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Soft tissue sarcoma is a cancer of the soft tissue of the body. There are many subtypes of soft tissue sarcoma, such as synovial sarcoma and alveolar soft part sarcoma. About 80% of all sarcomas are soft tissue sarcomas.
Fred Hutch Cancer Center has physicians who specialize in soft tissue sarcoma and have a deep knowledge of these types.
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Soft Tissue Sarcoma Overview
Even though soft tissue sarcoma is the most common type of sarcoma, it is a rare disease. The estimated new cases of soft tissue sarcoma in the United States was 13,520 in 2025, according to the National Cancer Institute.
Soft tissue sarcoma can form in many different parts of the body where there is soft tissue. The most common areas include:
- Arms
- Legs
- Abdomen
- Retroperitoneum (area outside or behind the peritoneum, the tissue that lines the abdominal wall)
Types of Soft Tissue Sarcoma
The most common types of soft tissue sarcoma in adults are:
- Alveolar soft part sarcoma: This type usually starts in the leg but it can originate in other parts of the body such as the arms, head or neck. This is one of the rarest sarcomas.
- Epithelioid sarcoma: This is a type of cancer that grows in soft tissues of the body like muscles, fat or blood vessels. There are two main types of epithelioid sarcoma, which are distal epithelioid sarcoma and proximal type epithelioid sarcoma.
- Gastrointestinal stromal tumors: The most common sarcoma of the gastrointestinal tract.
- Kaposi sarcoma: This type starts in the cells that line your blood vessels and lymph vessels.
- Leiomyosarcoma: Develops from the smooth muscle in abdominal and pelvic organs and blood vessels.
- Liposarcoma: Develops from fat tissue. Most often, it is found in the back of the abdominal cavity. However, it can also be found in the soft tissues of the arms and legs.
- Retroperitoneal sarcoma: This type grows in the muscles, nerves and other soft tissues at the back of the abdomen.
- Synovial sarcoma: Usually appears in muscles or ligaments in the arms, legs or feet near a joint.
Sarcomas That Can Be Soft Tissue Sarcoma or Bone Sarcoma
There are some sarcomas that can be both soft tissue or bone. They include:
- EHE sarcoma: Epithelioid hemangioendothelioma (EHE) sarcoma starts in the cells that line blood vessels.
- Ewing sarcoma: This type usually grows in the bones but can sometimes start in soft tissues. It usually grows in the long bones of the arms or legs, but it can also show up in the pelvis, chest wall or spine.
- Spindle cell sarcoma: The type typically develops in soft tissue but it can also develop in the bones. It usually grows in the long bones of the arms and legs, or in the pelvis.
- Undifferentiated pleomorphic sarcoma: This type usually develops in the soft tissues of the arms or legs. While rare to develop in the bones, it can.
Treatment for Soft Tissue Sarcoma
Treatment for soft tissue sarcoma is determined by the subtype and stage as well as other factors. These can include surgery, chemotherapy, radiation or immunotherapy.
Childhood (Pediatric) Soft Tissue Sarcoma
Soft tissue sarcoma, as well as bone sarcomas, are rare in children. There are many treatment options for children and teenagers with soft tissue sarcoma. Fred Hutch Cancer Center – Proton Therapy offers proton therapy for certain childhood cancers, including soft tissue sarcoma. Learn more about proton therapy for childhood cancers.