Soft tissue sarcomas are cancerous tumors that grow in muscles, fat, joints, nerves or blood vessels. Soft tissue sarcomas make up 1percent of all cancer types and have been estimated to occur approximately 30 cases among every one million people. Studies have connected soft tissue sarcomas to exposure certain chemicals, high-dose radiation, and certain viral infections, and to specific genetic abnormalities. In most cases, the cause is unknown.
|Examples of Soft tissue sarcomas|
|Joint||Malignant tenosynovial Giant Cell Tumor|
|Smooth muscle (seen in blood vessels and intestines)||Leiomyosarcoma|
|Skeletal muscle (seen in trunk and limbs)||Rhabdomyosarcoma|
The World Health Organization identifies 19 categories and more than 50 histologic (microscopic make-up of tissues) types of soft tissue sarcomas. Each type behaves differently, with variable chances of spreading to other organs. If you have a soft tissue sarcoma, you will usually notice an enlarging mass in the trunk or limbs. This may or may not cause pain, numbness and/or skin breakdown when the mass eventually presses on the surrounding tissue structures.
See your doctor to diagnose soft tissue sarcoma. Benign (not cancerous) soft tissue tumors are much more common than malignant ones (cancerous / sarcomas). It is important for your doctor to evaluate you thoroughly to identify the mass. In general, masses that are large (i.e. bigger than 5 cm) and located deep in the tissues are more likely to be cancerous. In this case, you should be seen by a cancer specialist (oncologist).
Your doctor will perform several tests to determine the prognosis (prediction of outcome for a disease) of a soft tissue sarcoma. The doctor uses imaging studies and tests to determine how much a tumor has grown and whether any other areas of the body are involved. MRI (Magnetic Resonance Imaging ) is used to identify a tumor's size and depth, as it clearly shows a tumor's relationship to normal muscle, fat, nerves and blood vessels. MRI's are also used for guiding biopsies (process of taking tissue samples of the tumor), checking the tumor's response to treatments, and observing the disease progression.
Plain radiographs (X-rays) are only used for large, deep, soft tissue masses that are fixed to bone. Xrays often help in diagnosing some tumors like synovial sarcoma and liposarcoma that have calcium deposits. A computerized tomography scan (CT scan or CAT scan), can also be used to clearly outline how much bone is involved. The CT scan is a useful tool in detecting spread of the cancer to the lungs, abdomen and pelvis. It is sometimes used instead of an MRI for masses that are located around a metal implant. Bone scans are used to detect the spread of a tumor into a bone. Positron Emission Tomography (PET scan) is a new imaging test used to detect and monitor a tumor's response to treatment.
In addition to identifying the size and depth of the tumor, another important factor in staging is determining the grade (aggressiveness of the cancer cells) of the soft tissue tumor. The biopsy (tissue specimen) enables a pathologist to identify the type of the cancer, where it came from, and whether it is of high or low grade. The doctor is very careful when taking biopsy samples to avoid the risk of contaminating normal tissue with cancer cells.
Multidisciplinary treatment for soft tissue sarcomas
A multidisciplinary treatment team includes the surgeon, radiation oncologist, medical oncologist and pathologist. The doctor's main goal is to control the local and distant spread of the tumor with the least amount of disability in terms of your function and quality of life. The key is adequate resection (removal of tumor) through a properly planned surgery.
The choice to do an amputation (cut at the level of a bone) or a limb-sparing procedure (surgery that preserves the limb) depends on the amount of tissue that needs to be removed and the functional outcome that is expected afterwards. Limb preservation is often desired, but if an adequate removal of the tumor would require sacrificing important nerve and muscle structures, making the involved limb numb and useless, it may be more beneficial to have an amputation or disarticulation (cut at the level of a joint) with proper artificial limb attachment.
Radiation therapy is often combined with surgery to lower the risk of local recurrence (regrowth of the tumor). Radiation can be administered either before or after the tumor is removed. The timing of the radiation depends upon the tumor site and the doctor's judgment.
