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Alveolar soft part sarcoma is a cancer that starts in the body's soft tissues, such as muscle, fat or nerves. While it can appear anywhere, it is most often found in the legs of young adults and in the head or neck area of children. It is often slow-growing, but it also tends to spread to other parts of the body, like the lungs, early on through the blood vessels.
It gets its name because the cancer cells look like tiny air sacs, which are called alveoli, in the lungs when viewed under a microscope. Alveolar soft part sarcoma is sometimes just called ASPS. It may also be called alveolar soft tissue sarcoma or alveolar sarcoma of soft parts.
Alveolar Soft Part Sarcoma Care Tailored to You
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Symptoms and Signs
The most common sign of alveolar soft part sarcoma is a painless lump that grows slowly. Because it usually doesn’t hurt, the disease can be hard to diagnose in the early stages. In adults, these lumps are usually found in the deep tissues of the legs or buttocks, and can cause symptoms like unusual bleeding. In many cases, because there are few early signs, alveolar soft part sarcoma often isn’t detected until it has already spread and causes problems in other organs.
Causes and Risk Factors
Scientists are still learning why alveolar soft part sarcoma forms in the first place, but they know it is caused by a genetic error. In the case of alveolar soft part sarcoma, two chromosomes break and join back together the wrong way. This mistake causes cells to grow when they shouldn't.
It’s important to know that ASPS is not known to run in families, and it is not linked to past radiation treatments like some other cancers are.
Alveolar soft part sarcoma is most common in people under age 30, and it is slightly more common in females.
Alveolar Soft Part Sarcoma Prevalence: By the Numbers
Alveolar soft part sarcoma is one of the rarest sarcomas. Approximately 80 cases of this cancer are diagnosed a year in the U.S.
While soft tissue sarcomas make up 1% of all cancers, ASPS makes up just 0.2% to 1% of all soft tissue sarcomas.
Alveolar Soft Part Sarcoma Care Team
At Fred Hutch, we offer comprehensive treatment from a team of experts who specialize in soft tissue sarcomas and bone cancers.
Learn more about sarcoma specialists at Fred Hutch.
Diagnosing Alveolar Soft Part Sarcoma
To diagnose ASPS, a patient will have a physical exam. A physician will also order tests, including imaging tests like CT scans or MRIs to see the size of the tumor and check if it has spread (metastasized). The most important part of the diagnosis is a biopsy, where a sample of the tumor is removed so it examined in a lab. All this information is key to understanding the stage of the disease. Physicians will also order tests to look for the specific gene change that happens in alveolar soft part sarcoma to confirm the diagnosis.
Learn more about diagnosing and staging sarcoma.
Treating Alveolar Soft Part Sarcoma
The main treatment for alveolar soft part sarcoma is surgery to remove the tumor while trying to avoid removing as much of the surrounding healthy tissue as possible. A physician may also recommend radiation therapy before or after surgery to help keep the cancer from returning.
Unlike other types of sarcoma, standard chemotherapy is not used to treat ASPS. Instead, researchers are finding success with targeted therapy, which uses medicines designed to block the specific signals that help ASPS cancer cells multiply. Because it grows slowly, patients need to be followed closely by their care team after they are treated, to detect and manage any recurring cancer.
Learn more about treating sarcoma.