Sarcoma, Soft Tissue
"Sarcoma" comes from a Greek word meaning "fleshy growth." Soft tissue sarcomas are cancerous (malignant) tumors that originate in the soft tissues of your body. Soft tissues connect, support and surround other body structures. The soft tissues include muscle, fat, blood vessels, nerves, tendons and the lining of your joints (synovial tissues). A large variety of soft tissue sarcomas can occur in these areas.
Soft tissue sarcomas aren't common. They occur slightly more often in men than in women, and they sometimes occur in children and adolescents.
Although there are various types of soft tissue sarcoma, they generally share similar characteristics, produce similar symptoms and are treated similarly — with surgery, radiation therapy or chemotherapy, or with a combination.
Soft tissue sarcomas go by a variety of names, depending on the tissue in which they originate. Locations of sarcomas and their names include :
- Muscle. You have two types of muscles: skeletal and smooth. Skeletal muscles move bones and are under your voluntary control. You can't control smooth muscles, which line blood vessels and organs, such as the uterus and gastrointestinal tract.
Sarcomas that arise from muscles include rhabdomyosarcomas, which occur in skeletal muscles, most commonly in your arms and legs. There are multiple subtypes of rhabdomyosarcoma, including embryonal sarcomas, which tend to occur in the head, neck and genitourinary tract of children ages 4 and younger; and alveolar rhabdomyosarcomas, which occur in the arms, legs, head and neck of children. Leiomyosarcomas, which are more common in adults, occur in the smooth muscles, most commonly in the uterus, gastrointestinal tract or lining of blood vessels.
- Blood vessels. These include hemangiosarcomas, which most commonly occur in blood vessels of your arms, legs, head and trunk; infantile hemangiopericytomas, which generally occur in blood vessels of the arms, legs, trunk, head and neck of children ages 4 and younger; and Kaposi's sarcomas, which occur in blood vessel walls, most commonly in people with immune deficiencies such as HIV/AIDS.
- Lymph vessels. Called lymphangiosarcomas, this type occurs in lymph vessels, most commonly in your arms. These sarcomas are sometimes seen in tissue that's been exposed to radiation, such as the arm on the same side as a breast treated for breast cancer.
- Synovial tissue. A type called synovial sarcomas occurs in the tissue around joints such as your knees and ankles. Synovial sarcomas typically occur in children and young adults.
- Nerves. Neurofibrosarcomas occur in the peripheral nerves of your arms, legs and trunk.
- Fat. Liposarcomas occur in the fatty tissues, often in your arms, legs and trunk.
- Fibrous tissue. These include fibrosarcomas, which usually occur in your arms, legs or trunk; malignant fibrous histiocytomas, which tend to occur in your arms or legs; and dermatofibrosarcomas, which grow in the tissue beneath your skin and typically occur in your trunk or limbs.
- Mesothelial tissue. This type of tissue provides a protective lining for certain organs, such as your lungs, heart and intestines. Malignant tumors that arise from mesothelial tissue are called mesotheliomas; they most commonly occur in your lungs.
In general, no one knows for certain what causes most soft tissue sarcomas. Known causes include asbestos for most cases of mesothelioma, and viruses for Kaposi's sarcoma in people with defective immune systems.
In a few cases, sarcomas may be hereditary, such as in :
- Inherited retinoblastoma. This rare form of childhood eye cancer may increase a child's risk of soft tissue sarcoma.
- Li-Fraumeni syndrome. This condition is characterized by an increased risk of many cancers, including sarcomas, leukemia, breast cancer, ovarian cancer and others.
- Gardner's syndrome. This hereditary disease leads to precancerous and cancerous growths in the intestines and abdomen.
- Neurofibromatosis. This condition results in developmental changes in the nervous system, causing nerve sheath tumors. Other abnormalities associated with neurofibromatosis include skin changes and bone deformities.
Radiation is occasionally associated with sarcomas. These have usually occurred as a side effect of radiation therapy given for other cancers, such as breast cancer or lymphoma. But radiation therapy is becoming more and more sophisticated, which may lead to fewer of such side effects. For example, doctors today are better able to regulate doses of radiation and precisely target the tumor being treated.
Other factors that may lead to increased risk of soft tissue sarcomas, but have not been proved, are exposure to high doses of chemicals such as :
When to seek medical advice :
- Vinyl chloride, used in making plastics
- Dioxin, an unwanted byproduct of incineration
- Herbicides that contain the chemical phenoxyacetic acid
Talk to your doctor if you develop a lump that persists or if you have signs or symptoms that may indicate a soft tissue sarcoma, such as worsening abdominal pain or blood in your stool. Some soft tissue tumors are noncancerous (benign). However, the only way to determine whether a tumor is cancerous or not is for a doctor to examine a sample of the tissue.
Soft tissue sarcomas can occur anywhere in your body, but the largest number — about half — occur in the arms, legs, hands or feet. Another 40 percent occur in the trunk, which includes the chest, back, hips, shoulders and abdomen. About 10 percent are found in the head and neck. Soft tissue sarcomas usually produce no signs and symptoms in their early stages. As the tumor grows, it may produce a lump or swelling. Later it may cause pain if it presses on nerves or muscles. If the tumor is located in the abdomen, it may cause blockage or bleeding of the stomach or intestines.
