Soft tissue sarcoma, sometimes abbreviated as STS, is cancer that forms in the soft tissues of the body, such as the muscles, tendons, fat, nerves, connective tissues and blood vessels.
Because there are many different subtypes of soft tissue sarcomas, diagnosing the specific type of STS can be a challenge for healthcare providers. Diagnosis typically involves a biopsy, where a tissue sample is taken from a tumor or tumors and tested in a lab.
About one in three patients are diagnosed with an uncertain type of STS—where healthcare providers know that the cancer is a form of STS, but cannot pinpoint the exact subtype. This makes undifferentiated/unclassified soft tissue sarcoma the most common form of STS.
Other common subtypes are:
- Undifferentiated pleomorphic sarcoma (UPS), a type of sarcoma that can form in both soft tissue and bone. UPS most often starts in the legs, arms or the rear of the abdomen. This type of sarcoma can grow quickly and spread to other areas of the body, including the lungs.
- Liposarcoma, a type of sarcoma that begins in adipose tissue (fat tissue). This is the most common form of soft tissue sarcoma in adults.
- Leiomyosarcoma, a type of sarcoma that can begin in any part of the body where there is a vein. (It is important to note that leiomyosarcomas are different than leiomyomas, which are benign uterine fibroids; uterine fibroids are not a precursor to leiomyosarcomas.)
- Gastrointestinal stromal tumor (GIST), a type of sarcoma that begins in the gastrointestinal tract. The stomach is the most common location.
- Synovial sarcoma, a type of sarcoma that begins in or around the joints. This most often occurs in the hip, knee, ankle or shoulder joints, though it can occur in any location in the body.
- Myxofibrosarcoma, a type of sarcoma that begins in the connective tissues that separate muscles from other muscles, and muscles from skin.
As with other forms of cancer, treatment for soft tissue sarcoma depends on a number of factors about both the cancer and the patient. These include, but are not limited to, the type of soft tissue sarcoma, the stage of the cancer, the locations of the tumors, the grade of the tumors, the overall health of the patient and the patient’s medical history. Surgery to remove the tumor or tumors is the most common form of treatment, though radiation therapy and chemotherapy are also used, often in combination with surgery. Targeted therapy drugs may also be options for some types of soft tissue sarcoma.
