ON THIS PAGE: You will find a list of common tests, procedures, and scans that doctors use to find the cause of a medical problem. Use the menu to see other pages.
Doctors use many tests to find, or diagnose, cancer. They also do tests to learn if cancer has spread to another part of the body from where it started. If the cancer has spread, it is called metastasis. Doctors may also do tests to learn which treatments could work best.
For most types of cancer, a biopsy is the only sure way for the doctor to know if an area of the body has cancer. In a biopsy, the doctor takes a small sample of tissue for testing in a laboratory. If a biopsy is not possible, the doctor may suggest other tests that will help make a diagnosis.
How Ewing sarcoma is diagnosed
There are many tests used for diagnosing Ewing sarcoma. Not all tests described here will be used for every person. The doctor may consider these factors when choosing a diagnostic test:
The type of cancer suspected
Signs and symptoms
Age and general health
The results of earlier medical tests
In addition to a physical examination, the following tests may be used to help diagnose Ewing sarcoma:
- Blood tests. A complete blood count (CBC) is a blood test that counts the number of each type of blood cell. Abnormal levels of white blood cells, red blood cells, and platelets can be a sign that the tumor has spread. The doctor may also check liver and kidney function and look for high levels of a particular blood enzyme called lactate dehydrogenase, or LDH, which sometimes helps signal the presence of a tumor in the body. While a CBC alone cannot make the diagnosis of Ewing sarcoma, it can help doctors to diagnose the disease.
Imaging tests show pictures of the inside of the body. They can show if cancer has spread.
X-ray. An x-ray is a way to create a picture of the organs and tissues inside of the body using a small amount of radiation. Doctors can usually find bone tumors with an x-ray.
Computed tomography (CT or CAT) scan. A CT scan takes pictures of the inside of the body using x-rays taken from different angles. A computer combines these pictures into a detailed, 3-dimensional image that shows any abnormalities or tumors. For Ewing sarcoma, a CT scan of the chest will be done to see if the tumor has spread to the lungs. A CT scan can be used to measure the tumor’s size. Sometimes, a special dye called a contrast medium is given before the scan to provide better detail on the image. This dye can be injected into a patient’s vein or given as a pill or liquid to swallow.
Magnetic resonance imaging (MRI). An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. MRI can be used to measure the tumor’s size. A special dye called a contrast medium is given before the scan to create a clearer picture. This dye can be injected into a patient’s vein or given as a pill or liquid to swallow. MRI is more helpful than a CT scan in revealing where the tumor is in relation to nearby nerves and blood vessels.
Positron emission tomography (PET) or PET-CT scan. A PET scan is usually combined with a CT scan (see above), called a PET-CT scan. However, you may hear the doctor refer to this procedure just as a PET scan. A PET scan is a way to create pictures of organs and tissues inside the body. A small amount of a radioactive sugar substance is injected into the patient’s body. This sugar substance is taken up by cells that use the most energy. Because cancer tends to use energy actively, it absorbs more of the radioactive substance. However, the amount of radiation in the substance is too low to be harmful. A scanner then detects this substance to produce images of the inside of the body. For Ewing sarcoma, an integrated PET-CT scan is often more sensitive than a PET scan alone or a bone scan.
Bone scan. A bone scan uses a radioactive tracer to look at the inside of the bones. The amount of radiation in the tracer is too low to be harmful. The tracer is injected into a patient’s vein. It collects in areas of the bone and is detected by a special camera. Healthy bone appears lighter to the camera, and areas of injury, such as those caused by a tumor, stand out on the image.
Biopsy. A biopsy is the removal of a small amount of tissue for examination under a microscope. If the tumor is in an arm or leg, an orthopedic oncologist or an interventional radiologist who has experience with Ewing sarcoma should perform the biopsy. An orthopedic oncologist is a doctor who specializes in cancers of the musculoskeletal system. An interventional radiologist is a doctor who is trained in both radiology and minimally invasive surgery.
During the procedure, the doctor may take a sample of the tumor, bone marrow (see below), or both. Other tests can suggest that cancer is present, but only a biopsy can make a definite diagnosis. A pathologist then analyzes the sample(s) removed during the biopsy. A pathologist is a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease.
Bone marrow aspiration and biopsy. These 2 procedures are similar and often done at the same time to examine the bone marrow and see if Ewing sarcoma is present. Bone marrow has both a solid and a liquid part. A bone marrow aspiration removes a sample of the fluid with a needle. A bone marrow biopsy is the removal of a small amount of solid tissue using a needle.
A pathologist then analyzes the sample(s). A common site for a bone marrow aspiration and biopsy is the pelvic bone, which is located in the lower back by the hip. Doctors often give a type of medication called anesthesia beforehand to numb the area. Anesthesia is medication that blocks the awareness of pain. Stronger types of anesthesia can also be used to lessen the pain.
Other laboratory tests
Other laboratory tests may be done on the tissue sample(s) removed during a biopsy to learn more about the tumor.
Immunohistochemistry. This test finds out whether there are Ewing sarcoma cells in the tissue sample.
Cytogenetic tests and reverse transcription polymerase chain reaction (RT-PCR). These tests find out if the genetic changes that characterize Ewing sarcoma cells are present in the sample.
Biomarker testing of the tumor. Your child’s doctor may recommend running laboratory tests on a tumor and/or bone marrow sample to identify specific genes, proteins, and other factors unique to the tumor. This may also be called molecular testing of the tumor. Results of these tests can help determine your child’s treatment options.
After diagnostic tests are done, the doctor will review the results with you and your child. If the diagnosis is cancer, these results also help the doctor describe the cancer. This is called staging.
The next section in this guide is Stages. It explains the system doctors use to describe the extent of the disease. Use the menu to choose a different section to read in this guide.