If your doctor suspects you have sarcoma, he or she will take a medical history and perform a physical exam. Although your doctor may be able to feel the presence of a mass or a lump (tumor), determining whether the tumor is malignant requires removal of a sample of tissue (biopsy) from the tumor for examination. If your doctor suspects you have soft tissue sarcoma, ask for a referral to a cancer doctor (oncologist) who specializes in sarcomas before the biopsy is performed. Soft tissue sarcoma is fairly rare and is best addressed by someone who has experience with it.
Techniques for removing a sample of a suspected soft tissue sarcoma include :
- Needle biopsy. Your doctor uses a thin needle to remove small pieces of tissue from the tumor. There are two types of needle biopsy — fine-needle aspiration and core biopsy. A core biopsy involves using a slightly larger needle to remove a small, solid core of tissue.
- Surgical biopsy. Your doctor makes an incision through your skin and removes either the entire tumor (excisional biopsy) or a portion of the tumor (incisional biopsy). In some cases you may need only local anesthesia. For a larger or deep-seated tumor, you'll likely require general anesthesia for the procedure. It's important that a doctor experienced in the treatment of sarcomas perform the excisional biopsy.
Imaging tests, such as X-rays, computerized tomography (CT) scans, ultrasound, magnetic resonance imaging (MRI) and positron emission tomography (PET), also may be done to enable your doctor to see and evaluate the area of concern.
Grading and staging
Besides determining whether the tissue is cancerous, examining tissue can determine how aggressive the cancer is (its grade). Further testing, such as with imaging scans and blood tests, can help determine if the cancer has spread and how far (its stage).
Soft tissue sarcomas, like many cancers, are staged according to a system developed by the American Joint Committee on Cancer. With soft tissue cancers, the oncologist looks at tumor size and location, its spread to lymph nodes, its spread to distant organs and its grade — how much the tumor looks like normal tissue, which indicates how quickly it's growing — to determine whether the cancer is stage IA, representing tumors that are small and haven't spread, through IVB, which represents cancer that has spread to other parts of the body.
Survival is based on a number of factors, including the type of cancer, at what stage the cancer was discovered and where the tumor is located. Generally, sarcomas of the arms and legs have a better outcome than do other sarcomas. If the tumor is very small and localized, the five-year survival rate is around 90 percent. If the cancer has begun to spread, however, survival becomes more difficult.
With soft tissue sarcomas, tumors can grow large, press on normal tissue and cause soreness or pain. If the cancer spreads to other organs, complications include dysfunction of the affected organ, such as shortness of breath if it spreads to your lungs.
As with other cancers, treatment for sarcomas depends on the size, type, location and stage of the sarcoma, including whether it has spread to the lymph nodes or other parts of your body, and your overall health.
Surgery is the most common treatment for soft tissue sarcomas, especially if cancer cells haven't spread to other parts of the body. Surgery generally involves removing the cancer and a rim of healthy tissue surrounding it. If the only area the cancer has spread to is the lungs, surgical removal of the primary and secondary tumors may be possible.
In the past, amputation was common for soft tissue sarcomas in an arm or leg. Today, advances in surgical techniques and chemotherapy before surgery (neoadjuvant chemotherapy) or after surgery (adjuvant chemotherapy) and radiation therapy make limb-sparing surgery possible in most cases. However, amputation may be necessary to remove all the cancer from soft tissue sarcoma in an arm or leg that has invaded nerves, arteries or muscles.
Radiation therapy — also called radiotherapy or X-ray therapy — involves treating cancer with beams of high-energy particles, or waves (radiation), such as gamma rays or X-rays. Although radiation can affect healthy cells as well as cancer cells, it's much more harmful to cancer cells because cancer cells divide more rapidly than most healthy cells do. Cells are more vulnerable to damage when they're dividing, making cancer cells more susceptible to radiation than normal cells are. In addition, normal cells can recover from the effects of radiation more easily than cancer cells can.
Many people with cancer undergo some type of radiation therapy. Your doctor may suggest using radiation therapy at different times during your cancer treatment and for different reasons, such as before surgery to shrink a cancerous tumor or after surgery to stop the growth of any remaining cancer cells. In addition, doctors sometimes use radiation therapy to shrink tumors to decrease the pressure, pain or other symptoms they may cause.
Chemotherapy uses medications to kill rapidly dividing cells. These cells include cancer cells, which continuously divide to form more cells, and healthy cells that divide quickly, such as those in your bone marrow, gastrointestinal tract, reproductive system and hair follicles. Healthy cells usually recover shortly after chemotherapy is complete — so, for example, your hair soon starts growing again.
Unlike radiation therapy, which treats only the part of your body exposed to the radiation, chemotherapy treats your body as a whole (systemically). As a result, it treats cells that may have escaped from where the cancer originated.
Depending on the type of cancer you have and whether it has spread, your doctor may use chemotherapy to :
- Eliminate all cancer cells in your body, even when cancer is widespread
- Prolong your life by controlling cancer growth and spread
- Relieve symptoms and enhance your quality of life
In some cases, chemotherapy may be the only treatment you need. More often, doctors use chemotherapy in conjunction with other treatments, such as surgery or radiation, to improve results.
In addition to chemotherapy, some drugs inhibit certain enzymes that are critical to the development and growth of a tumor. One of these new drugs, imatinib (Gleevec), is used to treat a type of sarcoma called gastrointestinal stromal tumor. Other types of cancer-fighting drugs are being explored in ongoing clinical trials.