This is a medical question of type : stages 
 What are the stages of Childhood Soft Tissue Sarcoma ? 
 Key Points
                    - After childhood soft tissue sarcoma has been diagnosed, tests are done to find out if cancer cells have spread to other parts of the body.     - There are three ways that cancer spreads in the body.    - Cancer may spread from where it began to other parts of the body.
                
                
                    After childhood soft tissue sarcoma has been diagnosed, tests are done to find out if cancer cells have spread 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. There is no standard staging system for childhood soft tissue sarcoma.    In order to plan treatment, it is important to know the type of soft tissue sarcoma, whether the tumor can be removed by surgery, and whether cancer has spread to other parts of the body.   The following procedures may be used to find out if cancer has spread:         -   Sentinel lymph node biopsy: A sentinel lymph node biopsy is done to check if cancer has spread to the lymph nodes. The sentinel lymph node is the first lymph node to receive lymphatic drainage from a tumor. It is the first lymph node the cancer is likely to spread to from the tumor. A small amount of a radioactive substance and/or blue dye is injected near the tumor. The radioactive substance or dye flows through the lymph ducts to the lymph nodes. The first lymph node to receive the substance or dye is removed. A pathologist views the tissue under a microscope to look for cancer cells. If cancer cells are not found, it may not be necessary to remove more lymph nodes. This procedure is used for epithelioid and clear cell sarcoma.     -   PET scan: A PET scan is 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. This procedure is also called positron emission tomography (PET) scan.    -   PET-CT scan: A procedure that combines the pictures from a PET scan and a computed tomography (CT) scan. The PET and CT scans are done at the same time on the same machine. The pictures from both scans are combined to make a more detailed picture than either test would make by itself.
                
                
                    There are three ways that cancer spreads in the body.
                    Cancer can spread through tissue, the lymph system, and the blood:         - Tissue. The cancer spreads from where it began by growing into nearby areas.     - Lymph system. The cancer spreads from where it began by getting into the lymph system. The cancer travels through the lymph vessels to other parts of the body.     - Blood. The cancer spreads from where it began by getting into the blood. The cancer travels through the blood vessels to other parts of the body.
                
                
                    Cancer may spread from where it began to other parts of the body.
                    When cancer spreads to another part of the body, it is called metastasis. Cancer cells break away from where they began (the primary tumor) and travel through the lymph system or blood.         - Lymph system. The cancer gets into the lymph system, travels through the lymph vessels, and forms a tumor (metastatic tumor) in another part of the body.    - Blood. The cancer gets into the blood, travels through the blood vessels, and forms a tumor (metastatic tumor) in another part of the body.        The metastatic tumor is the same type of cancer as the primary tumor. For example, if soft tissue sarcoma spreads to the lung, the cancer cells in the lung are soft tissue sarcoma cells. The disease is metastatic soft tissue sarcoma, not lung cancer.