After adult soft tissue sarcoma has been diagnosed, tests are done to find out if cancer cells have spread within the soft tissue or to other parts of the body.

The process used to find out if cancer has spread within the soft tissue or to other parts of the body is called staging. Staging of soft tissue sarcoma is also based on the grade and size of the tumor, whether it is superficial (close to the skin's surface) or deep, and whether it has spread to the lymph nodes or other parts of the body. The information gathered from the staging process determines the stage of the disease. It is important to know the stage in order to plan treatment.

The following tests and procedures may be used in the staging process:

• 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.

• Chest x-ray : An x-ray of the organs and bones inside the chest. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.

• 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.

• Complete blood count (CBC): A procedure in which a sample of blood is drawn and checked for the following:
  • The number of red blood cells, white blood cells, and platelets.
  • The amount of hemoglobin (the protein that carries oxygen) in the red blood cells.
  • The portion of the blood sample made up of red blood cells.

• CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside of the body, such as the lung and abdomen, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.

• MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body. This procedure is also called nuclear magnetic resonance imaging (NMRI).

• 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.

The results of these tests are viewed together with the results of the tumor biopsy to find out the stage of the soft tissue sarcoma before treatment is given. Sometimes chemotherapy or radiation therapy is given as the initial treatment and afterwards the soft tissue sarcoma is staged again.

There are three ways that cancer spreads in the body.

The three ways that cancer spreads in the body are:

• Through tissue. Cancer invades the surrounding normal tissue.
• Through the lymph system. Cancer invades the lymph system and travels through the lymph vessels to other places in the body.
• Through the blood. Cancer invades the veins and capillaries and travels through the blood to other places in the body.

When cancer cells break away from the primary (original) tumor and travel through the lymph or blood to other places in the body, another (secondary) tumor may form. This process is called metastasis. The secondary (metastatic) tumor is the same type of cancer as the primary tumor. For example, if breast cancer spreads to the bones, the cancer cells in the bones are actually breast cancer cells. The disease is metastatic breast cancer, not bone cancer.

The following stages are used for adult soft tissue sarcoma:

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Pea, peanut, walnut, and lime show tumor sizes.

Stage I

Stage I is divided into stages IA and IB:

• In stage IA, the tumor is low-grade (likely to grow and spread slowly) and 5 centimeters or smaller. It may be either superficial (in subcutaneous tissue with no spread into connective tissue or muscle below) or deep (in the muscle and may be in connective or subcutaneous tissue).
• In stage IB, the tumor is low-grade (likely to grow and spread slowly) and larger than 5 centimeters. It may be either superficial (in subcutaneous tissue with no spread into connective tissue or muscle below) or deep (in the muscle and may be in connective or subcutaneous tissue).

Stage II

Stage II is divided into stages IIA and IIB:

• In stage IIA, the tumor is mid-grade (somewhat likely to grow and spread quickly) or high-grade (likely to grow and spread quickly) and 5 centimeters or smaller. It may be either superficial (in subcutaneous tissue with no spread into connective tissue or muscle below) or deep (in the muscle and may be in connective or subcutaneous tissue).
• In stage IIB, the tumor is mid-grade (somewhat likely to grow and spread quickly) and larger than 5 centimeters. It may be either superficial (in subcutaneous tissue with no spread into connective tissue or muscle below) or deep (in the muscle and may be in connective or subcutaneous tissue).

Stage III

In stage III, the tumor is either:

• high-grade (likely to grow and spread quickly), larger than 5 centimeters, and either superficial (in subcutaneous tissue with no spread into connective tissue or muscle below) or deep (in the muscle and may be in connective or subcutaneous tissue); or
• any grade, any size, and has spread to nearby lymph nodes.

Stage III cancer that has spread to the lymph nodes is advanced stage III.

Stage IV

In stage IV, the tumor is any grade, any size, and may have spread to nearby lymph nodes. Cancer has spread to distant parts of the body, such as the lungs.