What is Leiomyosarcoma (LMS)?

Leio means smooth,  myo means muscle, sarcoma means soft-tissue or connective-tissue cancer.


Leiomyosarcoma (LMS) is a malignancy of smooth muscles or connective tissues.  It must not be confused with leiomyoma, which is a benign tumor originating from the same tissue.

Smooth muscle cells make up the involuntary muscles, which are found in most parts of the body, including the uterus, stomach, and intestines, the walls of all blood vessels, and the skin.
It is therefore possible for leiomyosarcomas to appear at any site in the body (including the breasts); however, it is most commonly found in the uterus, stomach, small intestine, and retroperitoneum (abdominal area).

Leiomyosarcoma is a rare form of cancer;  only 1% of all cancers are sarcomas. There are both bone and soft tissue sarcomas.  Of the soft tissue sarcomas, only 13-16% are leiomyosarcomas.

Leiomyosarcomas can be unpredictable.  They can remain dormant for long periods of time and recur after many years.  They generally does not respond well to chemotherapy or radiation. It is considered “treatable” if caught early. If caught in its early stages, the most effective treatment is surgical removal. The best outcomes occur when the tumor is small, localized, and can be removed surgically with wide, clear margins.

Signs and Symptoms of Leiomyosarcoma:

Leiomyosarcoma typically does not create any noticeable symptoms in its initial stages and is usually diagnosed only after a patient develops distinct symptoms.

The Symptoms of Leiomyosarcoma

Symptoms vary depending on the location of the tumor.

You may experience some or none of these symptoms before you get a leiomyosarcoma diagnosis:

A lump or mass in the in the soft tissue of the body underneath the skin, arm, leg or abdomen.

  • growing in size
  • is greater than 5 centimeters
  • frequently painful, but not always
  • Bloating
  • Pain and unusual swelling in the stomach and body
  • Changes in  menstruation
  • Difficulty breathing

Treatments for Leiomyosarcoma Include:

Surgery – tumor resection – a surgical operation to remove the tumor, including wide margins beyond the tumor to enhance the potential for a non-recurrence.  Surgery, with as wide a margin of removal as possible, has generally been the most effective and preferred method of treatment for leiomyosarcoma.  If surgical margins are narrow or not clear of tumor, or in some situations where tumor cells were left behind, chemotherapy or radiation have been shown to give a clear survival benefit.  While LMS tends to be resistant to radiation and chemotherapy, each case is different and results can vary widely.

Radiation therapy –  Radiation therapy may be used to destroy LMS cancer cells while working to preserve the function of surrounding organs.

Chemotherapy –  chemotherapy drugs may be combined to attack and destroy leiomyosarcoma cells.  New drug therapies are considered by oncologists to combine with chemotherapy agents.

Targeted Drug Therapy –  directed at specific molecular features of LMS.  Also at one time combined with chemotherapy and /or radiation as part of the treatment plan.

Immunotherapy –  currently being investigated for application to LMS.


The National Leiomyosarcoma Foundation only offers information on research articles and does not provide medical advice to patients.

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