How is neuroblastoma diagnosed?
A physical examination of the body is performed to feel for lumps. In this way, the abdomen may be felt (palpated) for a mass. An enlarged liver indicates that the cancer has spread to the liver. Tumors of the adrenal glands often cause high blood pressure and a fast heart rate.
Several tests may be done to look for the origin of the tumor and sites of metastases:
- A blood test, including a complete blood count (CBC), which is a test on the blood to look for anemia or other abnormalities.
- A blood chemistry test may be performed to detect elevated amounts of the sympathetic hormones dopamine and norepinephrine.
- A chest X-ray or abdominal X-ray may be helpful if positive.
- An abdominal ultrasound may be diagnostic if the tumor is located in the abdomen.
- A computed tomography (CT) scan, an imaging procedure in which a dye may be injected into a vein and is then taken up by organs and tissues, allowing any abnormalities to be seen more clearly on an X-ray.
- Magnetic resonance imaging (MRI), which uses a large magnet, radio waves, and a computer to produce images of various tissues of the body. If a contrast agent is used, it is injected into a vein; any lesions will "light up" after receiving the injection.
- A biopsy, a procedure in which cells or tissue are removed and then examined by a pathologist to detect cancer.
- A cytogenetic analysis, in which cells obtained from a tissue sample are examined for changes in the chromosomes and for the presence of n-myc.
- Bone marrow aspiration (removing a small amount of the liquid portion of bone marrow through a needle) and a bone marrow biopsy (removing a small sample of bone marrow tissue through a needle) allow a pathologist to examine the bone, bone marrow, and blood for cancer.
Some of these tests may also be performed after the diagnosis is made to determine the extent of cancer and whether it has spread (metastasized). Once these tests have been performed, the cancer is given a stage, 1 through 4, depending on how extensive it is:
- Stage 1 is the least invasive stage and carries the lowest risk. The tumor in stage 1 is confined to one area.
- Stage 2 is divided into stage 2A and stage 2B. In stage 2A, the primary tumor is confined to one area but cannot be removed completely by surgery. In stage 2B, the primary tumor is confined to one area and may or may not be removed completely by surgery, but cancer cells are found in nearby lymph nodes.
- Stage 3, a stage in which the cancer has spread more extensively than in stage 2, often to areas on the opposite side of the body.
- Stage 4 is the most invasive (highest risk) stage and means that the cancer has spread to distant lymph nodes or other parts of the body. A substage of stage 4 is stage 4S, which consists of a neuroblastoma in a child younger than 1 year in whom the cancer has spread to other parts of the body, the primary tumor is confined to one area and may or may not be removed completely by surgery, and cancer cells may be found in nearby lymph nodes.
Any stage tumor with a genetic characteristic called the n-myc amplification is considered to be high risk (n-myc is a gene that turns on cell growth).