Soft Tissue Sarcomas

Introduction

Soft tissue sarcomas are cancers of the supporting tissues of the body. Soft tissue tumors can occur in muscles, fat, nerves, blood vessels, tendons and other tissues that support, surround or protect body organs and joints. While most of such tumors are benign (i.e. not cancerous) and are not life-threatening, those that are malignant are called soft tissue sarcomas. Approximately 12,000 soft tissue sarcomas are newly-diagnosed each year in the United States. About 40% of soft tissue sarcomas occur in the legs, usually at or above the knee. 15% develop in the hands or arms, 15% in the head or neck and the remaining 30% in the shoulders, chest, abdomen or hips.

It is not clear why some people develop sarcomas, but researchers have been able to identify some common characteristics in groups with high rates of soft tissue sarcoma. Some studies have shown that people exposed to phenoxyacetic acid in herbicides and chlorophenols in wood preservative have increased risk of developing soft tissue sarcoma, and people with certain inherited diseases such as neurofibromatosis have a higher risk of developing soft tissue sarcomas. People exposed to high doses of radiation are also at a greater risk for developing soft tissue sarcoma. Researchers are also studying genetic abnormalities and chromosome mutations as possible causes of soft tissue sarcomas.

In their early stages, soft tissue sarcomas rarely display any symptoms. Because soft tissue is very elastic, tumors can grow quite large before they are felt. The first symptom is usually a painless lump. As the tumor grows and begins to press against nearby nerves and muscles, soreness or pain will be felt. Soft tissue sarcomas can only be diagnosed by a surgical biopsy procedure in which tissue from the tumor is removed for analysis under a microscope. Soft tissue sarcomas are treated using surgery, radiation therapy or chemotherapy. Depending on the size, location, extent and severity of the tumor, a combination of all or some of these treatments may be used. Biological therapy is currently being tested as a treatment in clinical trials. The most common types of soft tissue sarcomas are described below:

Vascular Sarcomas

Vascular sarcomas are so named because they contain many blood vessels. There are different forms of vascular sarcomas, including:

Angiosarcoma

Angiosarcomas account for less than 2% of all sarcomas. This rare malignancy arises from endothelial cells of either lymphatic or vascular origin. When the cell of origin can be identified as lymphatic, the lesion is termed a lymphangiosarcoma; when vascular derivation can be determined, the correct term is hemangiosarcoma. Often, the cell of origin cannot be determined with certainty; hence, the more general term angiosarcoma is used.

Approximately half of these lesions occur in the head and neck. The scalp and face are the most common sites of involvement. Angiosarcomas typically occur in those between 50 and 70 years old, and males are more commonly affected than females by a 3:1 ratio. While most patients are asymptomatic at the time of diagnosis, some have pain or bleeding at the tumor site. Conditions associated with angiosarcoma include long-standing lymphedema and prior irradiation. Exposure to vinyl chloride is associated with angiosarcomas of the liver, but this association has not been reported with head and neck angiosarcomas.

Hemangiopericytoma/Solitary Fibrous Tumor (SFT)

Hemangiopericytoma is a very rare form of a vascular tumor. Approximately 15-30% of hemangiopericytomas occur in the head and neck; the sinonasal tract is the most common site. No sex predilection exists, and 90% of hemangiopericytomas arise in people aged 50-70 years. Approximately 10% of hemangiopericytomas occur in children; hemangiopericytomas tend to have a much more indolent course in this group. No etiologic factors are known. Most pathologists prefer to use the term “SFT”, rather than “hemangiopericytoma.” Complete surgical excision is the treatment of choice for patients with hemangiopericytomas. Compared with other sarcomas of the head and neck, hemangiopericytomas are associated with a better prognosis. Local recurrence rates of 10-50% have been reported; fewer than 20% of patients have local recurrence after surgical excision.

Kaposi’s Sarcoma

Kaposi’s sarcoma typically occurs in the tissues under the skin or in the mucous membranes that line the mouth, nose, and anus. The cancer originates in multiple sites in the mid-dermis (second layer of skin) and extends to the epidermis (outer layer of skin). Some forms of Kaposi’s sarcoma look nodular or plaque-like on the skin. Radiation therapy is usually the treatment for Kaposi’s sarcoma; however, when tumors have spread to the organs, chemotherapy may also be used. Karposi’s sarcoma typically affects three different patient groups:

The first group of affected patients includes older men of Jewish, Italian, or Mediterranean heritage. This type of Kaposi’s sarcoma usually progresses slowly over 10-15 years. Patients commonly develop a bluish lesion on the front of the lower leg, which typically spreads to multiple lesions and can also spread to other organs.

The second group of Kaposi’s sarcoma patients consists of people who have received organ transplants and have a weakened immune system as a result of the immunosuppressive treatment following the transplant.

The third patient group is made up of AIDS patients, whose weakened immune systems make them more susceptible to the disease. Kaposi’s sarcoma in AIDS patients usually spreads quickly and can be found in many parts of the body.

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