Medically reviewed in March 2022
Also abbreviated as STS, soft tissue sarcoma is cancer that begins in the soft tissues of the body, such as adipose tissue, muscles, nerves, connective tissue and tissues of the gastrointestinal tract. Below are a few basic facts about STS that will help give you an overview of the disease, including how it is diagnosed and how it is treated.
There are many different subtypes
There are more than 50 different subtypes of soft tissue sarcoma, and nearly any soft tissue in the body can be affected. Some subtypes are more common that others. The most common subtype in adults is liposarcoma, STS that begins in adipose tissue, which accounts for roughly one in five cases. Rhabdomyosarcoma, which affects the muscles attached to bones, is the most common form in children.
Many patients have no symptoms
In many cases, patients with soft tissue sarcoma do not have any symptoms beyond a noticeable lump that can be felt beneath the skin. These lumps can go unnoticed until the tumor grows in size and causes pain and/or inflammation, or impairs the normal functioning of the part of the body where it is located. Soft tissue sarcomas located in the gastrointestinal tract (called gastrointestinal stromal tumor or GIST) may cause symptoms such as abdominal pain, nausea, vomiting, blood in the stool or vomit, bowel obstruction and anemia (tiredness due to low blood cell count as a result of bleeding in the GI tract).
Diagnosis can be a challenge
Diagnosis of soft tissue sarcoma typically involves a combination of imaging tests (such as X-rays, MRIs, ultrasounds and others) and biopsy, where a sample of a tumor is taken, either with a needle or during surgery. Imaging tests can tell healthcare providers a lot about the size, location and appearance of the tumors. Biopsy and laboratory testing of the tissue samples is done to identify the subtype of soft tissue sarcoma. However, in some cases, a patient will be diagnosed with what is called an uncertain type of STS, which means the oncologists know that the cancer is STS, but cannot determine the subtype.
Causes and risk factors are (mostly) unknown
Research has uncovered several risk factors for soft tissue sarcoma, which include genetic conditions, having received radiation therapy for treatment of another cancer and exposure to certain chemicals. Some subtypes are more common in older adults, but others affect people of all ages, including younger adults and children. But for most patients with STS, there is no identifiable cause.
Only one subtype of STS has an identifiable cause—Kaposi sarcoma, which is caused by infection with a virus known as human herpesvirus 8 (HHV8) or Kaposi sarcoma associated herpesvirus (KSHV). Kaposi sarcoma causes cancerous lesions underneath the surface of the skin and throughout the body.
Treatment usually involves surgery
Surgery is the most often used method of treatment for most types of soft tissue sarcoma. In cases where tumors are small and localized (meaning they are confined to a single location in the body), surgery may be the only treatment that is needed. In other cases, surgery will be used in combination with radiation therapy and/or chemotherapy. Some subtypes of soft tissue sarcoma can also be treated with targeted therapy drugs, which are drugs that are designed to target specific molecules found in certain types of cancer cells. Chemotherapy and targeted therapy drugs may also be used after an initial treatment is complete, to help prevent the cancer from returning. The choice of treatment will depend on numerous factors about both the cancer and the patient.
