Soft tissue sarcoma

What is a soft tissue sarcoma?

Soft tissue sarcoma is a malignant growth (cancer) that develops or appears in any soft tissue part of the body such as, muscles, ligaments, fat and connective tissues. These tumors account for about 8% of all cancers in children under 20 years of age in the United States (approximately 800-900 new cases per year).

What are the types of soft tissue sarcoma?

When the pathologist examines these tumors under a microscope they can often determine what type of tissue that the tumor belongs to.

For example, rhabdomyosarcoma arises from skeletal muscle and is the most common soft tissue sarcoma in children and adolescents. Other types of soft tissue sarcomas are named based on their possible tissue of origin. Examples include: liposarcoma (fat tissue), malignant peripheral nerve sheath (nerve sheath), and leiomyosarcoma (smooth muscle).

In some cases, we are not able to identify the tissue of origin based on how they look under the microscope. Examples include, synovial sarcoma, clear cell sarcoma and alveolar soft part sarcoma.

What kinds of tests are done to evaluate if the tumor has spread?

To investigate exactly where the tumor is and if it has spread to other tissues or organs your doctor will order various blood tests and X-rays and other tests. CAT (computerized axial tomography) scan or MRI (magnetic resonance imaging) are done to see exactly where the tumor is and how big it is. CAT (computerized axial tomography) of the lungs and nuclear whole body bone scan are two standard tests to assess if the tumor has spread to the lungs or the bones, respectively.

Some subtypes have a tendency to spread to the nearby or distant lymph nodes (rhabdomyosarcoma, undifferentiated sarcoma, clear cell sarcoma, epitheloid sarcoma and synovial sarcoma). If you have one of these tumors your doctor may order a procedure called sentinel lymph node biopsy. Patients with rhabdomyosarcoma can have spread of their tumor to the bone marrow; a bone marrow aspiration and biopsy is routinely done in all of these patients.

All of the above tests and procedures are considered standard of care universally. Your doctor may also order an imaging test called a whole body positron emission tomography (PET) scan.

What is the treatment for soft tissue sarcoma?

Once all of these procedures are completed treatment decisions can be made based on the extent of tumor (confined to the place of origin or spread to other organs) and how much tumor is left after initial surgical removal.

For rhabdomyosarcoma, after biopsy of removal of the tumor all patient receive chemotherapy. Some patients will also receive radiation therapy to the primary tumor site. With current treatments about 70% (7 out of 10 children with rhabdomyosarcoma can be cured). All patients with rhabdomyosarcoma at our center are treated in clinical trials that tailor treatment based on the site, spread and type of rhabdomyosarcoma.

For other soft tissue sarcomas, surgery is the main type of treatment to remove tumors. In some patients radiation therapy is used to treat known or unknown residual tumor after initial surgery. Chemotherapy is another method that is used in patients with large tumors that cannot be removed completely with surgery or in patients who have metastatic spread. About 70-80% of children with tumors that are taken out by surgery can be cured. Patients with tumors that have spread (metastases) are much more difficult to treat.