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    T-cell Acute Lymphoblastic Leukemia

    T-cell acute lymphoblastic leukemia, or T-ALL, is an aggressive bone marrow and blood cancer. Treatment can cure up to 80% of children but typically less than 50% of adults.

    What is T-cell acute lymphoblastic leukemia?

    T-cell acute lymphoblastic leukemia is an aggressive blood cancer that affects T-cell development. T-cells are white blood cells made in the bone marrow (the soft inner part of bones). They help the body to fight off infections.

    T-cells from the bone marrow travel to the thymus. The thymus is a small organ found behind the breastbone in a space called the mediastinum (meaning “midway”). T-cells within the thymus undergo abnormal transformations in T-ALL and become cancerous during this development stage.

    The term “acute” means the sudden and severe onset of a disorder that can progress quickly. T-ALL often spreads to the central nervous system (brain and spinal cord). Tumors behind the breastbone (mediastinal masses) occur in about 75% of T-ALL cases.

    T-cell Acute Lymphoblastic Leukemia facts and stats

    • Median childhood onset occurs around age nine and median adult onset occurs around age 30.
    • Around 75% of children and around 60% of adults with T-ALL remain cancer free after five and three years, respectively.
    • Around one-third of patients experience T-ALL relapse (return of the cancer) within one to two years.T-ALL accounts for 25% of adult and 10-15% of childhood cases of acute lymphoblastic leukemia (ALL).

    Causes and risk factors of T-cell Acute Lymphoblastic Leukemia

    Researchers think several genetic changes (mutations) cause T-ALL. These changes interfere with normal T-cell development within the thymus. The cause of these genetic mutations is unknown.

    Risk factors for T-ALL include:

    • Family history of leukemia, especially siblings
    • Genetic conditions, such as Down syndrome
    • Previous exposure to X-ray, radiation, or chemotherapy

    Signs and symptoms of T-cell Acute Lymphoblastic Leukemia

    Signs and symptoms of T-cell acute lymphoblastic leukemia may include:

    • Abdominal pain due to an enlarged liver or spleen
    • Breathing problems/respiratory failure due to fluid in the lungs (pleural effusion) or mediastinal tumors
    • Easy bruising
    • Excessive bleeding (especially of the nose and gums)
    • Fatigue
    • Lymph node swelling
    • Recurrent fevers/infections

    Diagnosing T-cell Acute Lymphoblastic Leukemia

    To diagnose T-ALL, your doctor performs a physical exam and asks about your medical history.

    Tests may include:

    • Blood tests: Doctors take a sample of your blood to count the number of platelets, white blood cells, and red blood cells. Blood tests also measure liver and kidney function and find signs of inflammation and infection.
    • Bone marrow aspiration or biopsy: Your doctor removes small samples of bone marrow or bone tissue for analysis using a thin, hollow needle. This is the most common and reliable method for T-ALL diagnosis.
    • Imaging: Imaging determines cancer severity and locates affected lymph nodes and tumors. It also detects enlarged organs, such as the liver or spleen. Imaging may include:
      • Chest X-rays
      • Computed tomography (CT) scans
      • Echocardiograms
      • Magnetic resonance imaging (MRI) scans
      • Positron emission tomography (PET) scans
      • Ultrasounds (US)
    • Lumbar puncture (spinal tap): Your doctor removes a small amount of cerebrospinal fluid (CSF) from near the spinal cord in your lower back using a needle. CSF surrounds and protects your brain and spinal cord. Results show whether the cancer has spread into this fluid.
    • Genetic testing: This test helps to determine the T-ALL subtype by detecting abnormal genes or chromosomes. Results guide your doctor’s recommended treatment.

    Treatments for T-cell Acute Lymphoblastic Leukemia

    Treatment depends on your T-ALL subtype, current symptoms, response to treatment, and general health. Other health conditions that you have might affect treatment options.


    Treatment options for T-ALL may include:

    • Chemotherapy: Chemotherapy drugs kill cancer cells. They are administered either in pill form or as injections into a vein, muscle, underneath the skin, or into the fluid around the spinal cord (intrathecal). Children often tolerate higher doses of chemotherapy better than adults.
    • Radiation: Doctors use focused beams of energy to destroy cancer cells while reducing harm to healthy tissues. Radiation may treat T-ALL in the thymus, brain, or spinal cord.
    • Targeted therapy: Targeted drugs stop the growth of cancer cells or kill them while minimizing harm to nearby healthy tissues. Targeted therapy options are limited for T-ALL.
    • Stem cell transplant (bone marrow transplant): Your doctor may replace unhealthy stem cells (blood-forming cells in bone marrow) with healthy stem cells. Replacement stem cells may come from a donor or your own healthy cells.
    • Clinical trials: Studies at specific medical centers may give eligible patients access to promising treatments currently under development. These treatments are usually not widely available.
    • Supportive therapies: Supportive care may replace or supplement more intensive treatments, such as chemotherapy. They can provide relief from cancer symptoms or side effects from cancer treatments. Supportive therapies may include:
      • Antibiotics to treat recurrent infections
      • Blood transfusions if low platelet and red blood cell levels are too low
      • Counseling
      • Diet
      • Pain management
      • Physical exercise

    Helpful resources

    Support can make a significant difference when you face a cancer diagnosis. You can connect with others who understand these challenges through our peer support programs. We offer an online support community and a mentoring program. We also have a directory of resources to help patients, families, and caregivers.

    Clinical Trials Hub: A resource for leukemia patients and caregivers

    Do you have questions about clinical trials? On our new Clinical Trials Hub learn how clinical trials are developed or if they are right for you. You can also use the new Search Tool to see if there is a current leukemia-focused trial you would qualify for.

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