The role of chemotherapy in treating soft tissue sarcomas is still controversial. At best, there is modest benefit in improving survival through chemotherapy. The chemotherapy drugs that have been most effective against soft tissue sarcomas are doxorubicin (adriamycin®) and ifosfamide (Ifex®). Newer drugs that target specific cellular traits are being researched. The first drug to work by this method was imatinib (Gleevac®), which has been effective at treating a specific type of sarcoma—gastrointestinal stromal tumor. Chemotherapy is mainly used in tumors with a poor outcome—for instance, in large, high-grade tumors that have a high risk of spread to other body sites.
After treatment of soft tissue sarcomas, it is important to follow-up consistently with your doctor. Tumors that come back may pose a serious problem; it is better to detect them early. A recurrent tumor could regrow at the original site or in a distant site such as the lungs (metastasis). In some patients, cutting away localized or metastatic disease can provide a better outcome and extend their lifespan.
This tumor is composed of fatty tissue, which usually appears as an enlarging, painless mass deep in the muscles of the limbs. It can also occur in the abdomen or buttock, where it can stay undetected for a long period of time and possibly evolve to a more aggressive type. A complete surgical removal of the tumor is needed. It is commonly seen in adult men and women over age 50. The course of the disease depends on the type and location of the tumor. There are several types of liposarcoma. The well differentiated liposarcoma occurs in the limbs and rarely spreads to other organs; it almost never results in death. The more aggressive / dedifferentiated type is commonly located in the abdomen or groin and has a higher chance of recurring locally and spreading to distant areas. Another fairly common type is myxoid liposarcoma which, although very rare, occurs in patients younger than 20 years old and is often seen in the deep thigh muscles. The round cell liposarcoma sometimes is seen together with the myxoid type and is prone to recur and spread to other organs, giving it a poorer prognosis.
This is a malignant tumor made up mostly of cells of fibrous tissues and collagen. Two different clinical behaviors characterize the two main groups of fibrosarcoma. Adult fibrosarcoma occurs in middle-age to older adults and is commonly seen in the deep, soft tissues of the extremities and the trunk. Studies have linked this tumor with irradiation and, in rare cases, of implanted foreign material in the body. It can spread to the lungs and bone; the mortality rate can be rather high depending on the aggressiveness (grade) of the tumor cells. Infantile fibrosarcoma differs from the adult form in many ways. Most cases are congenital (present at birth); it almost never occurs past the age of two years. It has a better outcome with a lower chance of local recurrence and spread. This type can grow fast and wounds can develop on the skin. It can be surgically removed.
Malignant Fibrous Histiocytoma:
This is the most common malignant soft tissue tumor in late adulthood. It is divided into four subtypes based on the predominating cells present. The most common location is in the lower limbs, particularly the thigh region, where it can appear as a painless mass. Less frequently, it can grow in the abdomen and be undetected until the patient starts to develop symptoms related to an increase in abdominal pressure, such as bloating, frequent urination or constipation. There have been some reports of malignant fibrous histiocytoma developing in patients who received high-doses of radiation for many years in the past, and other reports suggest a viral or a chemical cause. In most cases, the origin is not known.
This is the most common malignant soft tissue tumor in children. It happens most often between the ages of 2 and 6, and between ages of 14 and 18. The botryoid and embryonal subtypes can occur earlier in infancy through age 15. The alveolar subtype occurs on average at age 16. The tumor can grow quite large in a short period of time, causing pain, discomfort or joint stiffness due to pressure on the adjacent soft tissue structures. It is seen mostly in the head and neck region. In 25 percent of cases, it is found on the trunk and limbs. This tumor is aggressive and difficult to control.
These tumors occur deep in the muscle of both the upper (25 percent) and lower limbs (70 percent) and are common in early adulthood, particularly among young males in their 30's. The mass remains small for some time but can noticeably enlarge. Sometimes there is a history of trauma preceding the mass. Recent studies show that a genetic abnormality is present in the tumor cells. The risk of spread, mostly to the lungs, can be high and can take as long as 5 to 10 years. This is why a long term follow-up period is recommended after treatment.
