Diagnosing cancer

How is cancer diagnosed?

Unfortunately, there is no single test that can accurately diagnose cancer. A large number of tests are necessary to determine whether a person has cancer, or if another condition (such as an infection) is mimicking the symptoms of cancer. Sometimes, it is necessary to repeat testing if the child's condition changes, if a sample collected was not of good quality, or an abnormal test result needs to be confirmed. The correct diagnosis is necessary in order to determine treatment. In addition to a complete medical history and physical examination, diagnostic procedures for cancer may include one, or more of, the following:

• Complete blood count (CBC) - a measurement of size, number, and maturity of different blood cells in a specific volume of blood. Abnormal cells may indicate cancer. Variation in the normal number, size and maturity of cells may indicate a problem.
• Bone marrow aspiration and biopsy - a procedure that involves a small amount of bone marrow fluid and tissue, usually taken from part of the hip bones, to be examined for the number, size, and maturity of blood cells or abnormal cells. There are many cancers that can start or spread to the bone marrow.
• Spinal tap/lumbar puncture - a procedure to evaluate the fluid around the spine and brain for pressure or infection and to detect any abnormal cells. A special needle is placed into the lower back, into the spinal canal. This is the area around the spinal cord. The pressure in the spinal canal and brain can then be measured. A small amount of cerebral spinal fluid (CSF) can be removed and sent for testing to determine if there is an infection or other problem. CSF is the fluid that bathes your child's brain and spinal cord.
• Lymphangiogram (LAG) - an imaging study that can detect cancer cells or abnormalities in the lymphatic system and structures. It involves a dye being injected into the lymph system.
• Ultrasound (Also called sonography) - a diagnostic imaging technique which uses high-frequency sound waves and a computer to create images of blood vessels, tissues and organs. Ultrasounds are used to view internal organs as they function and to assess blood flow through various vessels. Tumors in the abdomen, liver and kidneys can often be seen with an ultrasound.
• Biopsy of the tumor - a procedure in which a sample of tissue is removed from the tumor and examined under a microscope. Biopsies may be necessary for a diagnosis, since there are different types of cancer.
• Bone scans - pictures or x-rays taken of the bone after a dye has been injected that is absorbed by bone tissue. These scans are used to detect tumors and bone abnormalities.
• X-rays - diagnostic tests which use invisible electromagnetic energy beams to produce images of internal tissues, bones and organs onto film. X-rays may be taken of any part of the body to detect tumor (or cancer) cells.
• Computed tomography scan (Also called a CT or CAT scan) - a diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce cross-sectional images (often called slices), both horizontally and vertically, of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat and organs. CT scans are more detailed than general x-rays.
• Magnetic resonance imaging (MRI) - a diagnostic procedure that uses a combination of large magnets, radiofrequencies and a computer to produce detailed images of organs and structures within the body.
• Blood tests - to evaluate electrolytes, liver function, kidney function, presence of infection, tumor markers (chemicals released by a tumor) or genetic testing. Genetic counseling may be recommended to families that are found or suspected to have an inherited predisposition to developing cancer, in order to identify other family members who may be at increased risk.
• Surgery - may be necessary to perform a biopsy, remove tumors, remove entire organs affected by disease and to look for tumors that may not be detected with diagnostic imaging.