This page was reviewed under our medical and editorial policy by

Vijay Trisal, MD, Chief Medical Officer; Surgical Oncologist, City of Hope | Duarte

This page was updated on July 18, 2023.

Leiomyosarcoma is a rare and aggressive type of soft tissue sarcoma. Soft tissue sarcomas are cancers of connective tissuesuch as the nerves, muscles, fat and other soft tissues that surround, support and connect the structures of the body.

Leiomyosarcoma grows in the smooth muscles. These muscles are located in the body’s hollow organs, including the blood vessels, intestines, stomach, bladder and uterus. Leiomyosarcoma usually occurs in the abdomen and uterus, and it may travel through the bloodstream to spread to other parts of the body.

According to the National Cancer Institute (NCI), leiomyosarcoma accounts for approximately 10 to 20 percent of soft tissue sarcoma cases. Soft tissue sarcomas account for 1 percent of cancers diagnosed in adult patients, and leiomyosarcomas account for 7 to 11 percent of those cases, according to the National Organization for Rare Disorders.

This overview will cover the basic facts about leiomyosarcoma, including:

What is a leiomyoma vs. leiomyosarcoma?

Leiomyosarcoma and leiomyoma occur in the smooth muscles of the body. But one key distinction differentiates the two conditions: Leiomyomas are benign (non-cancerous) fibroid growths that may or may not spread to other parts of the body, and they may cause pain and other symptoms that require treatment, while leiomyosarcomas are a form of cancer that may spread much more frequently and may compromise life. 

Leiomyosarcoma symptoms

Symptoms of leiomyosarcoma vary depending on where the cancer forms in the body and how far it’s progressed. Cancer patients may experience systemic changes that affect their overall health and/or cause symptoms specific to the structures directly affected by tumor growth.

Symptoms of leiomyosarcoma may include:

  • Pain
  • Fever
  • Fatigue
  • Nausea and vomiting
  • Unintentional weight loss
  • A lump under the skin
  • Swelling near the tumor

Possible symptoms of leiomyosarcoma of the digestive system:

  • Abdominal bloating/pain
  • Loss of appetite
  • Dark stools (due to the presence of blood)
  • Vomiting of blood

Possible symptoms of uterine leiomyosarcoma:

  • Changes in bladder and bowel habits
  • Unusual vaginal discharge
  • Unusual vaginal bleeding (unrelated to a period)

It’s not uncommon for patients to have no symptoms in the early stages and only become symptomatic as the tumor begins to grow.

Who is at risk?

Medical experts haven’t determined leiomyosarcoma causes. At this time, it doesn’t appear to be a hereditary condition, but some genetic conditions have been shown to be associated with leiomyosarcoma.

Leiomyosarcoma affects both men and women, and this type of cancer is more common in adults than children. Only an estimated 20 to 30 children are diagnosed with leiomyosarcoma annually in the United States, according to the NCI.

How is leiomyosarcoma diagnosed?

The following tests are used to diagnose leiomyosarcoma and determine tumor presence, size and location:

If a mass is detected, the doctor may perform a biopsy or go directly to surgery. This procedure involves using a small needle to retrieve a sample of the affected tissue. The tissue is then examined under a microscope to diagnose the condition and determine the course of treatment.

Leiomyosarcoma treatment

Leiomyosarcoma treatment varies depending on the location and size of the tumor. Treatment may consist of:

Surgery: Surgical excision and removal of the tumor and surrounding tissue is considered the first-line form of treatment for leiomyosarcoma, when possible and appropriate.

Radiation therapy: Radiation therapy uses high doses of radiation to destroy cancer cells and shrink tumors. It may be used before, during or after surgery.

Chemotherapy: Chemotherapy involves the use of certain drugs to kill cancer cells or to stop them from growing and dividing. This treatment is often prescribed in cases where the tumor is large or when cancer has spread to other areas of the body.

Targeted therapy: These drugs, developed in a laboratory, are designed to seek out features that are unique to specific cancer cells or that influence their behaviors. The goal is to stop or slow tumor growth by interfering with or attacking the genetic features of the cells that regulate growth and division.

Leiomyosarcoma prognosis

The long-term prognosis for patients with leiomyosarcoma depends on a range of factors, including:

  • The grade of the tumor
  • Where the cancer is located
  • How far it’s progressed
  • How it responds to treatment
  • The patient’s age and health at the time of diagnosis

When localized leiomyosarcoma is detected and treated before it has the chance to spread to other parts of the body, treatment typically increases the patient’s longevity.

If the tumor is large or cancer has already spread to other parts of the body, treatment may be more challenging. It’s important that patients discuss symptoms and concerns with their cancer care team as soon as possible and avoid delays in seeking care.

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