Definition and Overview

Leiomyosarcoma is a type of soft tissue sarcoma that develops in smooth muscle cells. These cells make up involuntary muscles or those that contract without conscious control. Examples are those found on the skin, walls of the blood vessels, uterus, stomach, and intestines.

Leiomyosarcoma, which is the malignant counterpart of leiomyoma, is very rare accounting for just 8% of all soft tissue sarcomas, which are in themselves relatively rare. According to the American Cancer Society, there are only 15,000 new cases of soft tissue sarcoma in the United States every year.

The disease commonly affects the uterus (uterine leiomyosarcoma) but can also occur in other parts of the body including the gastrointestinal system and bladder. When it spreads, the common metastatic sites include the liver, bloodstream, and lung.

Although rare, leiomyosarcoma can be extremely aggressive and is known to be generally unresponsive to radiation or chemotherapy. Patients have the best chance of survival if the disease is found in its earliest stages (situ stage) and treated immediately.

Causes of Condition

The exact causes of leiomyosarcoma remain unknown. However, scientists speculate that genetic factors may play a contributing role in its development. Similar to other types of cancer, leiomyosarcoma can also be caused by abnormal changes in the orientation and structure of tumour suppressor genes. These genes control cell division and ensure that old cells die and are replaced at the proper time. Various studies suggest that DNA abnormalities, which could be inherited or occur spontaneously, are the reasons for cellular malignant transformation.

There are also some factors that can increase one’s risk of developing soft tissue sarcoma. It is important to note that having risk factors does not automatically mean that a patient will develop cancer. In the same way, not having risk factors does not guarantee that a patient will never develop the disease. These factors include having certain inherited disorders, such as:

  • Familial adenomatous polyposis

  • Li-Fraumeni syndrome

  • Neurofibromatosis

  • Nevoid basal cell carcinoma syndrome

  • Retinoblastoma

  • Tuberous sclerosis

  • Werner syndrome

Other risk factors include:

  • Exposure to certain chemicals such as arsenic, thorium dioxide, and vinyl chloride

  • Previous radiation therapy for another type of cancer

  • Prolonged and untreated lymphedema

  • Thyroid disorders

  • Oestrogen-related disorders

Key Symptoms

Leiomyosarcoma symptoms are hardly noticeable in the early stages. The disease starts with a small and painless lump that can be felt beneath the skin. When the tumour grows, it can compress surrounding organs or structures, resulting in the following symptoms:

  • Lumps or swollen areas of the body

  • Abdominal swelling

  • Pain

  • Abnormality in menstruation

  • Trouble breathing

Unlike other forms of cancer, leiomyosarcoma spreads to other parts of the body via the blood stream and not through the lymphatic system. Thus, leiomyosarcoma patients do not have swollen glands or lymph nodes, which tend to be the usual symptom of most cancers.

Who to See and Types of Available Treatments

Patients who experience symptoms and have risk factors mentioned above, are encouraged to see their doctors as soon as possible. This is the only way to hopefully catch the disease during the early stages when it is very responsive to treatment. Getting immediate medical treatment for leiomyosarcoma significantly improves patients’ prognosis.

The nature of leiomyosarcoma cancer makes it challenging to determine its actual source. For this reason, patients can expect the process of assessing and diagnosing the disease to be long and arduous. In many cases, patients are misdiagnosed many times and by the time they are finally referred to appropriate specialists, they have already gone through a great deal of stress.

To diagnose the condition, doctors review the patient’s medical history and conduct a thorough clinical evaluation. This is followed by a series of tests that include imaging, blood tests, and biopsies that can also help rule out other medical conditions that produce the same symptoms.

If a painful lump or mass is found, doctors will perform a fine-needle aspiration, in which a small tissue sample is collected using a thin, hollow needle. The sample is then studied closely under a microscope. Sometimes, this procedure provides inconclusive results, which creates the need for an incisional biopsy or the surgical removal of tissue samples.

Various imaging tests are also performed to gather information that will be used in planning the treatment, such as the exact location, size, and the extent of the tumour. These imaging technologies, which are also used for leiomyosarcoma staging, include:

  • Computerised tomography (CT)

  • Magnetic resonance imaging (MRI)

  • Ultrasound

Leiomyosarcoma treatment requires the coordinated efforts of different healthcare providers including medical and radiation oncologists, surgeons, and oncology nurses, among others.

Treatment methods may vary and will depend on various factors including the stage and grade of cancer, the location of the primary tumour, and the patient’s overall health condition and age.

The standard treatment for the disease is the surgical removal of the tumour along with a wide margin of healthy tissue surrounding it to ensure that no cancer cells remain in the treated site. Most commonly, the surgery is followed by radiation therapy. In cases where surgery is not an option due to the tumour’s location or the patient’s overall health condition, treatment will focus on radiation therapy. In this procedure, carefully calculated dosages of radiation are passed through the affected tissue to destroy rapidly dividing cells while taking utmost care not to damage normal cells. For patients with metastatic or locally advanced cancer, chemotherapy is also recommended and combined with surgical procedures and radiation therapy.

Leiomyosarcoma survival rate is largely dependent on how soon it was discovered and treated. The five-year survival rate for those with localised cancer is 63%. The rate goes down to just 36% for regional cancer and 14% for metastatic leiomyosarcoma.


  • Abu-Rustum, N. R.; Curtin, J. P.; Burt, M.; Jones, W. B. (1997). "Regression of uterine low-grade smooth-muscle tumors metastatic to the lung after oophorectomy". Obstetrics and gynecology. 89 (5 Pt 2): 850–852

  • Sue Ghosh; Jonathan Hecht; Tanaz Ferzandi,; Christopher Awtrey (2007). "Leiomyosarcoma of the Uterus (ULMS): A Review". The Liddy Shriver Sarcoma Initiative.

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