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What Is Sarcoma?

Sarcoma is the general term for a broad group of cancers that can form in various locations in the body, including the bones and the soft tissue (also called connective tissue) that connects, supports, and surrounds other body structures. This includes muscle, fat, blood vessels, nerves, tendons, and the lining of the joints. Most sarcomas occur in the arms, legs, or trunk of the body but can occur anywhere from head to toe. There are more than 150 different types of bone and soft tissue sarcomas.

Sarcomas are rare, accounting for only about 1% of all adult cancers and about 15% of cancers in children. They are usually found when a patient has a lump or bump that does not go away and gets larger over time. Or they may be identified during an X-ray or other imaging scan for another medical issue. 

According to the American Cancer Society, more than 13,400 new cases of soft tissue sarcoma are diagnosed in the U.S. each year, resulting in approximately 5,350 deaths.

Osteosarcoma — the main type of sarcoma that forms in the bones — is less common, with only about 1,000 new cases diagnosed in the United States each year. Around half of these are in children and teens.

Other types of sarcomas, such as Ewing sarcomas account for a smaller percentage of overall sarcoma cancer diagnoses.

Sarcoma Survival Rates and Prognosis

The prognosis for patients with sarcoma depends on the type of sarcoma and the stage at which it is diagnosed. When sarcoma is identified and treated early, the prognosis is generally positive.

The five-year survival rate for patients with small and localized soft tissue sarcomas with the tumor limited to the part of the body where it started is 81%. The majority of all soft tissue sarcomas are discovered at this stage.

Why Come to CU Cancer Center for Sarcoma Cancer

As the only National Cancer Institute Designated Comprehensive Cancer Center in Colorado and one of only four in the entire Rocky Mountain region, the University of Colorado Cancer Center has doctors dedicated to the treatment of sarcoma who provide patient-centered sarcoma cancer care and researchers dedicated to diagnostic and treatment innovations.

→ Two New Grants Help CU Researchers Test New Sarcoma Treatments

The CU Cancer Center is home to the Sarcoma Multidisciplinary Clinic, which offers patients an “all in one” approach to clinical care. At a multidisciplinary clinic, patients are evaluated in one visit by specialists who treat this specific cancer, including world-class medical oncologists, surgical oncologists, orthopedic oncologists, radiation oncologists, interventional radiologists, pathologists, radiologists, nurse practitioners, physician assistants, nurses, social workers, nutritionists, and others, who then collaborate on care. The team also works with plastic surgeons, urologists, thoracic surgeons, cardiologists, and fertility specialists to provide each patient with the optimal course of treatment and follow-up care. 

There are multiple sarcoma clinical trials being offered by CU Cancer Center members at any time. These trials offer patients options beyond traditional sarcoma treatment and can result in remission or increased life spans. Trials conducted by CU Cancer Center doctors have led to the development of some of the most recently approved drugs for sarcoma.

Types of Sarcoma

There are more than 150 different types of sarcoma, and each one is named and classified based on the type of cell in which it forms. These are identified by looking at the cells under a microscope. Doctors use this information to understand the expected growth pattern and aggressiveness of the cancer, which can help determine the best options for treatment.

The most common types of sarcoma are soft tissue sarcomas and bone (osteo) sarcomas. The list below describes some of the most common types of soft tissue and bone sarcomas, but there are many more.

Types of Soft Tissue Sarcoma

Undifferentiated pleomorphic sarcoma (UPS) is most often found in the arms or legs, though it can also form in the soft tissues behind the abdominal organs (the retroperitoneum). The name is based on the way the cancer cells look under the microscope: “undifferentiated” because the cells don't look like the body tissues in which they develop and “pleomorphic” because the cells grow in different shapes and sizes. In the past, UPS was called malignant fibrous histiocytoma (MFH). UPS is most common in older adults.

Liposarcoma begins in fat cells. The tumors can form anywhere in the body but usually occur in the legs or abdomen. Liposarcomas are most common in older adults.

Leiomyosarcoma starts in smooth muscle tissue. The tumors most often form in the abdomen, but they may also be found in other parts of the body, such as the arms, legs, uterus, large blood vessels, and skin.

Rhabdomyosarcoma (RMS) usually forms in skeletal muscle tissue or hollow organs such as the bladder or uterus. RMS is most common in children.

Gastrointestinal stromal tumors (GIST) form in the digestive tract, usually in the stomach and small intestine. GISTs are most common in adults between the ages of 50 and 70.

Fibrosarcoma usually forms in the fibrous tissue in the arms, legs, or trunk. It is most common in adults between the ages of 20 and 60.

Angiosarcoma forms in the lining of the blood vessels and lymph vessels. It occurs most often in the skin on the head and neck, but it may also form in the skin on other parts of the body, such as the breast, or in deeper tissue, such as the liver and the heart. Angiosarcoma may also occur in areas that have received radiation therapy and may develop several years after radiation therapy was delivered.

