induction therapy is followed by consolidation therapy, which helps destroy any remaining cancer cells that were left behind.
If a person goes into remission after consolidation therapy, they then often use maintenance therapy for a couple of years to help keep the cancer away. During these stages, a person may also have treatments to kill leukemia cells in the brain and spinal cord, which are together known as the central nervous system (CNS).
You may receive one or a combination of these drugs. Chemotherapy is also often combined with targeted therapy or other treatments.
Pediatric ALL is often treated with lower doses of chemotherapy over the course of several years.
Targeted therapy treatments can identify and block specific genes or proteins found in your cancer cells. For ALL, targeted therapies often include monoclonal antibodies, which attack proteins found on the outer surface of leukemia cells. Targeted therapies may also include tyrosine kinase inhibitors, which block specific proteins that make cancer cells grow out of control.
Radiation therapy is a treatment that uses X-rays to kill cancer cells in the body. Adults with ALL that has spread to the CNS may receive radiation treatments. Radiation can also be used to reduce symptoms of ALL.
Some people with ALL may also receive a stem cell transplant after receiving aggressive chemotherapy treatments. Chemotherapy kills not only cancer cells, but also normal blood cells, so a stem cell transplant provides the body with new, healthy blood cells. During this procedure, old, damaged stem cells will be destroyed and then replaced with new blood stem cells, which are able to form all of the different types of blood cells normally found in the body. These new stem cells may be the person’s own healthy stem cells that had been extracted in advance and treated, or they may come from a donor.
New treatments are constantly being developed and improved. One promising new treatment option is called Chimeric Antigen Receptor T-cell (CAR-T) therapy. During this treatment, your own immune system is trained to fight off cancer cells. CAR T-cell therapy is approved for ALL that is advanced or has come back following initial therapy.
Read more about treatment options for ALL here.
About 75 percent to 80 percent of adults and over 95 percent of children who have ALL go into complete remission, which means that tests can’t find any signs of cancer cells. For about 90 percent of children, ALL does not come back within 10 years of going into remission and they are considered to be cured. Adults with ALL tend to have a worse outlook. About 37 percent of adults will live for at least 5 years after being diagnosed.
However, there are several factors that play a role in what your individual prognosis may look like. For example, older adults with ALL are more likely to have a worse outlook than younger adults. Older adults are more likely to have gene changes and additional health problems that can lead to a worse prognosis.
Another prognostic factor for ALL is your white blood cell count at the time you are diagnosed. People with B-cell ALL who have fewer than 30,000 WBCs — and people with T-cell ALL who have fewer than 100,000 WBCs — are more likely to do better.
Gene changes and mutations can also affect your outlook. If you have the Philadelphia chromosome, too many copies of chromosome 21, or too few chromosomes overall, you have a higher chance of a poorer outlook. However, if you have a higher-than-normal number of chromosomes or if you have a translocation of chromosomes 12 and 21, your prognosis may be better.
Finally, how quickly you respond to treatments can determine your prognosis. Going into remission four or five weeks after you start treatment is a good sign. On the other hand, if you never reach complete remission, you may have a worse outlook.
A cancer diagnosis may be made easier with the support of others who are going through something similar. MyLeukemiaTeam is the social network for people with leukemia and their loved ones. Members come together to ask questions and share their experiences of life with all types of leukemias.
Have you been recently diagnosed with ALL? Are you in the process of deciding on a treatment plan? Share your experience by commenting below, or begin a new conversation at MyLeukemiaTeam.