Acute Lymphoblastic Leukemia (ALL)

Overview

Acute lymphoblastic leukemia (ALL) is a cancer of the blood and bone marrow, the soft tissue inside bones where blood cells are made. In ALL, the marrow produces large numbers of immature white blood cells called lymphoblasts that do not work properly and crowd out healthy blood cells. "Acute" means it develops and worsens quickly, so it needs prompt treatment.

ALL is the most common cancer in children, although it also occurs in adults. Because the abnormal cells take over the bone marrow, people develop shortages of normal red cells, white cells, and platelets, leading to anemia, infections, and bleeding. With modern treatment, many people, especially children, can be cured, though it remains a serious illness that requires intensive care from a specialist team.

Symptoms

Symptoms come on over days to weeks as healthy blood cells are crowded out:

• Fatigue, pallor, and breathlessness from anemia
• Frequent or persistent infections and fevers from low normal white cells
• Easy bruising, bleeding gums, or tiny red spots on the skin from low platelets
• Bone or joint pain
• Swollen lymph nodes, and sometimes a swollen liver or spleen
• Loss of appetite and unintended weight loss
• Headaches or other symptoms if the cancer spreads to the brain or spinal fluid

These symptoms can resemble other illnesses, so blood tests are needed to make the diagnosis.

Causes

ALL begins when developing lymphocytes in the bone marrow acquire genetic changes that make them multiply uncontrollably and fail to mature. In most cases the exact reason these changes occur is unknown, and ALL cannot be predicted or prevented in an individual. It is not contagious and is rarely inherited.

Certain factors are linked to a higher risk, including some genetic conditions (such as Down syndrome), previous treatment with chemotherapy or radiation, and exposure to high levels of radiation. However, most people who develop ALL have no identifiable risk factor, and most people with these risk factors never develop the disease.

Risk Factors

• Young age (it is most common in children), with a second rise in older adults
• Certain inherited conditions, such as Down syndrome
• Previous chemotherapy or radiation therapy
• Exposure to high levels of radiation
• A sibling with ALL (a small increase in risk)

Diagnosis

Diagnosis involves blood and bone marrow tests, then detailed analysis to guide treatment:

• Blood tests: A full blood count often shows abnormal numbers of blood cells and may reveal leukemia cells.
• Bone marrow examination: A sample of marrow confirms the diagnosis and identifies the type of leukemia.
• Specialized testing: Genetic and molecular tests on the cells classify the leukemia and help predict its behavior and response to treatment.
• Spinal fluid test: To check whether the leukemia has reached the brain and spinal cord.

Treatment

ALL is treated intensively, usually over a planned series of phases that can last a couple of years:

• Chemotherapy: The main treatment, given in combinations and phases to destroy leukemia cells and prevent return. See chemotherapy-induced disorders for its side effects.
• Central nervous system treatment: Chemotherapy given into the spinal fluid, and sometimes radiation, to treat or prevent spread to the brain.
• Targeted therapy: Drugs aimed at specific genetic features of the leukemia in certain subtypes.
• Stem cell (bone marrow) transplant: For some higher-risk cases or relapses.
• Immunotherapy: Newer treatments that harness the immune system, used in selected situations.
• Supportive care: Transfusions, infection treatment, and management of side effects throughout.

Outcomes have improved greatly, and many children and a substantial number of adults achieve long-term remission or cure.

Prevention

There is no known way to prevent acute lymphoblastic leukemia, since it usually arises from random genetic changes that cannot be controlled. There is no screening test for it in people without symptoms. The most useful steps are:

• Seeking medical attention promptly for persistent unexplained symptoms
• Ensuring children with conditions such as Down syndrome receive recommended monitoring
• Following safety guidance to avoid unnecessary high-dose radiation exposure

When to See a Doctor

See a doctor promptly if you or your child has persistent, unexplained symptoms such as ongoing fatigue and pallor, frequent infections or fevers, easy bruising or bleeding, bone pain, or swollen lymph nodes. Seek urgent or emergency care for:

• High fever, especially with shaking chills, or signs of serious infection
• Heavy or uncontrolled bleeding
• Severe breathlessness, confusion, or collapse

People already diagnosed with ALL should follow their care team's instructions and report fever immediately, as infection can be dangerous when the immune system is weakened.

Related Topics

Frequently Asked Questions

References

1. National Cancer Institute (NCI). Acute lymphoblastic leukemia.
2. American Cancer Society. Acute lymphocytic leukemia.
3. MedlinePlus, U.S. National Library of Medicine. Acute lymphocytic leukemia.
4. Leukemia & Lymphoma Society. Acute lymphoblastic leukemia.