Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is a cancer of lymphocytes that live in the bone marrow, lymph nodes and spleen. ALL accounts for 20 percent of acute leukemia in adults, but is also the most common type of acute leukemia in children.

Acute lymphoblastic leukemia (ALL) usually causes illness suddenly, within days or weeks. Most problems are related to the replacement of normal bone marrow and diminished normal blood counts. ALL causes bone marrow failure, which leads to:

  • Low levels of red blood cells, which can cause fatigue and shortness of breath
  • Low platelet counts, which can cause bleeding
  • Low normal white blood cell counts, which can lead to infection
  • Vulnerability to bruising, bleeding and infections

In addition to these signs of bone marrow failure, ALL sometimes can cause enlarged lymph nodes, an enlarged liver or spleen, or pain in the bones or joints.

Acute lymphoblastic leukemia (ALL) is usually suspected when a test finds abnormal blood counts and leukemic cells, or blasts, appear in the blood. Then, the diagnosis is established by examination of the bone marrow via bone marrow aspiration and biopsy. ALL is diagnosed when the bone marrow aspirate and biopsy contains 20 percent or more immature cells called blasts, determined to be lymphoid in nature.

It's generally difficult to be certain of an ALL diagnosis simply by the appearance of cells under the microscope. Therefore, additional laboratory tests are normally needed.

One important test is immunophenotyping (also called flow cytometry), which determines whether the cells are lymphoid (ALL) rather than myeloid (AML), based on proteins expressed in the leukemia cells. Immunophenotyping also determines whether they are T or B lymphocytes. In addition, chromosome testing, called cytogenetics, is a critical part of the evaluation that helps determine the appropriate course of treatment.

The treatment of acute lymphoblastic leukemia (ALL) varies according to one's age, general condition at diagnosis and the results of the cytogenetic testing. Standard therapy for ALL has changed very little in the last 15 years or so, as the current strategy has been very effective at curing adults. The goal of treatment is a cure. Treatment can be divided into four phases:

  • First phase — induction chemotherapy
  • Second phase — consolidation chemotherapy
  • Third phase — maintenance chemotherapy
  • Fourth phase — central nervous system (CNS) prophylaxis

The first two phases use intensive chemotherapy medications designed to kill the leukemia cells that grow quickly. Complete therapy for ALL typically continues for two to three years.

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Reviewed by health care specialists at UCSF Medical Center.