What is leiomyosarcoma?

Leiomyosarcoma is a type of soft tissue sarcoma.

Sarcomas are cancers that develop from cells in the supporting or connective tissues of the body, such as muscle, fat, nerves, blood vessels, bone and cartilage.

Leiomyosarcoma is one of the more common types of soft tissue sarcoma to develop in adults. It starts from cells in a type of muscle tissue called smooth muscle.

Smooth muscles are muscles that we have no control over (involuntary muscles). They are in the walls of muscular organs like the heart and stomach, as well as in the walls of blood vessels throughout the body. This means leiomyosarcoma can start anywhere in the body.

Common places are the:

  • tummy area (abdomen)
  • area in the back of the abdomen (retroperitoneum)
  • walls of the womb (uterus).

They are sometimes found in the deep, soft tissues of the legs or arms, but this is less common.

Leiomyosarcoma is rare. Every year, about 600 people in the UK are diagnosed with leiomyosarcoma. It usually develops in adults, particularly in older people.

Most people with leiomyosarcoma are over the age of 50.

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Symptoms of leiomyosarcoma

The main symptom to be aware of is any lump or swelling that is:

  • getting bigger
  • bigger than 5cm (2in) – about the size of a golf ball
  • painful or tender.

Other symptoms depend on where it is in your body. These may include:

  • tummy (abdominal) discomfort or bloating
  • blood in or on your poo (stools), or bleeding from the back passage (rectum)
  • bleeding from the vagina in women who have had the menopause
  • a change in periods for women who have not yet had the menopause.

Most soft tissue lumps are not cancer. But if you notice any of these symptoms, get them checked by your GP.

Some people do not have symptoms, but are diagnosed by chance when having a test or scan done for another reason.

Causes of leiomyosarcoma

The causes of leiomyosarcoma are unknown, but research is going on to try to find out more.

Soft tissue sarcomas may develop in an area that has previously been treated with radiotherapy for another type of cancer.

The sarcoma does not usually develop until at least 5 to 10 years after the radiotherapy treatment.

Exposure to some types of chemical may increase the risk of developing some sarcomas. The chemicals include:

  • vinyl chloride – this is used for making plastics
  • some types of weed killer (herbicides)
  • dioxins – these are waste products made during the manufacture of chemicals and fertilisers.

Leiomyosarcoma diagnosis

Tests and diagnosis

If you have symptoms, you usually start by seeing your GP, who will examine you. If your GP is not sure what the problem is, or thinks your symptoms could be caused by cancer, they will refer you to a specialist doctor at the hospital.

You may also have blood tests to check your general health and the number of cells in your blood (blood count).

At the hospital, the specialist doctor will ask you about your symptoms and your general health. They will also examine you and arrange some of the following tests.

Possible tests

The tests you have will depend on the part of the body being investigated. You may have had some of these tests already.

  • Hysteroscopy

    A hysteroscopy is used to diagnose problems in the womb. The doctor or nurse passes a small, thin tube with a light and camera at the end (hysteroscope) through the vagina and cervix into the womb. They may take tissue samples (biopsies) to look at under a microscope. You may have this test as an outpatient under a local anaesthetic, but sometimes a general anaesthetic is needed. You may be advised to take mild painkillers an hour before the procedure.

    A hysteroscopy may be uncomfortable, but it should not be painful. Some women may have vaginal bleeding and mild cramping for a few days after the procedure. You can take mild painkillers to help with this.

  • Ultrasound scan

    An ultrasound scan uses soundwaves to make a picture of the inside of the body. You may have this test to look for a suspected cancer in the tummy (abdomen) or in a limb. If a womb sarcoma is suspected, the ultrasound may be done from inside the vagina. This is called a transvaginal ultrasound scan.

  • CT scan

    A CT scan takes a series of x-rays, which build up a 3D picture of the inside of the body.

  • MRI scan

    An MRI scan uses magnetism to build up a detailed picture of areas of your body.

  • PET scan

    A PET scan uses low-dose radioactive glucose to measure the activity of cells in different parts of the body.

  • Biopsy

    A biopsy means the doctor takes a sample of cells from the area to be checked for cancer under the microscope. We have more information about having a biopsy in our information about diagnosing soft tissue sarcoma. Your doctor or specialist nurse will give you more information.

