Definition
Acute lymphoblastic leukemia (ALL) is a cancer of the blood and bone marrow. Lymphocytes are a type of white blood cell. With ALL, the bone marrow makes too many of these cells.
Leukemia cells do not function normally. In this case, they cannot fight infections. This means that the person is more likely to become infected with viruses or bacteria. The cancerous cells also overgrow the bone marrow. This forces other normal components, like platelets out. Platelets are needed to help the blood clot. As a result, people with leukemia may bleed more easily.
Causes
The cause of ALL is unknown. Research shows that certain risk factors are associated with the disease.
Risk Factors
Risk factors that 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 paint manufacturing and use)
- Certain genetic disorders, such as Down syndrome, Bloom syndrome, Fanconi's anemia, ataxia-telangiectasia, neurofibromatosis, Shwachman 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
These symptoms may be caused by other, less serious health conditions. You should see a doctor if you or your child is experiencing:
- Weakness
- Tiredness
- Fever
- Pale skin
- 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
Diagnosis
Your doctor will ask about your symptoms and medical history. A physical exam will be done. The doctor may also check for swelling of the liver, spleen, or lymph nodes. You will likely be referred to an oncologist. This is a doctor who specializes in treating cancer.
Tests may include the following:
- Blood tests
- Bone marrow aspiration
- Bone marrow biopsy
- Spinal tap
- Routine microscopic exam—examination of a sample of blood, bone marrow, lymph node tissue, or cerebrospinal fluid
- Cytogenetic analysis—a test to look for certain changes of the chromosomes (genetic material) of the lymphocytes; certain genetic abnormalities include:
- Relocation of genetic material from one chromosome to another
- Presence of a particular gene
- Presence of a variant gene, which controls an enzyme that influences folate metabolism
- Immunophenotyping—examination of the proteins on cell surfaces and the antibodies produced by the body; to distinguish lymphoblastic from myeloid leukemia and determine types of therapy
- Tests to help the doctor see the structures in your body:
- Chest x-ray
- Computed tomography (CT) scan
- Magnetic resonance imaging (MRI) scan
- 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 plan for you. Treatment of ALL is done in two phases. First, remission induction therapy is used to kill leukemia cells. Then, maintenance therapy is used to kill any remaining leukemia cells. Cells left behind could grow and cause a relapse. Treatment options include:
Chemotherapy
Chemotherapy is the use of drugs to kill cancer cells. It may be given by pill, injection, and via a catheter. The drugs enter the bloodstream and travel through the body. It kills mostly cancer cells, but also some healthy cells.
Clinical trials are now underway to test drugs. One drug is imatinib (Gleevec). This drug is used to treat chronic myelogenous leukemia (CML). It helps to prevent the function of genes associated with ALL.
Some ALL may spread to the brain and spinal cord. In this case, intrathecal chemotherapy may be used. Chemotherapy drugs are placed directly into the spinal column.
Radiation Therapy
Radiation therapy is the use of radiation to kill cancer cells and shrink tumors. For ALL, external radiation therapy is used. The radiation is directed at the tumor from outside the body. This type of treatment is used for ALL that has 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). These will replace blood-forming cells destroyed by cancer treatment. Stem cells are removed from the blood or bone marrow of the patient or donor. They are then infused into the patient.
Biologic Therapy
This process is still being tested in clinical trials. This is the use of medications or substances made by the body. The substance is used 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
People treated for ALL in their youth may have a risk of cancer later in life. A recent study found that they are more likely than the general population to develop a secondary cancer. The exact type of cancer can vary. It is important that people who have had ALL be carefully watched for new cancer development. These screenings should be carried out through their lifetime.