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Soft tissue cancers

Tuesday 30 November, 2010

Reviewed: Annie Angle, cancer nurse (Dip. Oncology Nursing, Royal Marsden, London)

On this page: What is soft tissue sarcoma? ι Types of soft tissue sarcoma ι How common is it? ι Causes ι Symptoms ι Diagnosis

What is soft tissue sarcoma?

Soft tissue is the name for all the supporting tissues in the body, apart from the bones. They include fat, muscle, nerves, deep skin tissue, blood vessels and the tissue that surrounds joints (synovial tissue).

These tissues support and connect all the organs and structures of the body. They are known as connective tissue. A soft tissue sarcoma is a rare type of cancer that forms as a painless lump (tumour) in any one of these soft tissues. They most commonly develop in the thigh, shoulder and pelvis. Sometimes they can grow in the abdomen or chest (trunk).

Types of soft tissue sarcoma

There are over 70 types. They are named after the abnormal cells that make up the sarcoma. The most common type is malignant fibrous histiocytoma (MFH), which is made up of millions of abnormal spindle-shaped cells.

Liposarcoma is the next most common type of soft tissue sarcoma. It's made up of millions of abnormal fat cells. Other types of soft tissue sarcoma include:

leiomyosarcoma and rhabdomyosarcoma, from muscle tissues
angiosarcoma, from blood vessels
Ewing sarcoma and primitive neuroectodermal tumour (PNET)
malignant peripheral nerve sheath tumour (MPNST or PNST)
gastrointestinal stromal sarcoma (GIST) (this is treated differently from other types of soft tissue sarcoma)
stromal sarcoma from supporting tissues
Kaposi's sarcoma of the skin
synovial sarcoma.

How common is soft tissue sarcoma?

Soft tissue sarcoma is not common. Around 226 Victorians develop one of these cancers each year.

Soft tissue sarcoma can develop at any age. Although it's more likely to happen in people over the age of 55, young adults may also be affected. There's almost an equal risk for males and females.

Causes

The causes of most sarcomas are not known. There are several risk factors.

Radiotherapy

There is a very small risk for people who have had radiotherapy. The risk is higher for people who had high doses of radiotherapy at a very young age. Most people who have had radiotherapy in the past will not develop a sarcoma.

Genetic factors

Some rare, inherited conditions can put people at more risk of soft tissue sarcoma. These are:

Von Recklinghausen disease (neurofibromatosis): non-cancerous lumps that develop in the nerves under the skin and over time can turn into sarcoma
Li-Fraumeni syndrome: a genetic condition that increases the risk of many cancers in one family, including soft tissue sarcoma
Retinoblastoma: a rare type of eye cancer mainly found in children.

Most people know if one of these very rare conditions runs in their family, and if so, that they may pass it to their children.

A small number of people develop sarcoma due to genetic changes that happen during their lifetime, rather than inheriting a faulty gene.

Symptoms

Sarcoma usually doesn't cause symptoms in its early stages. As it grows over a period of months, you may develop a painless lump. You may begin to have pain as the lump grows and presses on nerves and muscles. Other symptoms will depend on where in the body the sarcoma is.

Sometimes a soft tissue sarcoma may be mistaken for a benign fatty lump (lipoma) or bruise (haematoma). This can delay tests that would help make the right diagnosis.

Most people who develop a painless lump do not have a sarcoma. It's much more likely to be a less serious condition. However, if you have symptoms that stay for more than 2 weeks you should see your doctor.

Diagnosis

If doctors think you may have a soft tissue sarcoma they will carry out blood tests, x-rays and scans. These tests are needed to rule out other conditions. If the results suggest that you may have sarcoma, your doctor will refer you to a specialist centre.

You may need to have a biopsy. This is the only sure way to diagnose a soft tissue sarcoma. A biopsy means taking a sample of cells from the lump and examining them under a microscope. Your doctor will use a fine needle to do this. You will have local anaesthetic to numb the area before the needle is put into the lump.

A tissue biopsy should only be carried out by a specialist who does them regularly. It's important that the biopsy is done properly in order to minimise the chance of the cancer spreading. It could also affect the type of treatment that you may be able to have.