Causes and Diagnoses

Causes and Diagnoses of Sarcoma

The exact cause of sarcoma is unknown, but certain factors can increase your risk of developing these types of cancers.

Risk factors of soft tissue sarcoma include:

  • Exposure to radiation to treat other cancers, such as breast or cervical cancer
  • A damaged lymph system or lymphedema
  • Exposure to certain chemicals, particularly herbicides, dioxin and chlorophenols (wood preservative)
  • Family history of illnesses such as:
    • Neurofibromatosis
    • Li-Fraumeni syndrome
    • Retinoblastoma

Risk factors for osteosarcoma include:

  • Growth spurts in teens or young adults
  • Being male
  • Past treatment with radiation therapy
  • Past treatment with anticancer drugs called alkylating agents
  • Having a certain change in the retinoblastoma gene
  • Having certain conditions such as:
  • Hereditary retinoblastoma
  • Li-Fraumeni syndrome
  • Rothmund-Thomson syndrome
  • Paget disease


To diagnose sarcomas your physician will need to perform a variety of diagnostic testing, including a complete physical exam. If there is a lump, the physician will look at its size and shape, and the effect it has had on surrounding areas.

To diagnose soft tissue sarcoma, your physician will need to perform a surgical biopsy. A biopsy is a procedure that removes tissue from the tumor to be analyzed under a microscope.

To diagnose osteosarcoma or Ewing sarcoma, one or more of diagnostic tests may be used, including:

  • X-ray: This is often the first test done if your physician suspects a bone tumor, as most Ewing tumors can be diagnosed with an X-ray
  • Computed tomography scan (CT scan): A CT scan can help your physician identify a Ewing tumor more clearly. A CT scanner takes X-rays of your body from different angles as you slide through it on a table. A computer combines these pictures to produce a more detailed picture of the inside of your body
  • Magnetic resonance imaging (MRI): During an MRI, large magnets and radio waves produce detailed cross-sectional pictures that look like slices of your body. These pictures will also help your physician see what part of a lump to take out in a biopsy
  • Bone scan: For this test, a nurse or technician injects you with radioactive dye, then takes pictures of your bones with a special camera about two hours later. The picture shows areas of bone where the radiation is concentrated, which can mean that there is an abnormality. Your physician may use this test to find out if a bone tumor has spread to other bones or if a soft tissue tumor has spread to bone
  • Positron emission tomography (PET) scan: A slightly radioactive sugar is injected into the blood during a PET scan. Tumors use more of this sugar than normal cells, so the radiation collects in tumors, where it can be seen with a special camera. PET scans can help determine the spread of Ewing tumors, find out if abnormal areas seen on a bone scan or CT scan are tumors, and help follow the response of the tumor to treatment
  • Biopsy: In nearly all cases, the physician will remove a sample of tissue from your tumor to confirm the diagnosis. A pathologist will look at the sample under a microscope to verify whether or not the tumor is cancerous. If there is a chance that a tumor is a Ewing tumor, it is very important that the biopsy be done by a physician with experience in treating this disease. There are several types of biopsy:
    • Excisional biopsy: If your tumor is small, a surgeon can cut through your skin and take out the whole tumor. You will be given anesthesia so that you are asleep during the biopsy
    • Incisional biopsy: If your tumor is large, the surgeon removes only a small part of the tumor. If the tumor is close to your skin's surface, the surgeon may numb the area. If the tumor is deep inside your body, you will be given anesthesia to put you to sleep
    • Needle biopsy: Your physician inserts a thin, hollow needle through your skin to remove tiny bits of tissue from the tumor. This type of biopsy does not require surgery, and you are awake during this test. The physician may use a CT scan to guide the needle. This can eliminate other reasons for the growth, such as infection
    • Bone marrow biopsy: This test may be conducted once the diagnosis is made to help determine if the cancer has spread to the bone marrow. For this test, hollow needles are used to remove samples of bone marrow, usually from the back of the hip bones. Teens and adults may be awake when this is done (with the area numbed), but children are usually sedated for this procedure