Alveolar soft part sarcoma, or ASPS, is a cancer that can come from different types of soft tissue, such as muscle, fat, or nerves. It may also be called alveolar soft tissue sarcoma, alveolar sarcoma of soft parts, or ASP sarcoma.

ASPS usually starts in the leg, although it can also begin in other parts of the body, including the arms, head, or neck. It can be difficult to find in the early stages because it starts as a painless lump. By the time it is discovered, ASPS often has spread to other places in the body, in particular, the lungs.

ASPS tends to spread early because it creates a network of blood vessels through which cancer cells can travel. Your doctor will monitor your whole body for signs of the cancer spreading.

ASPS is one of the rarest sarcomas. Soft tissue sarcomas make up 1% of all cancers and ASPS makes up only 0.2% to 1% of all soft tissue sarcomas. There are about 80 cases diagnosed per year in the United States.

In adults, ASPS is often found as a painless lump in the leg or buttock. It can also be found in the trunk or arms. In children, ASPS can be found in the head and neck, especially around the tongue or eye socket. In both adults and children, ASPS can be difficult to find early.

Imaging: If you have symptoms of ASPS, your doctor will use imaging scans such as CT or MRI to look at the size of the tumor and where it is in the body. They will also check for signs that the tumor has spread to other parts of the body.

Biopsy: To check if the tumor is ASPS, your doctor will perform a biopsy, taking a small sample from the tumor with a needle. A pathologist will study cells from the sample under the microscope to see what kind of tumor it is.

While ASPS spreads early, it grows much slower than many other sarcomas. This slow growth means that people with ASPS can live for a long time. People with this disease need to be carefully followed by doctors to control the growth and spread of the cancer. Treatment depends on where it starts and where it spreads, which is different for each patient.

Surgery: Surgery is often used to remove the main tumor without harming the healthy tissue.

Radiation therapy: Radiation therapy can be used around the time of surgery. The radiation is aimed at the tumor area to prevent it from growing back after it is removed.

Chemotherapy: Currently, chemotherapy does not work for ASPS.

Targeted therapy: Targeted therapy is intended to prevent the changes in cancer cells that help them grow, divide, and spread. Because chemotherapy does not work for ASPS, researchers are working to make better treatments, such as targeted therapies that have been shown to shrink ASPS tumors.

ASPS is not known to run in families.

Scientists are always working to understand how cancer forms, but it can be hard to prove. We know that in ASPS, chromosomes (the parts of your cells that contain all of your genes) break apart and get put back together in the wrong way. This can cause cells to not function like they should. In ASPS, a gene called TFE3 joins with a region called ASPCR1. Doctors will look for this change in chromosomes to confirm that your cancer is ASPS.

The estimate of how a disease will affect you long-term is called prognosis. Every person is different and prognosis will depend on many factors, such as:

• Where the tumor is in your body
• If the cancer has spread to other parts of your body
• How much of the tumor was taken out during surgery

If you want information on your prognosis, it is important to talk to your doctor. NCI also has resources to help you understand cancer prognosis.

Doctors estimate ASPS survival rates by how groups of people with ASPS have done in the past. Given that there are so few ASPS patients, these rates may not be very accurate. They also don’t consider newer treatments being developed. With this in mind, about 80% of people whose cancer has not spread are alive five years after they are diagnosed with ASPS. Children with ASPS that has not spread have a better chance of survival than adults. If the cancer has spread to other parts of the body, 10% to 40% of people survive five years after diagnosis, depending on whether they have surgery. There are new treatments and clinical trials that show promise for some of these people.