 Alveolar Soft Part Sarcoma
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Alveolar soft part sarcoma is a malignant soft tissue tumor (cancer that originates in soft connective tissues of the body) that has an unclear origin. Most soft tissue sarcomas have similarities to certain types of normal tissue. For example, synovial sarcoma resembles normal synovial (joint) tissue. Leiomyosarcoma resembles normal muscle tissue. However, microscopic evaluation and other laboratory tests do not definitively show the origin of some soft tissue sarcomas, including alveolar soft part sarcoma.
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This kind of tumor, rare among children, is a slow-growing tumor that usually arises in the thigh or legs, although it sometimes is initially found in the head and neck. Alveolar soft part sarcoma can spread (metastasize) to other areas of the body. It tends to recur or metastasize to the lung and brain years after diagnosis.
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As a group, soft tissue sarcomas other than? rhabdomysarcoma which is slightly more common, account for less than 1 percent of all new cancer cases each year and 3 percent of all childhood tumors.
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The exact cause of soft tissue sarcomas is not entirely understood, however, studies have indicated that genetic alterations may play a role. Researchers have studied a small number of families that contain several members of one generation who have developed soft tissue sarcomas. In addition, limited studies have shown a possible link between soft tissue sarcomas and the development of other types of cancer.
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Certain inherited diseases are also associated with an increased risk of developing soft tissue sarcomas. These include people with Li-Fraumeni syndrome (which involves alterations in the p53 gene) or neurofibromatosis (which involves alterations in the NF1 gene). For some soft tissue tumors, there seems to an association with an Epstein-Barr virus infection.
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Because alveolar soft part sarcoma affects tissue that is elastic and easily moved, a tumor may exist for a long time before being discovered, growing large and pushing aside surrounding tissue. The following are the most common symptoms of soft tissue sarcomas. However, each child may experience symptoms differently:
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- A painless swelling or lump
- Pain or soreness caused by compressed nerves or muscles
- Limping or other difficulty using the legs and feet
- Diminished range of motion in the affected area
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The symptoms of alveolar soft part sarcoma may resemble other conditions or medical problems. Always consult your child's physician for a diagnosis.
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In addition to a complete medical history and physical examination, the most conclusive diagnostic procedure for alveolar soft part sarcoma is a biopsy, a single tissue sample taken from the tumor through a simple surgical procedure. The tumor's cellular appearance under a microscope enables doctors to distinguish it from other types of cancer.
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- X-rays - a diagnostic test that uses invisible electromagnetic energy beams to produce images of internal tissues, bones and organs onto film. Plain xrays are usually normal in a child with alveolar soft part sarcoma unless the bone adjacent to the tumor is eroded.
- Magnetic Resonance Imaging (MRI) - a diagnostic procedure that uses a combination of large magnets, radiofrequencies and a computer to produce detailed images of organs and structures within the body. This test outlines the extent of the tumor within the bone and joint and identifies the relationship of the tumor to the muscles, nerves and blood vessels.
- Computerized Tomography scan (also called CT or CAT scan) - a diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce cross-sectional images (often called slices)both horizontally and vertically, of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat and organs. CT scans are more detailed that general x-rays. They are used primarily to assess the chest and lung for metastatic tumors.
- Bone scans - a nuclear imaging method to detect bone and metastatic tumors. It will determine if there are abnormalities in other bones. This test does not distinguish between tumor, infection or fractures.
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- Complete blood count (CBC) - a measurement of size, number and maturity of different blood cells in a specific volume of blood
- Blood tests - (including blood chemistries)
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Once alveolar soft part sarcoma has been diagnosed, the tumor is staged. This process indicates whether or not the tumor has spread from its original location, and, if so, how far it has spread. The stage of a tumor suggests which form of treatment is most appropriate, and gives some indication of prognosis.
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Alveolar soft part sarcoma may be localized, meaning it has not spread beyond the tissue where it arose or beyond nearby tissues, or metastatic, meaning it has spread to lungs, brain or other parts of the body.
