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Soft Tissue Sarcoma

Soft tissue tumors can develop in every type of soft tissue in the body, including nerves, fat, muscle, tendons, the lining of joints, blood vessels, or lymph vessels. They can be malignant (cancerous) or benign. Malignant tumors are known as soft tissue sarcomas (STS). 

These tumors can occur almost anywhere in the body. About 60 percent of soft tissue sarcomas occur in the legs and arms. They can also occur in the trunk, abdomen, and head and neck region. (For tumors that develop in bones and cartilage, see Bone Tumors.)

Small soft-tissue sarcomas may go unnoticed. However, as a STS grows, it can interfere with the body's normal functions.

At UC San Diego Health, people with suspected sarcomas are evaluated by a multidisciplinary team with expertise in sarcoma, as recommended by National Comprehensive Cancer Network (NCCN) and European Society of Medical Oncology (ESMO) guidelines. Studies have shown that patients with these relatively rare cancers have better outcomes at "high volume" cancer centers, defined as those that perform at least 12 sarcoma surgeries per year.  UC San Diego Health is a high-volume center and the regional leader in sarcoma treatment.

Review the tabs at top of this page for information on soft tissue sarcoma types, diagnosis, and treatment.

Types of soft tissue sarcomas

Because there are at least 60 different types of STS, it is more accurately described as a family of related diseases, rather than a single disease. They can include:

  • Liposarcoma: Develops from fat cells, and occurs most commonly in the legs (at the back of the knee and thigh) and in the abdominal area. The most common form of soft tissue sarcoma, it usually occurs in people between 50 and 70.
  • Leiomyosarcoma: This rare tumor develops from smooth muscle tissue, the tissue that makes up involuntary muscle. This type of muscle is found throughout the body, including in the stomach and intestines, the brains, blood vessel walls, skin, and uterus. Leiomyosarcoma occurs most commonly in the abdomen and extremities, but can also affect blood vessels and internal organs and tends to be very aggressive.
  • Rhabdomyosarcoma: This very rare tumor, which affects fewer than 400 people annually in the U.S., generally develops in muscle tissue. It's most common in children and young adults. In young children, it tends to occur in the head and neck, bladder, and vagina, while in older children and young adults it develops in the large muscles of the extremities and the trunk; in adults, it tends to form in the large muscles of the extremities.
  • Synovial sarcomas: This tumor develops near joints and is named for its molecular resemblance to synovial tissue, the tissue lining of the joints. However, it is not believed to arise from this synovial tissue. About 50 percent of synovial sarcomas occur in the legs, followed by the arms.
  • Gastrointestinal stromal tumors (GIST): These develop in the cells that line the walls of the gastrointestinal tract and signal muscles to contract to move food and liquid along the digestive tract. Learn more about GIST.
  • Fibrosarcoma: Develops in the fibrous tissue found at the end of long bones in the arms and legs, and in the trunk. It's most common in adults under 60.
  • Undifferentiated pleomorphic sarcoma (previously known as malignant fibrous histiocytoma or MFH): These develop in fibrous tissue in the arms and legs and occur most often in older adults.
  • Angiosarcomas: Develop in the blood or in lymph vessels. They most commonly occur in skin, soft tissue, liver, breast, spleen, bone, lung and heart.
  • Kaposi’s sarcoma: This cancer of the lining of the lymph or blood vessels occurs most often in patients with AIDS.

At UC San Diego Health, patients undergo a thorough evaluation, including imaging and biopsy, to obtain an accurate diagnosis and determine the optimal treatment.

Symptoms

Often, soft tissue sarcomas present no symptoms in their early stages. When sarcomas develop on the arms or legs, they can cause a lump that grows over a period of time. It may or may not be painful. A sarcoma can cause pain as it grows and exerts pressure on nerves and muscles.

Other symptoms can include worsening abdominal pain and blood in your stool or vomit.

If your physician suspects a soft tissue sarcoma, he or she will order a biopsy so tissue samples can be examined by a pathologist under a microscope. The type of biopsy will be based on the size and location of the tumor. Biopsy types include:

  • Incisional biopsy: The removal of part of a lump or a sample of tissue
  • Core biopsy: The removal of tissue using a wide needle

Staging

The stage of a cancer describes its size and whether it has spread beyond its original area of the body. In sarcoma staging, doctors also evaluate the appearance of the tumor under the microscope and judge how fast the cancer seems to be growing.

  • IA: The cancer cells look either very much like normal cells or somewhat different from normal. The cancer is less than five centimeters (about two inches) in size, and has not spread to lymph nodes or other parts of the body. It may be near the surface or deep.
  • IB: The cancer cells look either very much like or somewhat different from normal cells. The cancer is near the surface and more than five centimeters in size, but it has not spread to lymph nodes or other parts of the body.
  • IIA: The cancer cells look either very much like normal cells or somewhat different from normal. The cancer is deep and more than five centimeters in size, but it has not spread to lymph nodes or other parts of the body.
  • IIB: The cancer cells look very different from normal cells. The cancer is either near the surface or deep and is less than five centimeters in size, but it has not spread to lymph nodes or other parts of the body.
  • IIC: The cancer cells look very different from normal cells, the cancer is near the surface, is more than five centimeters in size, but it has not spread to lymph nodes or other parts of the body.
  • III: The cancer cells look very different from normal cells. The cancer is deep and is more than five centimeters in size, but it has not spread to lymph nodes or other parts of the body.
  • IV: The cancer may have spread to lymph nodes in the area or may have spread to other parts of the body, such as the lungs, head, or neck.
  • Recurrent: The cancer has returned (recurred) after being treated. It may recur in the tissues where it originally started, or elsewhere.

Treatment options for soft tissue sarcomas include surgery, radiation therapy, and chemotherapy. The combination of treatments will depend on the type and stage of the sarcoma.

Surgery

The primary treatment for most soft tissue sarcomas is surgery to remove the tumor. UC San Diego Health surgeons are experienced in treating these rare cancers, and use the latest advances in surgical techniques, including minimally invasive procedures. 

In many cases, we can use new organ-sparing procedures to completely remove tumors while preserving nearby organs and function. In cases where organs or vessels do needs to be removed, we can perform reconstructive or vascular surgery to maintain function.

Radiation therapy

Although surgery is the primary treatment for most sarcomas, radiation therapy is often considered as an additional treatment to reduce the risk of recurrence. It can be used before surgery to shrink soft tissue tumors (especially in the arms and legs) and make them easier to remove, or after surgery to kill any cancer cells that may have been left behind. 

UC San Diego Health radiation oncologists use an advanced technology known as intensity modulated radiation therapy, or IMRT, to precisely target the tumor and reduce damage to surrounding healthy tissues. For more information, see Radiation Therapy for Sarcoma.

Chemotherapy

Chemotherapy, the use of anti-cancer medications, may be used to shrink tumors and make the tumor easier to remove through surgery or radiation treatment. Chemotherapy before surgery is called neoadjuvant treatment.

Chemotherapy that follows radiation or surgery is known as adjuvant treatment, and is used to destroy any remaining malignant cells in order to decrease the risk of recurrence.

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