Leiomyosarcoma is a rare type of soft tissue cancer. This cancer starts in cells that make up smooth muscle which can be found throughout the body. These muscles control involuntary movement of organs, blood vessels, and skin.

Leiomyosarcoma can develop in any smooth muscle, but is most common in the muscle of the uterus, abdomen, and pelvis.

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Cancer occurs when cells in the body divide without control or order. Eventually these uncontrolled cells form a growth or tumor. These growths are malignant which means they can invade nearby tissues including the lymph nodes. Cancer that has invaded the lymph nodes can then spread to other parts of the body.

Cancer growth occurs when there are problems in the DNA of cells. It is not clear exactly what causes these problems, but is probably a combination of genetics and environmental factors.

Risk Factors

Some genetic disorders are associated with an increased risk of leiomyosarcoma. Examples include:

  • Retinoblastoma —a rare type of cancer that affects the retina of the eye
  • Familial adenomatous polyposis—abnormal growth of adenomatous polyps in the colon and/or rectum that can transform into cancer
  • Neurofibromatosis type 1
  • Li-Fraumeni syndrome
  • Werner syndrome
  • Nevoid basal cell carcinoma syndrome (Gorlin syndrome)

Other factors that may increase the chance of leiomyosarcoma include:

  • Past history of cancer treatment with radiation therapy or tamoxifen
  • Exposure to certain chemicals used to make plastics or weed killers


Leiomyosarcoma usually does not have symptoms. If present, symptoms will vary depending on the tumor’s location, size, and growth. As the tumor grows, it presses on nearby structures, causing problems. When they appear, general symptoms may include:

  • Swelling or a lump
  • Abdominal bloating
  • Abnormal vaginal bleeding
  • Shortness of breath
  • Pain
  • Numbness or muscle weakness


You will be asked about your symptoms and medical history. A physical exam will be done. This includes a thorough examination of the affected area and blood tests.

Imaging tests can help diagnose and determine the extent of cancer. Tests may include:

A biopsy will help tell the difference between a noncancerous or cancerous growth. A tissue sample from the affected area is examined under microscope for the presence of cancer cells.

The physical exam, combined with all of the test results, will help to determine the type, grade, and stage of cancer. Staging is used to guide a treatment plan. Leiomyosarcoma is staged from I-IV (1-4). Stage I is a cancer that has stayed in one area, while stage IV indicates a spread to other parts of the body. Cancer cells may also be graded by how fast they might grow and spread.


Cancer treatment varies depending on the location, size, grade, and stage of the tumor, your age, and overall health. Since leiomyosarcoma is rare, treatment with a specialty team may be needed. A combination of treatments may be best.


In most cases, leiomyosarcoma is treated with surgery. If the tumor is only affecting local tissue, it may be the only treatment that is needed. The cancerous tissue and a surrounding border of healthy tissue will be removed. Any affected lymph nodes near the tumor may also be removed. The exact type and extent of the surgery will depend on the location of the cancer.

Radiation Therapy

Radiation therapy is the use of radiation to kill cancer cells and shrink tumors. Radiation therapy may be:

  • External —radiation directed at the tumor from a source outside the body
  • Internal (brachytherapy)—radioactive materials placed into the body near the cancer cells

Radiation therapy may be used to shrink cancer before surgery, to kill off any potential remaining cancer cells after surgery, or to reduce the size of tumors if surgery cannot be done.


Chemotherapy is the use of drugs to kill cancer cells. Chemotherapy may be given in by IV, injection, or mouth. The drugs enter the bloodstream and travel through the body killing mostly cancer cells, but also some healthy cells.

Chemotherapy may be used for leiomyosarcoma that has spread to other places in the body.


There are no current guidelines to prevent leiomyosarcoma because the cause is not clear.


American Cancer Society

Sarcoma Alliance


Canadian Breast Cancer Foundation

Sarcoma Cancer Foundation of Canada


Leiomyosarcoma. The Liddy Shriver Sarcoma Initiative website. Available at: Accessed January 5, 2018.

Leiomyosarcomas (LMS). MacMillian Cancer Support website. Available at: Updated March 31, 2016. Accessed January 5, 2018.

Sarcoma and bone cancer types. Dana-Farber Cancer Institute website. Available at: Accessed January 5, 2018.

Uterine leiomyosarcoma. EBSCO DynaMed Plus website. Available at: Updated June 22, 2016. Accessed January 5, 2018.

Last reviewed November 2018 by EBSCO Medical Review Board Mohei Abouzied, MD, FACP  Last Last updated: 11/18/2016