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Specific treatment for alveolar soft part sarcoma will be determined by your child's physician based on:
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- Your child's age, overall health, and medical history
- Extent of the disease
- The presence or absence of metastasis
- Your child's tolerance for specific medications, procedures or therapies
- How your child's doctor expects the disease may progress
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Treatment for will involve a multidisciplinary team of health professionals that will include pediatric oncologists, surgeons, orthopaedic surgeons, and radiotherapists. Treatment options will vary greatly, depending on your child's individual situation. Your child's physician and other members of your care team will discuss these with you in-depth.
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Surgery is the mainstay of treatment for most soft tissue sarcomas, particularly for localized alveolar soft part sarcoma, which tends to be slow growing and unresponsive to chemotherapy. Surgery includes biopsy of surgical removal of the entire tumor. It is especially important for surgeons to remove wide margins of surrounding healthy tissue, to ensure there are no remaining cancer cells.
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In cases where the tumor is found in the extremities, it may be necessary to remove all or part of the limb. In most cases limb-sparing surgery is used to avoid amputation. The following is a summary of these procedures:
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- Limb-salvage surgery: Often the tumor can be removes along with some surrounding muscle while preserving the limb. The doctors will need to carefully review the imaging studies to make sure that a complete resection can be accomplished while preserving the important nerves and blood vessels necessary to have a functional limb. Usually the bone does not need to be removed. Radiation therapy and/or chemotherapy are sometimes given either before surgery to shrink the tumor, or after surgery to kill remaining cancer cells.
- Amputation: If the tumor is located in a limb and your child's orthopaedic surgeon determines that the tumor cannot be removed because, for example, it involves the nerves and blood vessels, amputation is the only option. During the operation, doctors ensure that muscles and skin form a cuff around the amputated bone. A cast is applied in the operating room which permits a temporary artificial leg (prosthesis) to be applied during the first few post-operative days for walking. Crutches are used for several weeks. As the swelling decreases (10 to 14 days) the patient is fitted for a plastic, temporary socket and prosthesis, which is used for 3 to 4 months until the stump is healed sufficiently to accept a permanent artificial leg. The advantages of an amputation are that it is a simple operation with minimal chances of surgical complication and it definitively removes the local tumor. The functional outcome is good with the modern prostheses available today and with
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If surgery to remove the entire tumor isn't possible or the tumor has metastasized, surgery may be combined with radiation therapy, which uses high energy rays (radiation) from a specialized machine to damage or kill cancer cells and shrink tumors. Because of risks associated with high doses of radiation in young children, radiation is used only if surgery alone is ineffective.
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- Supportive care - any type of treatment to prevent and treat infections, side effects of treatments and complications and to keep your child comfortable during treatment.
- Continuous follow-up care - a schedule of follow-up care determined by your child's physician and other members of you care team to monitor ongoing response to treatment and possible late effects of treatment.
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- The extent of the disease
- The size and location of the tumor
- A presence of absence of metastasis
- The tumor's response to therapy
- The age and overall health of your child
- Your child's tolerance of specific medications, procedures, or therapies
- New developments in treatment
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As with any cancer, prognosis and long-term survival can vary greatly from individual to individual. Prompt medical attention and aggressive therapy are important for the best prognosis. Continuous follow-up care is essential for a child diagnosed with alveolar soft part sarcoma. Side effects of radiation and chemotherapy, as well as recurrence of the disease, can occur in survivors of this condition.
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Children's Hospital and Dana-Farber Cancer Institute are conducting numerous research studies that will help clinicians better understand and treat soft tissue sarcomas.
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- Angiogenesis inhibitors - substances that may be able to prevent the growth of tumors by blocking the formation of new blood vessels that feed the tumors.
- Biological therapies - a wide range of substances that may be able to involve the body's own immune system to fight cancer or lessen harmful side effects of some treatments.
- Chemotherapy - researchers are looking into different chemotherapy drugs that may prove affective on children with alveolar soft part sarcoma.
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