This rare tumor most often develops in the forearm and hand but may also be seen on the trunk or legs. Patients typically are males in their teens or 20's. The tumor can be deceiving because it can mimic benign (not cancerous) masses in the hand, including small tumors just beneath the skin that may resemble an infection. The source of this tumor is not clear, but a genetic abnormality involving an immature cell type is likely. There is no known hereditary pattern (trait transferred from parent to offspring). Risk of recurrence is very high, and is usually due to an incomplete removal of the initial lesion. It can spread to the lungs and lymph nodes and affect the likelihood of survival.
Alveolar Soft Part Sarcoma:
This rare, slowly growing tumor occurs mainly in adolescents, and develops in the deep thigh area in nearly half of cases, although they tend to develop in the head and neck region in younger children. The tumor normally contains numerous blood vessels, so tests such as angiography and CT scan are done to identify possible sources of bleeding during surgery. Other organs, such as the lungs, bones and brain, may be affected and cause a patient to seek treatment. Survival depends on the size of the tumor and the presence of distant spread. However, in contrast to other types of cancers, the metastatic tumors in the lungs may grow very slowly over many years.
Clear Cell Sarcoma:
Clear cell sarcoma is a tumor common in young adults between the ages of 20 and 40, and is believed to be caused by a genetic abnormality. There is no known hereditary pattern. It grows just beneath the skin, affecting tendons and muscle sheaths of the limbs, particularly in the foot and ankle region. The mass can cause pain, and patients sometimes develop lymph node enlargements in the armpits or groin, signifying cancer spread. Recurrences and distant spread to the lungs and bone are common, and can occur even after 10 years. Long-term follow-up is recommended.
Middle-aged and older adults are commonly affected by this tumor, which may arise from blood vessels of the trunk and limbs. It can obstruct blood flow to vital organs such as the liver, kidneys, and pancreas. Jaundice, nausea, abdominal distention and leg swelling are some possible manifestations. Tumors that are located in the limbs are easier to control than the more common abdominal tumors, which tend to be larger and more difficult to remove. It may spread to the lungs and the liver.
Gastrointestinal Stromal Tumor (GIST):
A rare tumor arising in the abdomen, GIST tends to occur in adults. Tumors may become quite large before being noticed. For this reason, complete surgical removal is difficult to achieve, compared with sarcomas in the extremities. The development of drug therapy targeted at specific characteristics of cancer cells in GIST has improved the treatment of this tumor compared with surgical removal alone. The first drug that worked with this method was imatinib (Gleevac®). Other drugs are in development and testing phases.
Information regarding overall prognosis and survival rates for soft tissue sarcomas can be taken from combined experiences treating a large number of patients. Remember, every type of tumor has its own course, and every patient will respond to disease and treatment differently. Most major cancer centers report overall survival rate for patients with soft tissue sarcoma in the range of 60 percent at 5 years. Survival rates depend on the patient's age and gender, as well as the size, grade and stage of the tumor when it was first identified. The best results are achieved with small, superficial tumors (i.e., smaller than 5 cm); that are less aggressive (low grade); and have not spread to lymph nodes and other organs.
Complete surgical removal can control the tumor in about 80 percent of cases; adding radiation therapy can improve rates to as much as 90 percent to 95 percent. Incomplete surgical removal and the presence of distant spread to other organs will give a poorer outcome. After the tumor has been removed, one can expect a 5 percent to 20 percent chance of the tumor regrowing at the same site and a 30 percent to 50 percent chance of it growing in a different organ. Surgical removal of the metastatic lesion (metastatectomy) is possible and is recommended for appropriate patients.
Expanding knowledge about tumor cells and their methods of progression and spread should provide new therapeutic targets for study. The future of treatment for soft tissue sarcomas relies heavily on the accumulation of more data defining the role of chemotherapy in soft tissue sarcoma management, combination therapy for cases with poor prognosis and presence of distant spread, and development of new drugs targeted at specific tumor cell characteristics. Ultimately, improvement in the odds of surviving a soft tissue sarcoma will result from better disease detection and diagnosis, improved surgical techniques, better radiation methods, and more effective chemotherapy agents.
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