Acute Lymphocytic Leukemia (ALL)

What is Adult Acute Lymphocytic Leukemia?

Adult acute myeloid lymphocytic leukemia (ALL), also referred to as acute lymphoblastic leukemia or acute lymphoid leukemia, is a type of cancer in which the bone marrow makes too many immature white blood cells (lymphoblasts). About 3,800 new cases of ALL are diagnosed each year in the United States. Although rare compared to other types of cancer such as colon, lung, prostate or breast cancer, ALL is the most common type of leukemia in children under the age of 19, but can occur at any age. The physicians at Rocky Mountain Cancer Center (RMCC) and the Rocky Mountain Blood and Marrow Transplant Program (RMBMTP) are specialists in the care of patients with leukemia.

ALL results from an acquired (not inherited) genetic injury to the DNA of a single cell in the bone marrow, resulting in uncontrolled growth and accumulation of undeveloped cells called “leukemic blasts,” which cannot function as normal blood cells. The production of normal marrow cells is blocked, leading to a deficiency of red blood cells, blood-clotting platelets and infection-fighting normal white cells. When this happens, infection, anemia or easy bleeding may occur.

What causes ALL?

The cause of ALL is unknown. It is not contagious and is not inherited. Few factors have been associated with increased risk of developing ALL. Exposure to high doses of radiation, such as that experienced by people living near the site of the Chernobyl power plant explosion or Japanese survivors of the atomic bomb detonations, can cause changes in the bone marrow DNA and could be one risk factor. Past chemotherapy or radiation treatment and having certain genetic disorders such as Down syndrome could also increase the risk of developing ALL.

How is ALL diagnosed?

Possible signs of adult ALL include fever, feeling tired, shortness of breath during physical activity and easy bruising or bleeding. Most patients feel a loss of well-being, may tire easily or have a pale complexion from anemia. Discomfort in the bones and joins may be present. A doctor should be consulted if any of the following problems occur: fever, shortness of breath, easy bruising or bleeding, petechiae (flat, pinpoint spots under the skin caused by bleeding), weakness or feeling tired, or loss of appetite and weight loss.

Doctors use tests that examine the blood and bone marrow to detect and diagnose adult ALL, including:

Physical examination and history

Complete blood count

Number of red blood cells, white blood cells, and platelets

Amount of hemoglobin (protein that carries oxygen) in the red blood cells

Portion of the sample made up of red blood cells

Immunophenotyping (identifying cells based on the types of antigens or markers on the surface of the cell to diagnose the subtype of ALL)

Cytogenetic examination of tissue to analyze the number and shape of the chromosomes of cells

Peripheral blood smear (checking for the presence of blast cells, number and kinds of white blood cells, number of platelets, and changes in the shape of blood cells)

Bone marrow aspiration and biopsy (looking for abnormal cells)

Once ALL has been diagnosed, tests may be conducted to see if the cancer has spread to other parts of the body. The spread of most cancers is usually described as stages. This is not true for acute leukemia. A doctor may use chest x-rays, lumbar puncture (spinal tap), ultrasound, or a CT (CAT) scan to determine if the cancer has spread.

There is no standard staging system for adult ALL; instead the disease is described as untreated, in remission or recurrent. The subtype of the disease is important. Different therapies may be used and the likely course of the disease and the prognosis may be different.

• In untreated adult ALL, the disease is newly diagnosed and has not yet been treated.
• In adult ALL in remission, the complete blood count is normal, less than five percent of the cells in the bone marrow are blasts, and there are no signs or symptoms of leukemia in the brain, spinal cord, or elsewhere in the body.
• In recurrent adult ALL, the cancer has come back after it has been treated. ALL may recur in the blood, bone marrow, or rarely, other parts of the body (like spinal fluid).

The prognosis (chances of recovery) and treatment options depend on the age of the patient, subtype of ALL, a test to look for certain DNA changes in the ALL cells (the “karyotype” or “chromosome” test) used to determine whether the patient received chemotherapy in the past to treat a different cancer, history of a blood disorder, whether the cancer has spread to the central nervous system and whether the cancer has been treated before.
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ALL can develop from lymphocytes that are in different stages of development. The principle subtypes of ALL are determined by special tests called immunophenotyping. The subclassification of cell types is important because it helps to determine the best treatment for each type of leukemia. The principle subtypes are B lymphocyte and T lymphocyte.

• B lymphocytic subtypes are identified by finding cell surface markers on the leukemic blasts that are identical to those on normal B lymphocytes. About 85 percent of ALL cases are the precursor B or B cell subtype.
• T lymphocytic subtypes are identified by finding cell surface markers on the leukemic blasts that are identical to those on normal T lymphocytes. About 15 percent of ALL cases are of the T cell subtype.

Physicians may also use chromosome abnormalities to assist in subclassifying ALL. For example, a change in chromosome number 22 occurs in a small percentage of children and a larger percentage of adults with placing the patient in a higher risk category ALL.
Examples of higher risk types of ALL may be t4:11 or t9:22 (Philadelphia Chromosome).

What are the treatment options?

There are different types of treatment for patients with adult ALL, and the treatment usually is done in two phases:

• Remission induction therapy to get rid of all the leukemia cells and put the cancer in remission. Treatment may include combination chemotherapy or CNS prophylaxis therapy with or without radiation therapy to the brain.
• Maintenance therapy, which is the second phase begun after remission, to kill any remaining leukemia cells that may not be active but could cause a relapse. Treatment may include combination chemotherapy, chemotherapy with stem cell transplantation, or CNS prophylaxis therapy with or without radiation therapy to the brain.

Treatment of adult ALL depends on the subtype of ALL and may include combination chemotherapy, radiation therapy, chemotherapy and stem cell transplantation, and biologic therapy using the patient’s immune system to fight the cancer. Treatments are tailored to individual patients according to age and risk of recurrence of the ALL.