Our cancer support specialists or your specialist doctor or nurse can give you information about any tests we do not explain here.

Waiting for test results can be a difficult time, we have more information that can help.

Grading leiomyosarcoma

The grade of a cancer gives an idea of how quickly it might grow. Doctors look at a sample of the cancer cells under a microscope to find the grade of the cancer.

Grading of soft tissue sarcomas can sometimes be difficult. The grade is based on three factors:

  • how normal or abnormal the cancer cells look – this is called differentiation
  • the rate the cancer cells are dividing at to make new tumour cells – this is called the mitotic rate
  • if there is any dying tissue in the tumour – this is called necrosis.

There are three grades:

  • G1 – the cancer cells look very much like the normal cells, they are usually slow-growing and are less likely to spread.
  • G2 – the cancer cells look different to normal cells and are growing slightly faster.
  • G3 – the cancer cells look very different to normal cells, may grow more quickly, and are more likely to spread.

The sarcoma may be described as being low grade (G1) or high grade (G2 or G3).

Staging leiomyosarcoma

The stage of a cancer describes its size and whether it has spread from where it started. Knowing the stage helps doctors decide on the best treatment for you.

Different staging systems may be used. Two of the most commonly used systems are the TNM staging system and a number staging system. The staging systems for leiomyosarcoma vary depending on where in the body it started.

TNM staging

TNM stands for Tumour, Node and Metastasis.

  • T describes the size of the tumour.
  • N describes whether the cancer has spread to the lymph nodes.
  • M describes whether the cancer has spread to another part of the body, such as the liver or lungs (known as metastatic or secondary cancer).

Doctors put numbers after the T, N, and M that give more details about the size and spread of the cancer.

Number staging

Information from the TNM system and the grade of the cancer can be used to give a number stage.

Leiomyosarcoma is divided into four stages:

  • Stage 1 – the cancer is smaller than 5cm, low grade and has not spread.
  • Stage 2 – the cancer is bigger, may be either low or high grade and has not started to spread.
  • Stage 3 – the cancer is high grade, but it has not spread.
  • Stage 4 – the cancer has started to spread into nearby lymph nodes or other parts of the body.

Treatment of leiomyosarcoma

The treatment you have depends on a number of things, including:

  • your general health
  • where the cancer started
  • the size of the tumour
  • the grade of the cancer.

The results of your tests help your doctor plan the best type of treatment for you. They then discuss this with you.

Because sarcomas are rare cancers, you should be referred to a specialist unit for treatment. This may mean you need to travel further to have your treatment. You may be offered some treatments as part of a clinical trial.

Surgery is the main treatment for small and localised leiomyosarcomas. It may be followed by radiotherapy to reduce the chance of the cancer coming back.

Radiotherapy is sometimes used before surgery to shrink a larger tumour and make it easier to remove.

Chemotherapy is also used for some leiomyosarcomas. It is mainly used:

  • if the cancer has come back (recurred)
  • if the cancer has spread (advanced or metastatic cancer)
  • if the cancer cannot be removed with surgery
  • after surgery, to try to reduce the chance of the cancer coming back.

We have more information about treating sarcomas in our general information about soft tissue sarcomas.

After leiomyosarcoma treatment

Follow up

You will have regular check-ups at the hospital. Your doctor will examine you and ask about any side effects or symptoms. You will also have blood tests. You may also have an x-ray of your chest or CT scan.

Let your doctor know if you have any new symptoms between appointments.

Your feelings

Everyone has their own way of dealing with illness and the different emotions they experience. You may find it helpful to talk things over with family and friends or your doctor or nurse.

Macmillan is also here to support you. If you would like to talk, you can:

Sarcoma UK offers support and information to anyone affected by sarcoma.

Well-being and recovery

Even if you already have a healthy lifestyle, you may choose to make some positive lifestyle changes after treatment.

Making small changes such as eating well and keeping active can improve your health and wellbeing and help your body recover.

Reviewed: 30 November 2019
Reviewed: 30/11/2019
Next review: 01 May 2022
Next review: 01/05/2022

This content is currently being reviewed. New information will be coming soon.