What Is Alveolar Soft Part Sarcoma

Alveolar soft part sarcoma is a rare cancer of the soft tissue cancer family called sarcomas. It commonly arises as a painless lump in the lower extremities or in the head and neck region.¹ This cancer can occur in adults or children but is more common between late twenties and early thirties.¹ Complete surgical removal is the treatment of choice, and the outcome is generally poor.

Overview

Alveolar soft part sarcoma is a name derived partly from its appearance in the microscopic view.² Alveoli are the air sacs in the lung, and this tumour bears some resemblance to them when viewed under the microscope. As the name implies, alveolar soft part sarcoma arises from soft or supporting tissues of the body and usually presents as a painless lump.1 It can be slow growing, but it is still a cancer with a poor outcome. Surgical removal is the mainstay of treatment. Sometimes, radiation and additional treatment like targeted therapy can also be used. A specific genetic defect is a key feature of this cancer.¹

Who gets alveolar soft part sarcoma?

Anyone can get alveolar soft part sarcoma, but it is seen more commonly in younger populations. The commonest age range to have this cancer is reported to be between 25 and 35 years.¹

In addition, those who are Assigned female at birth (AFAB) are said to get this cancer more than those who are Assigned male at birth (AMAB).¹

How do you know if you have alveolar soft part sarcoma?

The main issue with Alveolar soft part sarcoma is that it grows very slowly at first, causing no symptoms. In the later stages of the cancer, a person may notice a painless lump or get some symptoms due to compression of nearby structures. The symptoms vary depending on the location. 

In adults, the most common location for the tumour tends to be the trunk and lower extremities, while in children, it’s usually in the head and neck region.

Some possible symptoms include:¹

• Pain in the lower extremities
• Discomfort in the eye or nose if the cancer is in the head and neck region
• Bleeding from the rectum or vagina, if it's in the larger intestines or vagina, respectively

What are the physical signs of alveolar soft part sarcoma?

These again depend on the location:

• If it is in the lower extremities, it is usually a painless lump.
• In the head and neck region, it can cause some obstruction to facial features - eg proptosis or, in other words, swelling and bulging of the eyeball if the tumour grows behind the eye socket.

Can alveolar soft part sarcoma spread to other parts of the body from its original site?

It is reported that when this cancer is detected, it has often spread to other organs².

This is because alveolar soft part sarcoma is a slow-growing cancer and hardly causes pain. Therefore, it takes time for the lump to come to the notice of the patient. Hence, by the time it is noticed and detected, the cancer has already spread to other organs. The most common organs to spread include lung and brains.²

How do you diagnose alveolar soft part sarcoma?

• Imaging: When someone presents with a lump or suggestive symptoms, the doctor will order a CT scan or MRI scan to check the tumour.¹ Alveolar soft sarcoma often has a lot of blood vessels running through it.5 This can often be visualized on the scans. In fact, imaging can rarely mistake a tumour for defective blood vessels.¹
• Biopsy: This means sampling a piece of the cancer, processing it in the laboratory and looking at it under the microscope. The sample will then require some further testing called Immunohistochemistry. This includes a special staining method that highlights particular cancer cells, helping to diagnose alveolar soft part sarcoma.
• Genetic abnormality test: The genetic abnormality in the alveolar soft part sarcoma causes changes in the cells that can be partly detected by immunohistochemistry.¹ For confirmation of the diagnosis, the genetic abnormality is tested with a genetic laboratory test.

How is the genetic abnormality tested?

The abnormality in the alveolar soft part of the sarcoma is a translocation.¹ This means a mix up of material between units that carry our DNA called chromosomes. 

One of the ways to detect this type of genetic defect is by a method called FISH or fluorescence in situ hybridisation. This test is performed on a sample of the cancer after some processing. The test will light up and show the mixed-up parts of genetic material.

How do you treat alveolar soft part sarcoma?

Treating Alveolar Soft Part Sarcoma often involves a combination of approaches.

Surgery is typically the mainstay of treatment, where surgeons aim to remove the tumour whenever possible. However, due to the nature of this cancer, complete removal isn't always feasible. In such cases, radiation therapy may be used to target any remaining cancer cells. Additionally, some patients may receive targeted therapy to help control the disease's progression, although these options are still being studied for their effectiveness.² Immune checkpoint inhibitors have also gained a reputation for being effective.⁶ 

Managing this cancer requires a personalized approach, and patients often work closely with a medical team to determine the best treatment plan based on the tumour size, location, tumour stage and overall health. Regular follow-ups and ongoing care are crucial to monitor and address any potential changes or recurrences.

What is the outcome or prognosis for alveolar soft part sarcoma?

The prognosis of Alveolar Soft Part Sarcoma can vary widely depending on several factors. The stage of the cancer is the most important factor.² 

Alveolar soft part sarcoma is a rare cancer, and while it tends to grow slowly, it has a tendency to spread to other parts of the body, which can make it challenging to treat. However, with early diagnosis and appropriate treatment, some people with this cancer have achieved long-term remission. It's important to note that alveolar soft part sarcoma outcomes can differ from one person to another. 

Regular medical follow-ups, a strong support system, and ongoing research into new treatment options play key roles in managing alveolar soft part sarcoma and improving the chances of a positive outcome.

Some data reports that if this cancer is localized to a particular area of the body, the survival can be about 87% at 5 years.² If it has spread to other areas, the survival is reported to be about 20%.²

Can the alveolar soft part of the sarcoma be completely cured?

In most patients, this cannot be completely cured.⁶  However, with effective surgical resection and other additional therapy, it is possible to control the disease to some extent.

Does the disease run in the family, in other words is it genetically inherited?

This cancer is not known to run in families.⁵ However, the disease is caused by a defect in the genetic material that occurs in an individual.⁴ There is a mix-up or exchange of genetic material within two different chromosomes. It does not mean that the defect is carried into generations.

How can I prevent Alveolar soft part sarcoma?

There is no definitive cause found yet for this cancer. Therefore it is not possible to take steps to avoid it. Noticing any symptoms described above and bringing them to medical attention is the best possible thing to do for a better outcome. In fact,  this is the case for many cancers where early detection helps to improve its outcome.

What other conditions can resemble alveolar soft part sarcoma?

Alveolar soft part sarcoma is a cancer with many blood vessels. Therefore, on scans, it can rarely appear as a cancer of blood vessels or as a defective growth of blood vessels. 

Under the microscopic vision, some cancers like clear cell carcinoma of the kidneys can appear slightly similar.¹ However further testing called immunohistochemistry can be done to differentiate these confidently. 

What will it be like living with Alveolar soft part sarcoma?

Living with alveolar soft part sarcoma can be a challenging journey, even for those familiar with medical terminology. It is a rare type of cancer that often affects young adults and tends to develop in soft tissues, making it particularly unpredictable. Coping with this cancer often involves navigating a range of emotions, treatment options, and lifestyle adjustments.

Summary

Alveolar soft part sarcoma is a rare cancer that belongs to cancers of soft tissue. Cancer can occur in anyone, but it is more common in the age range of 25 to 35 years. The cancer is caused by a special defect in genetic material.  Alveolar soft part sarcoma usually occurs in the lower extremities or in the head and neck region. It can be diagnosed by sampling the cancer and seeing it under the microscope. Testing for the genetic defect is confirmatory. The best treatment is complete surgical removal. However, this cancer is often hard to cure completely, but it can be controlled to some extent.