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Unusual Cancers of Childhood (PDQ®)

Patient Version
Last Modified: 07/29/2014

General Information About Unusual Cancers of Childhood



Unusual cancers of childhood are cancers rarely seen in children.

Cancer in children and teenagers is rare. Since 1975, the number of new cases of childhood cancer has slowly increased. Since 1975, the number of deaths from childhood cancer has decreased by more than half.

Unusual cancers are so rare that most children's hospitals might see less than a handful of some types in several years. Because the unusual cancers are so rare, there is not a lot of information about what treatment works best. A child's treatment is often based on what has been learned from treating other children. Sometimes, information is available only from reports of the diagnosis, treatment, and follow-up of one child or a small group of children who were given the same type of treatment.

Many different cancers are covered in this summary. They are grouped by where they are found in the body.

Tests are used to detect (find), diagnose, and stage unusual cancers of childhood.

Tests are done to detect, diagnose, and stage cancer. The tests used depend on the type of cancer. After cancer is diagnosed, tests are done to find out if cancer cells have spread from where the cancer began to other parts of the body. The process used to find out if cancer cells have spread to other parts of the body is called staging. The information gathered from the staging process determines the stage of the disease. It is important to know the stage in order to plan the best treatment. The following tests and procedures may be used to detect, diagnose, and stage cancer:

  • Physical exam and history : An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.

  • Blood chemistry studies : A procedure in which a blood sample is checked to measure the amounts of certain substances released into the blood by organs and tissues in the body. An unusual (higher or lower than normal) amount of a substance can be a sign of disease in the organ or tissue that makes it.

  • Biopsy : The removal of cells or tissues so they can be viewed under a microscope by a pathologist to check for signs of cancer. There are many different types of biopsy procedures. The most common types include the following:

  • X-ray : An x-ray is a type of energy beam that can go through the body and onto film.

  • CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. The pictures are made by a computer linked to an x-ray machine. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.
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    Computed tomography (CT) scan of the abdomen; drawing shows the patient on a table that slides through the CT machine, which takes x-ray pictures of the inside of the body.
    Computed tomography (CT) scan of the abdomen. The patient lies on a table that slides through the CT machine, which takes x-ray pictures of the inside of the body.

  • PET scan (positron emission tomography scan): A procedure to find malignant tumor cells in the body. A small amount of radioactive glucose (sugar) is injected into a vein. The PET scanner rotates around the body and makes a picture of where glucose is being used in the body. Malignant tumor cells show up brighter in the picture because they are more active and take up more glucose than normal cells do.

  • MRI (magnetic resonance imaging): A procedure that uses a magnet and radio waves to make a series of detailed pictures of areas inside the body. The pictures are made by a computer. This procedure is also called nuclear magnetic resonance imaging (NMRI).
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    Magnetic resonance imaging (MRI) of the abdomen; drawing shows the patient on a table that slides into the MRI machine, which takes pictures of the inside of the body. The pad on the patient’s abdomen helps make the pictures clearer.
    Magnetic resonance imaging (MRI) of the abdomen. The patient lies on a table that slides into the MRI machine, which takes pictures of the inside of the body. The pad on the patient’s abdomen helps make the pictures clearer.

  • Ultrasound exam: A procedure in which high-energy sound waves (ultrasound) are bounced off internal tissues or organs and make echoes. The echoes form a picture of body tissues called a sonogram. The picture can be printed to be looked at later.
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    Abdominal ultrasound; drawing shows a woman on an exam table during an abdominal ultrasound procedure. A diagnostic sonographer (a person trained to perform ultrasound procedures) is shown passing a transducer (a device that makes sound waves that bounce off tissues inside the body) over the surface of the patient’s abdomen. A computer screen shows a sonogram (computer picture).
    Abdominal ultrasound. An ultrasound transducer connected to a computer is passed over the surface of the abdomen. The ultrasound transducer bounces sound waves off internal organs and tissues to make echoes that form a sonogram (computer picture).

  • Endoscopy : A procedure to look at organs and tissues inside the body to check for abnormal areas. An endoscope is inserted through an incision (cut) in the skin or opening in the body, such as the mouth or rectum. An endoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove tissue or lymph node samples, which are checked under a microscope for signs of disease.
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    Upper endoscopy; shows endoscope inserted through the mouth and esophagus and into the stomach. Inset shows patient on table having an upper endoscopy.
    Upper endoscopy. A thin, lighted tube is inserted through the mouth to look for abnormal areas in the esophagus, stomach, and first part of the small intestine.

  • Bone scan : A procedure to check if there are rapidly dividing cells, such as cancer cells, in the bone. A very small amount of radioactive material is injected into a vein and travels through the bloodstream. The radioactive material collects in the bones and is detected by a scanner.
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    Bone scan; drawing shows patient lying on a table that slides under the scanner, a technician operating the scanner, and a monitor that will show images made during the scan.
    Bone scan. A small amount of radioactive material is injected into the patient's bloodstream and collects in abnormal cells in the bones. As the patient lies on a table that slides under the scanner, the radioactive material is detected and images are made on a computer screen or film.

There are three ways that cancer spreads in the body.

Cancer can spread through tissue, the lymph system, and the blood:

  • Tissue. The cancer spreads from where it began by growing into nearby areas.
  • Lymph system. The cancer spreads from where it began by getting into the lymph system. The cancer travels through the lymph vessels to other parts of the body.
  • Blood. The cancer spreads from where it began by getting into the blood. The cancer travels through the blood vessels to other parts of the body.

Cancer may spread from where it began to other parts of the body.

When cancer spreads to another part of the body, it is called metastasis. Cancer cells break away from where they began (the primary tumor) and travel through the lymph system or blood.

  • Lymph system. The cancer gets into the lymph system, travels through the lymph vessels, and forms a tumor (metastatic tumor) in another part of the body.
  • Blood. The cancer gets into the blood, travels through the blood vessels, and forms a tumor (metastatic tumor) in another part of the body.

The metastatic tumor is the same type of cancer as the primary tumor. For example, if thyroid cancer spreads to the lung, the cancer cells in the lung are actually thyroid cancer cells. The disease is metastatic thyroid cancer, not lung cancer.