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. For example, imaging tests, such as an x-ray, may be used to diagnose bone sarcoma and to find out whether the cancer has spread. Imaging tests show pictures of the inside of the body. Benign and cancerous tumors usually look different on imaging tests, which are described below.

Although imaging tests may suggest a diagnosis of bone sarcoma, a biopsy will be performed whenever possible to confirm the diagnosis and to find out the subtype. Because sarcomas are rare and the way a biopsy is performed can affect the outcomes of surgery and risk of recurrence, it is important for the biopsy to be performed by a specialist any time a bone sarcoma is suspected. 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. It is extremely important for a patient to see a surgeon who specializes in sarcomas, such as an orthopedic oncologist, before any surgery or a biopsy is performed.

How bone sarcoma is diagnosed

There are many tests used for diagnosing bone sarcoma. Not all tests described here will be used for every person. Your doctor may consider these factors when choosing a diagnostic test:

• The type of cancer suspected

• Your signs and symptoms

• Your age and general health

• The results of earlier medical tests

In addition to a physical examination, the following tests may be used to diagnose or determine the stage (or extent) of a bone sarcoma:

• Blood tests. Sarcomas are never diagnosed by a laboratory blood test. People with osteosarcoma or Ewing sarcoma can occasionally have higher alkaline phosphatase and lactate dehydregenase levels in the blood, but high levels of these substances may also have any of a number of benign causes, such as growing in children or a healing broken bone.

• X-ray. An x-ray is a way to create a picture of the structures inside of the body using a small amount of radiation.

• Bone scan. A bone scan may be used to help determine the stage of a bone sarcoma. 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 cancerous cells or sometimes a broken bone, stand out on the image.

• 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. 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. MRI scans are used to check for any tumors in nearby soft tissue. MRIs provide a road map for the orthopedic oncology surgeon to perform the best cancer surgery possible.

• Positron emission tomography (PET) or PET-CT scan. A PET scan may be used to help determine the stage of a bone sarcoma. A PET scan is usually combined with a CT scan (see above), called a PET-CT scan. However, you may hear your doctor refer to this procedure just as a PET scan. A PET scan is a way to create picture 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.

• 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. A pathologist then analyzes the sample(s). A pathologist is a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease. Whether a needle biopsy or incisional biopsy is performed depends on where the cancer is located. During a needle biopsy, a small hole is made in the bone, and a tissue sample is removed from the tumor with a needle-like instrument. During an incisional biopsy, the tissue sample is removed after a small cut is made in the tumor. Sometimes it may not be possible to do a biopsy.

  The type of biopsy and how it is done are important in diagnosing and treating sarcoma, so patients should be seen in a sarcoma specialty center even before the biopsy is performed. At the sarcoma center, the treating surgeon can identify the location for the biopsy. Because bone sarcomas are uncommon, it is also important to have an expert pathologist review the sample of tissue removed to appropriately diagnose a sarcoma.

After diagnostic tests are done, your doctor will review the results with you. If the diagnosis is cancer, these results also help the doctor describe the cancer. This is called staging and grading.

The next section in this guide is Stages and Grades. 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.