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What is leiomyosarcoma?

Leiomyosarcoma, or LMS, is a type of rare cancer that grows in the smooth muscles. The smooth muscles are in the hollow organs of the body, including the intestines, stomach, bladder, and blood vessels. In females, there is also smooth muscle in the uterus. These smooth muscle tissues help move blood, food, and other material through the body and work without you being aware.

LMS is an aggressive cancer, which means it can grow quickly. LMS is found most often in the abdomen or in the uterus.

How common is LMS?

LMS is a type of soft tissue sarcoma and makes up between 10% to 20% of soft tissue sarcoma cases. LMS is more common in adults than children. It is estimated that only about 20 to 30 children are diagnosed with LMS in the United States per year. LMS of the uterus affects about 6 per 1 million people per year in the United States.

How is LMS diagnosed?

Symptoms depend on where the tumor is and how big it is. Some people with LMS do not have symptoms when the cancer first starts. Later, when the tumor gets larger, symptoms can include:

  • Pain
  • Unintentional weight loss
  • Nausea and vomiting
  • Lump under the skin

Imaging: If you have symptoms of LMS, your doctor will use imaging scans such as MRI, CT, angiography, and PET to look at where the tumor is and how big it is. They will also check for signs that the tumor has spread to other parts of the body.

Biopsy: To check if the tumor is LMS, your doctor will do a biopsy, taking a small sample from the tumor with a needle. An expert, called a pathologist, will study cells from the sample under the microscope to see what kind of tumor it is.

Sometimes, LMS may be mistaken for a different type of tumor or condition using imaging scans. A biopsy will confirm the tumor is LMS. Getting the correct diagnosis is very important in order to get the right treatment.

How is LMS treated?

Treatment for each patient will be unique and depends on the size and location of the tumor. You should go to an expert in LMS treatment to decide the best approach for treating your tumor. You can contact MyPART for help finding experts near you.

Surgery: The best option for LMS treatment is surgery. If all of the tumor is removed, there is a good chance of LMS being cured. If some cancer cells are left behind, there is a greater chance of the cancer coming back in the same spot, or a different part of the body.

Radiation therapy: Radiation therapy can be used around the time of surgery. The radiation is aimed at the tumor area to prevent it from growing back after it is removed.

Chemotherapy: When the LMS tumors are large, or the cancer cells have spread to other parts of the body, then chemotherapy is used in combination with surgery.

Does LMS run in families?

No. LMS without an underlying genetic condition is not known to run in families.

How does LMS form?

It is not known what causes LMS to form. Scientists are always working to understand how cancer forms, but it can be hard to prove. We do know that some genetic conditions are associated with LMS. These genetic conditions include hereditary retinoblastoma, Li-Fraumeni syndrome, neurofibromatosis type 1, tuberous sclerosis, nevoid basal cell carcinoma syndrome, Gardner syndrome, and Werner syndrome.

What is the prognosis for someone with LMS?

The estimate of how a disease will affect you in the long term is called prognosis. Every person is different, and prognosis will depend on many factors, such as:

  • Where the tumor is in your body
  • If the cancer has spread to other parts of your body
  • How much of the tumor was taken out during surgery

If you want information on your prognosis, it is important to talk to your doctor. Also, NCI has resources to help you understand cancer prognosis.

Doctors estimate LMS survival rates by how groups of people with LMS have done in the past. Because there are so few pediatric LMS patients, these rates may not be very accurate.

When LMS is identified early and is removed by surgery, prognosis is good and full recovery is likely. When LMS is already large or has spread to other parts of the body, treatment is more difficult and the prognosis is not as good.