Desmoid tumors, also called aggressive fibromatosis, most often occur in the connective tissue of the abdomen, arms, and legs. Although desmoid tumors are not technically cancers (because they do not spread to other areas of the body), they can be aggressive and grow into nearby structures and organs. Treatment for desmoid tumors is similar to treatment for sarcomas and is often performed by the same doctors.  

Types of Bone Sarcoma

Osteosarcoma (also called osteogenic sarcoma) is the most common cancer that begins in the bones. It usually forms in areas where the bone is growing quickly, such as near the ends of the leg or arm bones, especially in the bones around the knee and the upper arm bone close to the shoulder. Because it often occurs in areas of bone growth, osteosarcoma is most common in children, teens, and young adults.

→ Disney+ Movie Raising Awareness of Osteosarcoma

Ewing sarcomas (also called Ewing tumors) most often form in the leg bones and pelvis, but they can occur in any bone. Less often, they may form in the soft tissues of the chest, abdomen, arms, legs, or other locations. Ewing sarcoma is most common in children and teenagers.

Chondrosarcoma usually begins in the bones, but it can sometimes occur in the soft tissue near bones. The defining characteristic of a chondrosarcoma is that its cells produce cartilage. Tumors most often form in the pelvis, hip, shoulder, and base of the skull. Chondrosarcoma is most common in middle-aged to older adults.

Sarcoma Causes and Risk Factors

The specific causes for most sarcomas are unclear. In general, cancer occurs when changes or mutations happen in the DNA within cells, causing the cells to grow out of control and form tumors that can damage tissue, bone, organs, and other structures within the body.

Unlike many other types of cancer, sarcomas have very few lifestyle-related risk factors (behaviors that increase a person’s risk of developing a certain type of cancer), such as smoking, sun exposure, diet, etc. However, there are a few risk factors that make someone more likely to develop sarcoma.

Soft Tissue Sarcoma Risk Factors

Age: Although many types of soft tissue sarcoma typically occur in adults, some types, such as rhabdomyosarcoma are more common in children.

Inherited syndromes: Some inherited gene syndromes (also called family cancer syndromes) can increase a person’s risk of developing soft tissue sarcoma. These include hereditary retinoblastoma, Li-Fraumeni syndrome, neurofibromatosis (also called von Recklinghausen disease), tuberous sclerosis, Werner syndrome, Gardner syndrome (a type of familial adenomatous polyposis), and Gorlin syndrome (also called nevoid basal cell carcinoma syndrome).

Radiation exposure: Previous radiation treatment for other cancers (such as breast cancer or lymphoma) can raise the risk of soft tissue sarcomas.

Exposure to certain chemicals: Workers in industries that use large amounts of certain types of chemicals — such as vinyl chloride, herbicides, arsenic, and dioxin — may have a higher risk of soft tissue sarcoma.

Damaged lymph system: When lymph nodes have been removed surgically or damaged by radiation therapy, lymph fluid can build up and cause swelling. This is called lymphedema. Lymphangiosarcoma (a malignant tumor that develops in lymph vessels) is a rare complication of chronic lymphedema.

Bone Sarcoma Risk Factors

Age: The risk of osteosarcoma is highest for people between the ages of 10 and 30 and is at its peak during the teenage growth spurt. The risk decreases in middle age but increases again in older adults. Ewing sarcoma is most likely to occur in children and teenagers. The most prevalent type of chondrosarcoma typically affects middle-aged to older adults.

Height: Children with osteosarcoma are often tall for their age. 

Gender: Osteosarcoma is more common in males than females. However, females tend to develop it slightly earlier, possibly because they often go through their growth spurts earlier.

Race and ethnicity: In the United States, osteosarcoma is slightly more common in Black, Hispanic, and Latinx people than in Caucasians. Ewing sarcoma is more common in people of European ancestry.

Radiation exposure: Previous radiation treatment for other cancers can raise the risk of bone sarcomas in the areas that were exposed to radiation.

Certain bone diseases: People with certain bone diseases have a higher risk of developing osteosarcoma. These include Paget disease, hereditary multiple osteochondromas, and fibrous dysplasia. People with Ollier disease and Maffucci syndrome (conditions marked by an increased number of benign cartilage lesions) have a higher risk of developing chondrosarcoma.

Inherited syndromes: Some inherited gene syndromes (also called family cancer syndromes) can increase a person’s risk of developing osteosarcoma. These include hereditary retinoblastoma, Li-Fraumeni syndrome, Rothmund-Thomson syndrome, Bloom syndrome, Werner syndrome, and Diamond-Blackfan anemia.

Latest in Sarcoma from the CU Cancer Center

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Information reviewed by Breelyn Wilky, MD, in February 2021.