Soft tissue sarcomas arise in tissues such as fat, muscles, nerves, tendons, and blood and lymph vessels — the soft tissues that connect, support, and surround other parts of the body.
Sarcoma is rare, representing only about 1 percent of all cancer cases. According to the American Cancer Society, approximately 5,700 men and 4,700 women were diagnosed with soft tissue sarcoma in the United States in 2008. However, patient data from the National Cancer Institute suggests that the numbers may be higher, depending on which specific cancers are included in the diagnosis category. (The numbers put forth by the American Cancer Society include sarcomas diagnosed in both adults and children.) Exact numbers are difficult to obtain because these tumors often are incorrectly classified as primary cancers of other organs to which sarcoma has spread from its original location in the body.
Soft tissue sarcomas present unique challenges in detection and treatment. Sarcomas are unusual in that they can occur in any site of the human body, although about 50 percent occur in the limbs. There are more than 50 different types of soft tissue sarcomas and sarcoma-like growths. Major types of soft tissue sarcomas in adults include:
|Type of Sarcoma
||Tissue of Origin
||Fat tissue, usually in the arms, legs, or body cavities
||Begins in fibrous tissue, which holds bones, muscles, and other organs in place
|Malignant Fibrous Histiocytoma
||Tendons and ligaments (fibrous tissue), usually in the arms, legs, or trunk
||Involuntary muscle (smooth muscle), such as that found in the uterus and digestive tract
||Peripheral-nerve sheaths in arms, legs, or trunk
||Skeletal muscle, usually in arms or legs
||Cell of origin unknown
In a survey of the approximately 8,000 soft tissue sarcoma patients admitted to Memorial Sloan-Kettering from 1982 to 2009, the following information about the original site of the sarcoma was reported:
- 32 percent of sarcomas were found in a lower extremity
- 18 percent in the viscera (organs located within the chest and abdomen, such as the stomach, kidney, uterus, etc.)
- 15 percent in the retroperitoneal region (the area outside or behind the peritoneum, which is the tissue that lines the abdominal wall)
- 13 percent in an upper extremity
- 8 percent in the trunk
- 14 percent in other sites
Since there are many subtypes of soft tissue sarcoma, each with differing characteristics, the risk and seriousness of the disease can vary widely. In some patients, sarcomas are minor, non-threatening tumors that can be cured with simple surgery. In others, the tumors can be large and much more aggressive, requiring chemotherapy and radiation therapy as well as surgery.
In addition, the capacity of sarcomas to metastasize (spread) to other sites also varies widely. If metastasis occurs, the cancer can sometimes be cured with surgery; in other instances, it can be a life-threatening problem. If the sarcoma tumor is small (less than 5 centimeters), diagnosed as low-grade, and is detected early (before it has had a chance to spread), the five-year survival rate is approximately 90 percent.
Most soft tissue sarcomas do not have any identifiable risk factor. Some types of sarcoma are more common in specific age groups — for example, rhabdomyosarcoma is more common in children than in adults, and synovial sarcomas are more common in adolescents. But sarcomas occur at all ages, in both men and women.
Doctors recognize some familial syndromes that can predispose people to sarcoma, including neurofibromatosis, Gardner’s syndrome, Li-Fraumeni syndrome, and retinoblastoma.
Other factors that have been associated with soft tissue sarcomas include prior exposure to radiation, chronic lymphedema (a condition in which excess fluid collects in tissue and causes swelling, often in the arms and legs), and in rare instances, exposure to certain chemicals. Cancer of the lymph nodes (lymphangiosarcoma) can develop when lymph nodes have been surgically removed or damaged by radiation therapy (both rare in current practice).
The ability to identify patients at risk for soft tissue sarcoma may eventually lead to new ways to detect the disease early, determine at which stages it is most curable, and improve treatments. Memorial Sloan-Kettering researchers are investigating whether particular risk factors — including family history of the disease, lifestyle, occupation, genetic makeup, or environmental exposure to certain chemicals — may contribute to the development of the disease.
Because they occur in soft (usually elastic) tissue that is easily pushed out of the way by the growing tumor, soft tissue sarcomas often do not cause early symptoms, and there is not yet a routine screening test available to detect such tumors before symptoms appear.
- The first noticeable symptom usually is a painless lump. Eventually the tumor might cause some pain or soreness as it impinges on nerves and muscles. In many cases, an injury not related to the cancer draws attention to the presence of the sarcoma.
- Sometimes abdominal sarcomas can cause blockage in the gastrointestinal system, or blood in vomit or stool.
- These symptoms can be caused by conditions other than cancer and should be evaluated by a physician.