Soft tissue sarcomas are malignant tumors that can develop from fat, muscle, nerve, fibrous tissues surrounding joints, blood vessels, or deep skin tissues. They can develop in any part of the body. Around 60% of them develop in the arms or legs, and the rest begin in the trunk (20%), head and neck area (10%), internal organs, or the retroperitoneum -back of the abdominal cavity- (15%), but they rarely cause pain, swelling, or other symptoms. Soft tissue sarcomas are rare; they represent less than 1 percent of all new cancer cases.
Sarcoma is the term used to refer to cancers of these tissues. There are about 50 different types:
- Tumors of Fat Tissue (Liposarcomas)
- Tumors of Muscle Tissue (Leiomyosarcomas, Rhabdomyosarcomas)
- Tumors of Peripheral Nerve Tissue (Malignant schwannomas, neurofibrosarcomas, or neurogenic sarcomas)
- Tumors of Joint Tissue (Synovial sarcoma)
- Tumors of Blood Vessels and Lymph Vessels (Hemangioendothelioma, hemangiosarcoma, angiosarcomas, lymphangiosarcomas)
- Tumors of Fibrous Tissue (Fibrosarcoma, dermatofibrosarcoma protuberans (DFSP), malignant fibrous histiocytoma (MFH)
- Tumors of uncertain tissue type (Malignant mesenchymoma, alveolar soft-part sarcoma, epithelioid sarcoma, clear cell sarcoma, desmoplastic small cell tumor.
- Other Types of Sarcoma
RISK FACTOR
A risk factor is anything that increases your chances of getting a disease such as cancer. Risk factors can be lifestyle-related, environmental, or inherited. Different cancers have different risk factors: unprotected exposure to strong sunlight is a risk factor for skin cancer and smoking is a risk factor for cancers of the lung, larynx, mouth, throat, esophagus, kidneys, bladder, and several other organs.
Scientists have found several risk factors that make a person more likely to develop soft tissue sarcomas:
- Ionizing radiation: this accounts for less than 5% of sarcomas. The most common cause is radiation exposure during radiation administered to treat other tumors. The average time between radiation exposure and diagnosis of a sarcoma is about 10 years.
- Radiation therapy: these techniques have improved steadily over several decades. Treatments now target the cancers more precisely, and more is known about selecting radiation doses. These advances are expected to reduce the number of secondary cancers resulting from radiation therapy.
- Family history: Certain inherited conditions increase a person's risk of developing soft tissue sarcomas, for instance, neurofibromatosis, Gardner syndrome, Li-Fraumeni syndrome or Retinoblastoma.
- Damaged lymph system: in parts of the body where lymph nodes have been removed by surgery or damaged by radiation therapy, lymphangiosarcomas can develop as a rare complication.
- Injury: An injury is not a risk factor for developing sarcomas. However, this issue has been a cause of confusion in the past. One reason is that injury may produce a swelling that resembles a tumor but is not a true tumor. Also, pain from an injury draws a person's attention to the injured area, making it more likely for the sarcoma to be discovered, in case it had been present for some time
RECENT RESEARCH
Has shown that some of these risk factors affect the DNA of cells in the soft tissues, and certain changes in DNA can cause normal cells to become cancerous.
DNA is the huge molecule that carries the instructions for nearly everything our cells do. We usually resemble our parents because they are the source of our DNA. However, DNA affects more than our outward appearance. The DNA is divided into units called genes. Genes carry the recipes for making proteins, the molecules that determine all cell functions. Some genes contain instructions for proteins that control when our cells grow and divide.
Certain genes that promote cell division are called protooncogenes. Others that slow down cell division or cause cells to die at the right time are called tumor suppressor genes. Cancers can be caused by DNA mutations that turn on protooncogenes or turn off tumor suppressor genes.
Inherited DNA mutations that cause a very high risk of developing breast, colon, kidney, eye, or other cancers have been found in several familial cancer syndromes. In some of these, there is also an increased risk of developing soft tissue sarcomas. Researchers have characterized many of these DNA changes in the past few years.
The only way to prevent some soft tissue sarcomas is to avoid exposure to risk factors whenever this is possible. However, most sarcomas develop in people with no known risk factors, so there is no way known at this time to prevent most cases.