Soft tissue sarcomas grow out of mesenchymal cells, which are stem cells that develop into different types of soft tissue such as fat, muscle, lymph and blood vessels, and nerves. They also can develop into extraskeletal tumours, which are made up of bone and cartilage.
Some sarcomas are of an uncertain tissue type. These include alveolar soft-tissue, clear cell, desmoplastic small round cell tumour, epithelioid, extraskeletal myxoid chondrosarcoma, primitive neuroectodermal tumour (PNET), extraskeletal Ewing tumour, malignant mesenchymoma, malignant perivascular epithelioid cell tumour (PEComa), spindle cell tumour, and synovial tissue. These tumours are rare, but some even rarer types (ex. rhabdomyosarcoma) exist and affect children.
Sarcomas occur at any age, but most commonly in people older than 65 years. There are no genetic links to these tumours; however, there are some risk factors:
- Previous radiotherapy treatment for unrelated cancers, though this is a very small risk.
- Exposure to certain chemicals, such as vinyl chloride used for plastics, weed killers, and dioxins.
- Certain physical conditions, including neurofibromatosis, Gardner’s syndrome, Li-Fraumeni syndrome, and retinoblastoma.
The appearance of symptoms is somewhat uncommon for this type of cancer. They do not manifest themselves for a long period of time and when they do, symptoms will depend on the site affected. For example, if the sarcoma is in a limb (arm or leg), the most common symptom is a swelling of the area that may or may not be painful. If the sarcoma grows in one of the internal organs in the abdomen, it could cause abdominal pain, nausea, vomiting, and constipation with bloody stools. If it is in the uterus, the tumour might cause bleeding and pain in the lower part of the abdomen. If the lung is affected, the tumour may cause coughing and shortness of breath.
Usually, the tumour will be discovered when it is large enough to begin pressing on the affected organ. In the case of bone and cartilage, there are tumours that are also called sarcomas, but they are treated differently from soft tissue sarcomas. Kaposi sarcoma, also called human herpes virus 8, is a rare sarcoma that is associated with HIV infection. It usually affects the skin and shows up as red patches of abnormal tissue.
In order to diagnose a possible sarcoma, the physician will first take a medical history and conduct a physical exam. If sarcoma is suspected, X-rays, ultrasound, CT scans, MRI, and a biopsy can be performed.
Once a cancer diagnosis is confirmed, sarcomas are staged according to how much they have spread. A tumour that is confined to the region where it started has a low stage level. As it spreads to the local lymph nodes and adjacent tissues and organs, the stage level increases.
Treatment for this disease usually involves surgery followed by chemotherapy, radiation therapy, and targeted therapy.