Adult soft tissue sarcoma (STS) is a disease in which malignant (cancer) cells form in the soft tissues of the body. Soft tissues include the muscles, tendons, fat, blood and lymph vessels, nerves and tissues that the surround the nerves. Soft tissue sarcomas can form almost anywhere in the body, but are most common in the head, neck, arms, legs, trunk, and abdomen.
Soft tissue sarcomas are relatively uncommon and account for approximately one percent of all cancers. These cancers when detected early are usually treated with surgery and radiation therapy. Historically insensitive to chemotherapy, new drugs have recently been discovered that are more active and are now approved for the treatment of STS.1,2
It is important to have accurate pre-treatment evaluation to determine the exact extent of tumor spread. Fully functional limb preservation without amputation is the main goal of treatment. Since soft tissue sarcomas are rare it is important that patients receive treatment in specialized centers with experience and treatment protocols. Treatment requires a multidisciplinary approach with involvement of surgeons, radiation oncologists, medical oncologists, nurse specialists and rehabilitation experts.
The cells of each type of STS look different under a microscope and each STS is named according to which tissue the cancer developed.
Types of Soft Tissue Sarcoma (Adult and Childhood):
- Alveolar Soft-part Sarcoma
- Dermatofibrosarcoma Protuberans
- Epithelioid Sarcoma
- Malignant Fibrous Histiocytoma
- Malignant Hemangiopericytoma
- Malignant Mesenchymoma, Malignant Schwannoma (Malignant Peripheral Nerve Sheath Tumor)
- Non-Bone Osteosarcoma
- Peripheral Neuroectodermal Tumors
- Synovial Sarcoma
- Unidentifiable Sarcoma
Risk factors for developing a STS include past treatment with radiation, exposure to certain chemicals such as Thorotrast (thorium dioxide), vinyl chloride or arsenic. For more information on conditions associated with STS go to: Screening and Prevention of Soft Tissue Sarcoma
The suspicion of a STS often first arises when a lump or swelling in soft tissue of the body is detected. In order to diagnose the cause of the lump a physician will perform a biopsy. A biopsy can be performed on an outpatient basis. During a biopsy, a physician removes the lump or some cells adjacent lymph nodes and other suspicious areas for examination by a laboratory pathologist to determine the presence and aggressiveness of cancer if it is present. Because STS can be hard to diagnose patients should ask to have tissue samples checked by a pathologist who has experience in diagnosing STS.
When cancer is identified in the biopsy specimen, several other tests may be performed on the specimen in order to further classify the cancer and determine the optimal treatment strategy. Based on the stage of the cancer and the results of these tests, treatment of STS is personalized for each individual. Treatment may involve surgery, radiation therapy, chemotherapy, or targeted therapy.
Stage: Stage is a measure of the extent of the cancer, and is based on the size of the tumor and the presence or absence of lymph node metastases and distant metastases. Determining the stage of the cancer may require a number of procedures, such as blood tests, chest x-rays, mammography, computed tomography (CT), or magnetic resonance imaging (MRI).
Stage I is divided into stages IA and IB:
- Stage IA cancers are low grade, less than 5 centimeters in size and have not spread to adjacent lymph nodes.
- Stage IB: Stage IA cancers are low grade, greater than 5 centimeters in size and have not spread to adjacent lymph nodes.
Stage II is divided into stages IIA and IIB:
- Stage IIA cancers are mod or high grade, less than 5 centimeters in size and have not spread to adjacent lymph nodes.
- Stage IIB: Stage IIB cancers are mid or high grade, greater than 5 centimeters in size and have not spread to adjacent lymph nodes.
Stage III soft tissue sarcomas are either high grade, larger than 5 or have spread to nearby lymph nodes. Stage III STS that have spread to lymph nodes are often called “advanced STS”
Stage IV: The sarcoma has spread to distant locations in the body, which may include the liver, lungs, bones or other sites.
Recurrent/Relapsed: The cancer has progressed or returned (recurred/relapsed) following an initial treatment.
1 FDA approves Votrient for advanced soft tissue sarcoma [FDA News Release]. U.S. Food and Drug Administration website. Available at: http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm302065.htm
2 United States Food and Drug Administration. FDA approves first drug to show survival benefit in liposarcoma. Available at: http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm483714.htm. Accessed January 28, 2016