Diagnosis

Doctors use many tests to diagnose cancer and determine if it has metastasized (spread). Some tests may also determine which treatments may be the most effective. For most types of cancer, including sarcoma, 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. Imaging tests may be used to find out whether the cancer has metastasized. Your doctor may consider these factors when choosing a diagnostic test:

• Age and medical condition
  
  
• The type of cancer suspected
  
  
• Severity of symptoms
  
  
• Previous test results

There are no standard screening tests for sarcoma. A doctor should examine any unusual or new lumps or bumps that are growing to make sure it is not cancer. Sarcoma is rare. This makes it important to consult a doctor who has experience with this type of cancer as soon as there is a possibility that it might be sarcoma.

A diagnosis of sarcoma is made by a combination of clinical examination and imaging tests. It is confirmed by the results of a biopsy, a procedure in which a small amount of tissue is removed for examination under a microscope.

In addition to a physical examination, the following tests may be used to diagnose sarcoma:

Imaging tests

A benign (noncancerous) and malignant (cancerous) tumor may look different on imaging tests. In general, a benign tumor has round, smooth, well-defined borders. A malignant tumor has irregular, poorly defined margins due to its aggressive growth.

X-ray. An x-ray is a picture of the inside of the body. For instance, a chest x-ray can help doctors determine if the cancer has spread to the lungs. Typically, if an x-ray suggests cancer, the doctor will order other imaging tests. X-ray is particularly useful for bone sarcomas.

Ultrasound. An ultrasound uses sound waves to create a picture of the internal organs.

Computed tomography (CT or CAT) scan. A CT scan creates a three-dimensional picture of the inside of the body with an x-ray machine. A computer then combines these images into a detailed, cross-sectional view that shows any abnormalities or tumors. Sometimes, a contrast medium (a special dye) is injected into a patient’s vein to provide better detail.

Magnetic resonance imaging (MRI). An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. A contrast medium may be injected into a patient’s vein to create a clearer picture. MRI scans are useful to check for tumors in soft tissues nearby.

Positron emission tomography (PET) scan. A PET scan is a way to create pictures of organs and tissues inside the body. A small amount of a radioactive substance is injected into a patient’s body and absorbed by the organs or tissues being studied. This substance gives off energy that is detected by a scanner, which produces the images.

Integrated PET-CT scan. This scanning method collects images both from CT and PET scans at the same time, and then combines the images. This technique has the advantage of looking at both the structure and metabolism of the tumor and normal tissues. This information can be helpful in treatment planning and evaluating treatment benefit.

Imaging tests may suggest the diagnosis of sarcoma, but a biopsy will always be performed to confirm the diagnosis and determine the subtype. It is vitally important for a patient to be seen by a sarcoma specialist before any surgery or biopsy is performed.

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. The sample removed from the biopsy is analyzed by a pathologist (a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease). For a needle biopsy (usually a core needle biopsy, less often a thin needle biopsy), a doctor removes a small sample of tissue from the tumor with a needle-like instrument. This may be performed with the help of ultrasound, CT scan, or MRI to precisely locate the site of the tumor. In an incisional biopsy, the surgeon cuts into the tumor and removes a sample of tissue. In an excisional biopsy, the surgeon removes the entire tumor. Because these tumors are uncommon, it is important that the biopsy is reviewed by an expert pathologist to appropriately diagnose a sarcoma.

Learn more about what to expect when having common tests, procedures, and scans.

Find out more about common terms used during a diagnosis of cancer.