Soft Tissue Sarcoma

Soft tissue sarcoma is a disease in which cancer cells are found in soft tissue in the body.  Soft tissue includes muscles, tendons, connective tissues, fat, blood vessels, nerves, and synovial (joint) tissues.  There are many types of soft tissue sarcoma.  The term soft tissue is used to distinguish these sarcomas from bone sarcomas.

The types of tumor that can develop from different soft tissues include:

• Tumors of Fat Tissue – Lipomas (the most common benign soft tissue tumor); liposarcomas
• Tumors of Muscle Tissue (smooth muscle and skeletal muscle) – leiomyomas; leiomyosarcomas; Rhabdomyomas; Rhabdomyosarcomas
• Tumors of Peripheral Nerve Tissue – Neurofibromas; malignant schwannomas
• Tumors of Joint Tissue (tumors of joints start in the synovium) – Nodular tenosynovitis; synovial sarcoma
• Tumors of Blood Vessels and Lymph Vessels – Hemangiomas; lymphangiomas; angiosarcomas; Kaposi's sarcoma; hemangioendothelioma
• Tumor of Perivascular Tissue – Glomus tumors; hemangiopericytoma
• Tumors of Fibrous Tissue – Fibromas; fibrosarcoma; desmoid tumor; dermatofibrosarcoma protuberans; malignant fibrous histiocytoma
• Tumors of Uncertain Tissue Type – Myxoma; malignant mesenchymoma; alveolar soft-part sarcoma; epithelioid sarcoma; clear cell sarcoma; desmoplastic small cell tumor.

Incidence; Causes and Development; Contributing Risk Factors

Soft tissue sarcomas are relatively uncommon.  Although they may be found in children, soft tissue sarcomas are more common in adults.

They can develop in any part of the body.  Half of them develop in the arms or legs.  The rest arise in the trunk, head and neck area, internal organs, or the retroperitoneum (the back of the abdominal cavity).

Risk factors include the following:

• Exposure to certain types of chemicals, such as herbicides, wood preservatives, polycyclic hydrocarbons, dioxin
• Exposure to ionizing radiation, including therapeutic, diagnostic, and accidental.  This risk factor accounts for under 5% of sarcomas.  The most common cause of radiation exposure in patients who develop sarcomas is from radiation given to treat other tumors, such as breast cancer or lymphoma.  The average time between radiation exposure and diagnosis of a sarcoma is about 10 years.
• A history of angiosarcoma of the liver
• A weak or poorly-functioning immune system

• Inherited diseases such as:

  • Neurofibromatosis – a disease that usually runs in families and is characterized by many neurofibromas (benign tumors that form in nerves under the skin and in other parts of the body).  One or more neurofibromas will develop into a malignant peripheral nerve sheath tumor in about 5% of people with neurofibromatosis.
  • Gardner's syndrome – a disease that runs in families and leads to benign polyps (precancerous growths) and cancers in the intestines.  It also causes desmoid tumors (a type of low-grade fibrosarcoma) in the abdomen and benign bone tumors.
  • Li-Fraumeni syndrome, which runs in families and increases the risk of developing breast cancer, brain tumors, leukemias, and cancer of the adrenal glands.  People with Li-Fraumeni syndrome also have an increased risk of developing soft tissue sarcomas and bone sarcomas.  If their cancer is treated with radiation, they have a very high chance of developing a new cancer in the part of the body that received the radiation.
  • Retinoblastoma – an eye cancer of children that can be hereditary.  Children with the inherited form of retinoblastoma also have an increased risk of developing bone or soft tissue sarcomas.
• Damaged lymph nodes: Lymph (a clear fluid containing immune system cells) is transported throughout the body by lymph vessels and filtered by lymph nodes.  Lymphangiosarcomas, a cancer of lymph vessels, can develop in parts of the body where lymph nodes have been removed by surgery or damaged by radiation therapy.  Although this is a rare complication, it affects some women whose axillary lymph nodes were removed and who received radiation to treat their breast cancer.

Signs and Symptoms

In the early stages, a sarcoma is small and does not produce symptoms.  As the tumor grows, it may push aside normal body structures, causing symptoms.

The most common symptom of a sarcoma is a lump or swelling that may or may not be painful.  Symptoms vary, depending on the part of the body that is affected.  For example, tumors found in the following areas of the body may develop these symptoms:

• Arm or leg – uncomfortable swelling in the affected limb
• Lung – cough and breathlessness
• Bowel – abdominal pain, vomiting, and constipation
• Uterus – bleeding from the vagina and pain in the pelvis or lower abdomen.

Diagnosis and Tests

The doctor may decide to order an X-ray or other tests if a tumor is suspected.  However, the only way to confirm the diagnosis is with a biopsy.  If a sarcoma is found, staging tests are performed to find out if the cancer has spread and, if so, to what extent.

Treatment and Prevention

Treatment depends on the stage of the cancer.  Conventional treatments may include:

• Surgery – surgical removal of the cancerous tumor and nearby tissues, and possibly nearby lymph nodes.

• Radiation Therapy (Radiotherapy) – the use of radiation to kill cancer cells and shrink tumors.  When a sarcoma is aggressive looking, and the surgeon has completed his or her task of removing as much of it as possible, adding radiation will significantly reduce the chances of the cancer coming back.  Radiation may be:

  • External Radiation Therapy – radiation directed at the tumor from a source outside the body
  • Internal Radiation Therapy – radioactive materials placed into the body near the cancer cells
• Chemotherapy – the use of drugs to kill cancer cells.  Chemotherapy may be given in many forms including: pill, injection, or by catheter.  The drugs enter the bloodstream and travel through the body killing mostly cancer cells, but also some healthy cells.  Chemotherapy is generally reserved for only certain types of sarcomas, such as those found in children (osteosarcoma) or when the sarcoma has spread to other parts of the body (metastatic disease).