A leiomyosarcoma belongs to a group of cancers called soft tissue sarcomas. Sarcomas are cancers that develop in the supporting or connective tissues of the body (such as muscle, fat, nerves, blood vessels, bone, and cartilage). They are rare. Approximately 1,200–2,000 people will be diagnosed with a sarcoma each year in the UK. Most people with leiomyosarcoma will be over the age of 50.


People with early leiomyosarcoma often do not have any symptoms. Most leiomyosarcomas are diagnosed after a person develops symptoms. These may include: 

  • A lump or swelling 
  • Abdominal discomfort or bloatedness 
  • Swelling or pain in any area of the body
  • Bleeding from the vagina in women who have had their menopause, or a change in periods for women who have not yet had the menopause.

If you notice any of the above, contact your GP, but remember that these symptoms can be caused by many things.


The exact cause of leiomyosarcoma is unknown, and research is ongoing to try and find out as much as possible about these tumours. Very rarely, soft tissue sarcomas may also occur in an area that has previously been treated with radiotherapy for another type of cancer. The sarcoma will not usually develop until at least ten years after the radiotherapy treatment. Improvements in targeting radiotherapy mean that the risk of developing a sarcoma after radiotherapy treatment is very small. Exposure to some types of chemicals may increase the risk of a person developing some sarcomas. The chemicals include vinyl chloride, which is used for making plastics, some types of herbicides (weedkillers) and dioxins.


Usually you begin by seeing your family doctor (GP), who will examine you. You will be referred to a hospital specialist for any tests that may be necessary and for expert advice and treatment. The doctor at the hospital will take your full medical history, do a physical examination and take blood samples to check your general health. The following tests are commonly used to diagnose a leiomyosarcoma. The tests you have will depend upon the part of the body that is being investigated. You may have had some of these tests already. If you are having investigations other than those listed, our nurses can give you further information.


The treatment for leiomyosarcoma depends on a number of things including your general health, and the size and position of the tumour within the body. The results of your tests will help your doctor to decide on the best type of treatment for you. They can then discuss this with you. The usual treatment for a leiomyosarcoma is surgery, wherever possible, to remove the tumour. This may be followed by radiotherapy to reduce the chance of the cancer coming back. Chemotherapy is also used for some leiomyosarcomas. This may be to try to reduce the chances of the leiomyosarcoma coming back, or to treat a leiomyosarcoma that has spread. Treatment of sarcomas is discussed in more detail in our general information about soft tissue sarcomas.