Definition of soft tissue sarcoma: A cancer that begins in the muscle, fat, fibrous tissue, blood vessels, or other supporting tissue of the body.

Sarcomas are a diverse and relatively rare group of malignant tumors that develop in soft tissue and bone. Soft tissue sarcomas form in cartilage, fat, muscle, fibrous tissue, blood vessels, and other connective or supportive tissues of the body; osteosarcomas develop in bone; liposarcomas form in fat; rhabdomyosarcomas form in muscle; and Ewing sarcomas form in bone and soft tissue. Sarcomas can be difficult to distinguish from other malignancies when they are found within organs; thus, their incidence is probably underestimated. Soft tissue sarcomas are more common than bone sarcomas. There are several subtypes of both soft tissue sarcoma and bone sarcoma, but the exact number of Americans with each sarcoma subtype is unknown. The 5-year relative survival rate for both bone and soft tissue sarcoma is approximately 65 percent.

Certain inherited disorders and past treatment with radiation therapy can increase the risk of soft tissue sarcoma and some bone sarcomas.  Standard treatments for bone and soft tissue sarcoma include surgery, chemotherapy, and radiation therapy. In addition to those treatments, patients with bone sarcoma and uterine sarcoma may receive samarium 153 and hormone therapy, respectively.

The following stages are used for adult soft tissue sarcoma:

Stage I

Stage I is divided into stages IA and IB:

Stage II

Stage II is divided into stages IIA and IIB:

Stage III

In stage III, the tumor is either:

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 nodesCancer has spread to distant parts of the body, such as the lungs.

All information was taken from the NCI (National Cancer Institute)