Sarcoma
What is sarcoma?
Sarcoma is the name given to cancers that arise from the bones and soft tissues, including fat, muscle and blood vessels. Bone sarcomas usually occur in children and adolescents, while soft tissue sarcomas are more common in adults.
What is different about sarcoma?
Sarcomas are very rare compared to other types of cancer. There are more than 1 million new cancer cases each year. Just 12,000 of those are sarcomas. Sarcomas make up just 1% of cancer cases in adults.
There is also a wide variation in types of sarcoma. There are more than 70 subtypes of soft tissue sarcoma, some of which are very slow growing and almost benign, whereas others grow rapidly and are very aggressive. Some of the more common subtypes are:
- Liposarcoma – originates from fat
- Leiomyosarcoma – smooth muscle
- Rhabdomyosarcoma – skeletal muscle
- Angiosarcoma – blood vessel
- Malignant peripheral nerve sheath tumor – covering around the nerves
- Synovial sarcoma – unknown tissue origin
- Undifferentiated pleomorphic sarcoma – unknown tissue origin
- Desmoid tumor – unknown tissue origin, likely scar tissue
- Dermatofibrosarcoma protuberans – unknown tissue origin, likely from the skin
Knowing the exact subtype is important because it has implications for how the tumor will behave and how it will respond to different types of treatment. For example:
- Desmoid tumor – does not spread
- Alveolar soft parts sarcoma – commonly spreads to the brain
- Leiomyosarcoma – can spread to the skin
- Myxoid liposarcoma – can spread to other fat-bearing areas
- Well-differentiated liposarcoma – can have a distinct focal area of high-grade disease (dedifferentiated) within a larger low-grade tumor
- Malignant peripheral nerve sheath tumor – can occur in patients with a hereditary syndrome called neurofibromatosis
Because sarcomas are so rare and have such a wide range of subtypes, it’s important to see a sarcoma specialist who has extensive experience with these kinds of tumors.
How and where does sarcoma appear?
Sarcoma can start as a new, painless lump. Pain can occur (for example, if the tumor is compressing a major nerve), but it’s not common. Sometimes sarcomas do not cause any symptoms and are detected when a patient sees a doctor for other issues. In general, any new lump or mass should be checked out.
Sarcoma can occur anywhere in the body. The most common location is in the legs and arms. About 20% of sarcomas appear in the back of the abdomen, which is also known as the retroperitoneum. Sarcomas in this location often grow to a very large size before they are detected.
What causes sarcoma?
The cause for the vast majority of sarcoma subtypes is unknown. Some sarcomas may be hereditary, and some factors like radiation treatment for another cancer can raise a person’s risk for developing specific subtypes of sarcoma. Importantly, current research suggests that sarcoma is not linked to smoking, diet, obesity or specific lifestyle habits.
How is sarcoma diagnosed?
If you suspect you have a soft tissue sarcoma, your doctor may have you undergo an MRI or CT scan, followed by a biopsy. There are two types of biopsy:
- Core biopsy – A small amount of tumor tissue is removed using a wide needle. This can be done as a minor procedure by a radiologist (sometimes guided by ultrasound or CT scan/MRI).
- Incisional biopsy – Part of a tumor is removed through a minor surgery. This minor procedure is performed by a surgeon, and is often done if a needle biopsy doesn’t provide enough information for a diagnosis.
A pathologist looks at the biopsy tissue under a microscope to look for cancer cells to make the diagnosis. Sarcoma can be hard to diagnose, so it’s important to have the biopsy reviewed by a trained sarcoma pathologist. Diagnosing the correct subtype of sarcoma is key to building the right treatment plan.
What tests are necessary after a sarcoma diagnosis?
Depending on the subtype, further studies may be needed to determine if the sarcoma has spread. This often includes a CT scan of the chest, as the most common location of spread is to the lungs. Occasionally, a whole-body PET scan is done to simultaneously look at the lungs and other potential sites, such as the liver. A PET scan also provides additional information about tumor activity. This can be used to monitor response to treatment, for example, before and after drug therapy.
What is the treatment for sarcoma?
For sarcomas that have not spread, surgery is the main treatment. The surgeon works to remove the tumor completely while still saving critical organs and structures (such as blood vessels and nerves) if possible. Depending on the case, a care team may also recommend chemotherapy or radiation therapy to ensure the best possible outcome.
Patients with sarcomas that have already spread or that cannot be removed by surgery usually undergo drug therapy. This includes traditional chemotherapy. In the last few years, newer drugs have become available for sarcoma, including better targeted therapies and immunotherapy.
After treatment, what is my prognosis?
Sarcoma cases vary so much that each patient will have a different prognosis. Your surgeon will take time to talk to you about your sarcoma subtype, your treatment plan and what you can expect.
After treatment, what follow-up is needed?
Unfortunately, most sarcomas can come back. It’s important to have regular follow-up visits with a sarcoma specialist and get MRI or CT scans, as recommended, for a minimum of two or three years following treatment. In some cases, follow-up scans may be recommended for a longer period of time or indefinitely. If your specialist sees no evidence of disease over time, you may transition to ultrasound or X-rays. Since each case is different, your care team will design a unique plan just for you and keep updating it based on your scan results.
What else is important to know about sarcoma?
Because it is so rare, the treatment of sarcoma should be done at a specialized center with physicians who have experience and expertise in this specific disease. Research demonstrates that patients have better outcomes when seen by sarcoma specialists. You will most likely work with a team of experts in different disciplines, including surgery, medical oncology and radiation oncology.
Surgery for sarcoma is also best performed by a surgical oncologist (cancer surgeon) specifically trained to manage this frequently challenging disease. A sarcoma specialists deep knowledge of the disease is crucial to getting the right care.