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.

Although leiomyosarcoma is rare, it is one of the more common types of soft tissue sarcoma in adults. It starts from cells in smooth muscle tissue. Smooth muscles are muscles that we have no control over. They are also called involuntary muscles. They are in the walls of muscular organs like the stomach and heart and, as well as the walls of blood vessels. This means leiomyosarcoma can start anywhere in the body.

Common places for leiomyosarcoma to start are the:

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

Rarely, leiomyosarcoma starts in a large blood vessel.

Leiomyosarcoma usually develops in adults over the age of 50, but it can affect younger people too.

Booklets and resources

Symptoms of leiomyosarcoma

The main symptom of leiomyosarcoma is a lump or swelling that is:

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

Other symptoms may include:

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

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. They are diagnosed by chance when having a test or scan for another reason.

Causes of leiomyosarcoma

The causes of soft tissue sarcomas are not known. There are certain things that can affect the chances of developing a soft tissue sarcoma. These are called risk factors.

Having risk factors does not mean you will get sarcoma, and people without risk factors can still develop it.

Risk factors include having had:

  • radiotherapy to the pelvic area
  • a type of eye cancer called retinoblastoma, caused by a faulty gene.

We have more information about the risk factors and causes of soft tissue sarcoma.

Diagnosis of leiomyosarcoma

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.

The tests you have will depend on the part of the body being investigated.

Tests and scans

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 through the vagina and cervix into the womb. This tube is called a hysteroscope. During the hysteroscopy they examine the womb lining. They usually take tissue samples to look at under a microscope. These are called biopsies.

    You may have this test as an outpatient under a local anaesthetic. Sometimes it is done under a general anaesthetic. A hysteroscopy may be uncomfortable, but it should not be painful. You may be advised to take mild painkillers an hour before the procedure. Some people have vaginal bleeding and mild cramping for a few days after the procedure.

  • 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 (a type of sugar) to measure the activity of cells in different parts of the body.

  • Biopsy

    Your doctor or nurse may take samples of tissue from the tumour. This is called a biopsy. The samples are looked at under a 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 and staging of leiomyosarcoma

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

The stage of a cancer describes its size and whether it has spread from where it started. The grade of the cancer is also included in the staging of leiomyosarcoma.

Knowing the stage and grade of the cancer helps doctors decide on the best treatment for you.

Grading of leiomyosarcoma

The grade is based on:

  • how normal or abnormal the cancer cells look, called differentiation
  • how quickly the cancer cells are dividing to make new tumour cells, called the mitotic rate
  • whether there is any dying tissue in the tumour, called necrosis.

The cancer cells will be given one of 3 grades:

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

Staging of leiomyosarcoma

Different staging systems may be used. This can depend on where in the body the leiomyosarcoma started. The most commonly used systems are the TNM staging system and a number staging system.

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 lungs or liver. This is called metastatic or secondary cancer.

Doctors put numbers after the T, N, and M giving 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 4 stages:

  • Stage 1 may be under or over 5cm, is grade 1 and has not spread.
  • Stage 2 is bigger, and may be either grade 2 or grade 3, but has not spread to nearby lymph nodes or other parts of the body.
  • Stage 3 is at least 5cm but can be over 15cm. It may be grade 2 or grade 3, but it has not spread to lymph nodes or other parts of the body.
  • Stage 4 can be any size and any grade. It has spread into nearby lymph nodes or to other parts of the body.

Treatment for leiomyosarcoma

A team of specialists meet to discuss the best possible treatment plan for you. This is called a multidisciplinary team (MDT). 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.

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

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

Your doctor and nurse will talk to you about the best treatment for you. They can talk to you about things to think about when making treatment decisions.

The main treatments for leiomyosarcoma are surgery and radiotherapy. Sometimes chemotherapy is used as well.


Surgery is the main treatment for leiomyosarcoma. The aim is to remove all of the cancer and an area of healthy tissue around it. This area is called a margin. The type of operation you have will depend on where the leiomyosarcoma started.

For example, if you have a leiomyosarcoma of the womb you will have a total hysterectomy. Your surgeon may also remove the ovaries and fallopian tubes.

If the leiomyosarcoma is early-stage and you have not been through the menopause, it may be possible to keep your ovaries. This means you will still produce hormones and will not go through menopause straight away.

We have more information about surgery for soft tissue sarcoma.

Other treatments

  • Radiotherapy

    You may have radiotherapy after surgery to reduce the chance of the cancer coming back. Radiotherapy is usually given if the tumour is high-grade. It is sometimes given before surgery instead of afterwards.

  • Chemotherapy

    Chemotherapy is used less often than radiotherapy. It is sometimes used before or after surgery, or if the cancer cannot be removed with surgery. It may also be used if the cancer has come back or spread to other parts of the body.

You might have some treatments as part of a clinical trial.


After leiomyosarcoma treatment

Follow up

You will have regular check-up appointments 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. If you have any new symptoms between appointments, let your doctor or nurse know.

Late effects

Sometimes side effects may continue or develop months or years after treatment. These are called late effects. Your cancer doctor or specialist nurse will explain more about any possible late side effects and what might help.

Body image

The effects of your treatment might affect how you think and feel about your body. Talk to your nurse if you have concerns about your body image. 

Sex and fertility

Cancer and its treatment can sometimes have an effect on your sex life. If you are worried about this talk to your doctor or nurse. You can read about things that may help in our information on cancer and sex.

Some cancer treatments may affect your fertility. If you are worried about your fertility it is important to talk with your doctor before you start treatment. We have more information about:

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 well-being and help your body recover.

Related pages

Getting support

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

Organisations such as Sarcoma UK can provide information and support. Cancer52 works to improve the quality of life for people with rare cancers. Macmillan is also here to support you. If you would like to talk, you can:

About our information

  • References

    Below is a sample of the sources used in our leiomyosarcoma information. If you would like more information about the sources we use, please contact us at cancerinformationteam@macmillan.org.uk

    Gronchi A, Miah AB et al. Soft tissue and visceral sarcomas: ESMO-EURACAN-GENTURIS Clinical practice guidelines for diagnosis, treatment and follow-up. Annals of Oncology, 2021; 32, 11, 1348-1365 [accessed May 2022]

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by senior medical editor Fiona Cowie, Consultant Clinical Oncologist.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

The language we use

We want everyone affected by cancer to feel our information is written for them.

We want our information to be as clear as possible. To do this, we try to:

  • use plain English
  • explain medical words
  • use short sentences
  • use illustrations to explain text
  • structure the information clearly
  • make sure important points are clear.

We use gender-inclusive language and talk to our readers as ‘you’ so that everyone feels included. Where clinically necessary we use the terms ‘men’ and ‘women’ or ‘male’ and ‘female’. For example, we do so when talking about parts of the body or mentioning statistics or research about who is affected.

Date reviewed

Reviewed: 01 August 2022
Next review: 01 August 2025
Trusted Information Creator - Patient Information Forum
Trusted Information Creator - Patient Information Forum

Our cancer information meets the PIF TICK quality mark.

This means it is easy to use, up-to-date and based on the latest evidence. Learn more about how we produce our information.