Diagnosis

Doctors use many tests to diagnose cancer and determine if it has metastasized (spread). 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 be used to find out whether the cancer has metastasized. 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

In addition to a physical examination, the following tests may be used to diagnose childhood cancer:

Blood tests. Routine blood tests measure the number of different types of cells in a person’s blood. Levels of certain cells that are too high or too low can indicate the presence of cancer.

Biopsy. A biopsy is the removal of a small amount of tissue for examination under a microscope. Other tests can suggest that cancer is present, but only a biopsy can make a definite diagnosis. The type of biopsy performed depends on the location of the cancer. The sample removed from the biopsy is analyzed by a pathologist (a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease).

Bone marrow aspiration. A bone marrow biopsy is the removal of a sample of bone marrow, usually from the back of the hipbone, with a needle. The patient is given medication to numb the area beforehand and may be given conscious sedation (a type of anesthesia that uses pain relievers and sedatives to induce an altered state of consciousness). People who receive conscious sedation are usually able to speak and respond during the procedure and may not have any memory of the procedure afterward.

Lumbar puncture (spinal tap). A lumbar puncture is a procedure in which a doctor takes a sample of cerebrospinal 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). CSF is the fluid that flows around the brain and the spinal cord. Doctors generally give the child an anesthetic to numb the lower back before the procedure.

Computed tomography (CT or CAT) scan. A CT scan creates a three-dimensional picture of the inside of the body with an x-ray machine. A computer then combines these images into a detailed, cross-sectional view that shows any abnormalities or tumors. Sometimes, a contrast medium (a special dye) is injected into a patient’s vein to provide better detail.

Magnetic resonance imaging (MRI). An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. A contrast medium may be injected into a patient’s vein to create a clearer picture.

Ultrasound. An ultrasound uses sound waves to create a picture of the internal organs.

Positron emission tomography (PET) scan. A PET scan is a way to create pictures of organs and tissues inside the body. A small amount of a radioactive substance is injected into a patient’s body and absorbed by the organs or tissues being studied. This substance gives off energy that is detected by a scanner, which produces the images.

Scans or radioisotope studies. In these procedures, a material (called a tracer) is injected into the body and then followed with a special camera or x-ray to see where the material goes. These studies can find abnormalities in the liver, brain, bones, kidneys, and other organs.

Many of these tests may be repeated during and after treatment to determine the effectiveness of the treatment.

To learn more about what to expect during common diagnostic tests, read Cancer.Net: Tests and Procedures.

To learn about the terms used in this section, read the Cancer.Net Feature: Cancer Terms to Know: Newly Diagnosed.