(Acute Lymphocytic Leukemia, ALL)
Definition
Acute lymphoblastic leukemia (ALL) is a cancer of the blood and bone marrow, in which the bone marrow makes too many lymphocytes (a type of white blood cell). ALL begins in immature lymphocytes and progresses very quickly. It may occur at any age, but is most common in children, or as the end stage of a chronic leukemia of adults called chronic lymphocytic leukemia . Childhood ALL was one of the first cancers for which effective chemotherapy was developed and remains highly curable today.
Cancer occurs when cells in the body (in this case, lymphocytes) become abnormal, and divide without control or order. Leukemia is cancer of the white blood cells and their parent cells. Leukemia cells do not function normally and cannot do what normal blood cells do, such as fight infections. This means that a person with leukemia is more likely to become infected with viruses or bacteria. Because the cancerous cells also overgrow the bone marrow, they can force out other normal components, such as the cells that make platelets. Platelets are necessary for proper blood clotting. So people with untreated leukemia may also have unexpected bleeding or may bruise easily.
Causes
The cause of ALL is unknown, but research shows that certain risk factors are associated with the disease.
Risk Factors
A risk factor is something that increases your chance of getting a disease or condition.
The following factors increase your chance of developing ALL:
• Sex: male
• Race: white
• Age: children and elderly (adults older than 70)
• Previous chemotherapy or radiation therapy treatment
• Exposure to atomic bomb radiation or nuclear reactor accident
• Exposure to toxic chemicals such as benzene (common in agriculture, dye works, and pain manufacturing and use)
• Certain genetic disorders, such as Down’s syndrome , Bloom syndrome, Fanconi's anemia, ataxia-telangiectasia, neurofibromatosis, Schwachman syndrome, IgA deficiency, and congenital X-linked agammaglobulinemia
The following risk factors are specific to childhood ALL:
• Having a brother or sister with leukemia
• Race: white or Hispanic
• Living in the United States
• Exposure to x-rays before birth
• Exposure to radiation
• Previous chemotherapy or other treatment that weakens the immune system
• Certain genetic disorders (see above)
Symptoms
Symptoms include:
• Weakness
• Tiredness
• Fever
• Paleness (a sign of anemia )
• Easy bruising or bleeding
• Petechiae (flat, pinpoint spots under the skin caused by bleeding)
• Shortness of breath
• Weight loss
• Loss of appetite
• Bone or joint pain
• Stomach pain
• Pain or a feeling of fullness below the ribs
• Painless lumps in the neck, underarms, stomach, or groin
• Swelling of the liver and/or spleen
These symptoms may also be caused by other, less serious health conditions. Anyone experiencing these symptoms should see a doctor.
Diagnosis
Your doctor will ask about your symptoms and medical history, and perform a physical exam. He or she may also check for swelling of the liver; spleen; or lymph nodes in the armpits, groin, or neck. You will likely be referred to an oncologist, a doctor who specializes in treating cancer.
Tests may include the following:
• Blood Tests – to check for changes in the number or appearance of different types of blood cells
• Bone Marrow Aspiration – removal of a sample of liquid bone marrow to test for cancer cells
• Bone Marrow Biopsy – removal of a sample of liquid bone marrow and a small piece of bone to test for cancer cells
• Spinal Tap – removal of a small amount of cerebrospinal fluid to check for cancer cells
• Routine Microscopic Exam – examination of a sample of blood, bone marrow, lymph node tissue, or cerebrospinal fluid
• Bone, Blood Marrow, Lymph Node Tissue, or Cerebrospinal Fluid Tests – to distinguish among types of leukemia
• Cytogenetic Analysis – a test to look for certain changes of the chromosomes (genetic material) of the lymphocytes; certain genetic abnormalities are associated with ALL including:
o The relocation of genetic material from one chromosome to another
o The presence of a particular gene (Ikaros)
o The presence of a variant gene, which controls an enzyme that influences folate metabolism
• Immunophenotyping – a process by which researchers examine the proteins on cell surfaces and the antibodies produced by the body. This helps distinguish lymphoblastic from myeloid leukemia and may also be used to determine what types of therapy are most likely to be effective.
• Chest X-ray – x-rays of the chest that may detect signs of lung infection or enlarged lymph nodes in the chest
• CT Scan – a type of x-ray that uses a computer to make pictures of structures inside the body
• MRI Scan – a test that uses magnetic waves to make pictures of structures inside the body
• Gallium Scan and Bone Scan – injection of a radioactive chemical into the bloodstream to detect areas of cancer or infection
• Ultrasound – a test that uses sound waves to examine masses and organs inside the body
Treatment
Talk with your doctor about the best treatment plan for you. Treatment of ALL is done is two phases: remission induction therapy (to kill leukemia cells) and maintenance therapy (to kill any remaining leukemia cells that could grow and cause a relapse). Treatment options include:
Chemotherapy
Chemotherapy is the use of drugs to kill cancer cells. It may be given in many forms including: pill, injection, and via a catheter. The drugs enter the bloodstream and travel through the body killing mostly cancer cells, but also some healthy cells. Drugs such as imatinib (Gleevec, which are used to treat chronic myelogenous leukemia (CML) that help prevent the function of genes associated with ALL are now being tested in clinical trials.
For ALL that has spread—or may spread—to the brain and spinal cord, intrathecal chemotherapy (chemotherapy drugs placed directly into the spinal column) may be used.
Radiation Therapy
Radiation therapy involves the use of radiation to kill cancer cells and shrink tumors. The type of radiation therapy usually performed to treat ALL is external radiation therapy . In external radiation therapy, the radiation is directed at the tumor from a source outside the body. This treatment is used for ALL that has spread—or may spread—to the brain and spinal cord.
Chemotherapy With Stem Cell Transplant
Chemotherapy is followed by a transplantation of stem cells (immature blood cells) to replace blood-forming cells destroyed by cancer treatment. Stem cells are removed from the blood or bone marrow of the patient or donor, and infused into the patient.
Biologic Therapy
Biologic therapy, which is still being tested in clinical trials, is the use of medications or substances made by the body to increase or restore the body's natural defenses against cancer. This type of therapy is also called biological response modifier therapy . Sometimes, very specific (monoclonal) antibodies are developed to target the leukemia cells specifically. Currently, monoclonal antibody therapy is restricted to clinical trails and not generally available.
Possible Development of New Cancers
One complication associated with ALL treatment is the development of new cancers later in the life (as opposed to a recurrence of the original ALL). In a recent study, researchers followed 2,169 children and adolescents who had achieved complete remission after treatment for ALL. They found that almost 11% of these patients developed secondary cancers of various types over a period of 30 years. This is substantially higher than the rate of similar cancers in the general population. It is critical, therefore, that young patients successfully treated for ALL are closely monitored throughout their adult lives for an increased risk of cancer. *
Prevention
There are no guidelines for preventing ALL since its cause is unknown.
