Diagnosis

Doctors use many tests to diagnose cancer and learn more about the disease. Some tests may also determine which treatments may be the most effective. For most types of cancer, a biopsy is the only way to make a definitive diagnosis of cancer. If a biopsy is not possible, the doctor may suggest other tests that will help make a diagnosis. Imaging tests may also be used. Your doctor may consider these factors when choosing a diagnostic test:

• Age and medical condition
  
  
• The type of cancer suspected
  
  
• Severity of symptoms
  
  
• Previous test results

The following tests may be used to diagnose ALL:

Blood tests. If the doctor believes a person has ALL based on the symptoms, he or she will examine the levels of different types of cells in the patient’s blood through a test called a complete blood count (CBC). Low levels of red blood cells and platelets and high levels of white blood cells are common in ALL but can also be a sign of other medical problems. In addition, a blood smear may be examined under a microscope to determine if lymphoblasts or other abnormal cells are present.

Bone marrow biopsy. If the blood test shows abnormalities in the number or appearance of the white blood cells, a bone marrow biopsy will be done. In a bone marrow biopsy, the doctor takes a sample of marrow with a needle, usually from the back of the hipbone. The patient is given medication to numb the area beforehand. The cells from the marrow, along with the cells from the blood, are then examined under a microscope to determine the type of leukemia. The pathologist (a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease) may use this bone marrow sample for other tests, such as cytogenetics and immunophenotyping.

Flow cytometry and cytochemistry (immunophenotyping). In these tests, cancer cells are treated with chemicals or dyes that provide information about the leukemia and its subtype. ALL cells have distinctive markers (cell surface proteins) on their surface. The pattern of these markers is called the immunophenotype. These tests are used to distinguish ALL from other types of leukemia, which can also involve lymphocytes. Both tests can be done from a blood sample.

Cytogenetics. Cytogenetics is the analysis of the number and arrangement of a cell’s chromosomes (long pieces of DNA that contain genes). People with ALL may have specific chromosomal changes, including the addition or loss of certain chromosomes, as well as translocations, which means that parts of one chromosome have been transferred to another chromosome. These changes can be seen under a microscope using special techniques.

About 30% of adults with ALL have a change in their chromosomes called the Philadelphia chromosome. The Philadelphia chromosome is an example of a translocation, which, in this specific instance, means that genetic material from chromosome 9 breaks off and attaches to chromosome 22. In this way, two specific genes called BCR and ABL are brought together and form a single fusion gene called BCR-ABL. Some people may have other types of translocations. For example, many children with ALL have a translocation between chromosomes 12 and 21. These genes are called TEL and AML1. This information helps doctors decide which treatment is best.

Lumbar puncture (spinal tap). A lumbar puncture is a procedure in which a doctor takes a sample of cerebral spinal fluid (CSF) to look for cancer cells, blood, or tumor markers (substances found in higher than normal amounts in the blood, urine, or body tissues of people with certain kinds of cancer). Because ALL tends to spread to the CSF surrounding the brain, spinal taps are done regularly during the treatment of ALL. Doctors generally give an anesthetic to numb the lower back before the procedure.

Imaging tests. A computed tomography (CT or CAT) scan (test that creates a three-dimensional picture of the inside of the body) or magnetic resonance imaging (MRI, test that uses magnetic fields, not x-rays, to produce detailed images of the body) may be used to learn more about the cause of symptoms or to help diagnose infections in patients with ALL. They are not regularly used for assigning a classification (see next section) to ALL since the disease is usually spread throughout the bone marrow and blood at the time of diagnosis. These tests may not be done for every patient.

Learn more about what to expect when having common tests, procedures, and scans.

Find out more about common terms used during a diagnosis of cancer.