Soft Tissue Sarcoma overview

What is soft tissue sarcoma?

Cancer happens when cells become abnormal and keep growing. Soft tissue sarcomas are a group of cancers. They start in areas that support, connect, surround and protect the body. This includes:

• fat
• muscles
• tendons and ligaments
• lymph vessels
• blood vessels
• nerves, and
• deep skin tissue.

Soft tissue sarcomas often form a painless lump. The lump may become painful if it grows, but most lumps in the body are not cancer.

Soft tissue sarcomas can grow into nearby tissue or spread (metastasise) to other parts of the body. Sarcoma that starts in the bones, also called primary bone cancer or Ewing sarcoma, may be diagnosed and treated differently to other soft tissue sarcomas.

Soft tissue sarcoma can grow almost anywhere, but it’s more common in the areas shown below.

Types

There are many different soft tissue sarcomas. The more common ones are listed here. Sarcomas are usually named after the type of cell where the cancer started, or the part of the body where they are found.

• undifferentiated pleomorphic sarcoma (UPS) – mix of cells with different sizes and shapes
• gastrointestinal stromal sarcoma (GIST) – from nerve cells in the stomach; treated differently to other soft tissue sarcomas
• liposarcoma – from fat cells
• leiomyosarcoma – from muscle tissues (e.g. in blood vessel walls or the uterus)
• rhabdomyosarcoma – from muscle tissues; more common in children and young adults
• angiosarcoma – from blood and lymph vessels
• malignant peripheral nerve sheath tumour (MPNST) – from the cells that cover nerves; also called neurofibrosarcoma
• fibrosarcoma and myxofibrosarcoma – from fibrous connective tissues
• sarcomas in stromal tissue  – from supporting tissues
• Kaposi sarcoma – from skin cells; or may be in the lower legs
• spindle cell sarcoma – made up of many spindle-shaped cells
• synovial sarcoma – from connective tissues; often found in arms, legs, feet and around joints
• pleomorphic dermal sarcoma (PDS) – most common on the surface of sun-damaged skin in older people
• epithelioid hemangioendothelioma (EHE) – from cells in the walls of blood vessels

Risk factors

The cause of sarcoma is not always known. Factors that may increase your risk of certain types of soft tissue sarcomas include:

• Radiation therapy – People who had radiation therapy (also called radiotherapy) have a slightly higher risk of sarcoma. But most people who have radiation therapy won’t get soft tissue sarcoma.
• Inherited conditions – Some rare conditions that run in families may increase your risk of sarcoma. These include neurofibromatosis (NF), Li-Fraumeni syndrome, retinoblastoma, tuberous sclerosis and Werner syndrome. Most people will know if one of these very rare conditions runs in their family.
• Chemical exposure – Being exposed to vinyl chloride (used in making plastic), dioxins, and some high-dose herbicides (weedkillers) may increase your risk of sarcoma.
• Lymphoedema – Swelling from a build-up of lymph fluid (lymphoedema), especially over a long period of time, may increase your risk of angiosarcoma.
• Immunosuppression – People with a weak immune system, like those taking medicine after an organ transplant or for an autoimmune disease, are at a higher risk of Kaposi sarcoma.

Symptoms

Soft tissue sarcomas often don’t cause any symptoms at first. As they get bigger, you may notice a painless lump. It may become painful if it presses on sensitive areas, such as nerves or muscles.

Knowing whether something is a harmless lump or a soft tissue sarcoma is often difficult without proper testing. Some sarcomas are mistaken for a benign fatty lump (lipoma) or bruise (haematoma).

Talk to your doctor if you notice a lump that doesn’t go away or gets bigger over time. Some less common sarcomas may cause skin changes, or tummy symptoms such as feeling sick, not being hungry, or blood in your poo.

Diagnosis

Your doctor will ask about your medical history and do a physical examination to feel for a lump. They may also arrange tests or refer you to another specialist for testing. Common tests include:

• CT (computerised tomography) scan – This scan creates 3D pictures of the inside of your body. You may first have an injection of dye (called contrast) into a vein, to make the pictures clearer. Then, you lie still on a table that moves through a large, doughnut-shaped scanner. This is a painless scan and usually takes about 10 minutes, but the appointment may be longer if contrast is used.
• MRI (magnetic resonance imaging) scan – Like a CT, this scan creates 3D pictures of the inside of your body. You lie on a table that slides into a long metal tube, which is open at both ends. An MRI takes 30-90 minutes. Some people may feel anxious in the narrow space. You may or may not need an injection of contrast for this scan.
• X-ray – This painless test takes a few minutes and may be used to check your chest, lungs, abdomen or a limb. It gives less detail than other scans.
• Ultrasound scan – This scan creates pictures of the inside of your body. It’s used to check lumps in the arm, leg, chest or abdomen. It’s painless, uses no radiation, and is done with a handheld probe that moves over the skin.
• PET (positron emission tomography) scan – This scan helps show if sarcoma has spread to other parts of the body. You’ll be injected with a small amount of harmless radioactive solution. You sit quietly for about 30–60 minutes so the solution can move through your body. The painless scan then takes about 30 minutes in a machine that is open at both ends. The radiation leaves your body after a couple of hours.

Staging sarcoma

Staging is the process doctors use to describe how far the cancer has grown, whether it has spread and the risk of it coming back. The stage is based on the below.

• Grade – describes how abnormal the cells look under a microscope. Most sarcomas are graded from 1 to 3 (low, intermediate, high). A higher grade means the sarcoma is likely to grow and spread more quickly.
• Size – describes the size of the tumour from imaging scans and how far it may have spread (e.g. to the lungs)
• Location – describes where in the body the tumour is, for example, in a limb or the abdomen. Superficial sarcomas in or just under the skin have a lower risk. Deep sarcomas within muscles or areas such as the abdomen usually have a higher risk.

Knowing the stage helps doctors plan the best treatment for you. How the stage is described may vary depending on the type of sarcoma and where in the body it is. Talk to your doctor about what the stage means and how if affects your treatment.