What Is Leiomyosarcoma?

Sarcoma is cancer that forms in the fat, muscles, and nerves that surround and protect your organs. Leiomyosarcoma (LMS) starts in smooth muscles that line organs like your stomach, bladder, and intestines.

These muscles are involuntary -- you can't control them. For example, they make your stomach contract to digest food.

You have smooth muscles all over your body, including in your:

You can get LMS in any of these organs. But the uterus, stomach, arms and legs, and small intestine are the most common places for this cancer to start.

LMS is not the same as leiomyoma. Leiomyoma also starts in smooth muscles, but it's not cancer and doesn't spread.

Symptoms

The signs of LMS depend on the size of the cancer and where it is. Some people have no symptoms.

LMS can cause these general cancer symptoms:

LMS in your stomach or intestines can cause:

  • Stomachache
  • Black-colored stools
  • Vomiting blood

LMS in your uterus can cause:

  • Bleeding from your vagina that's not from a menstrual period
  • Discharge from your vagina
  • Need to urinate more often than usual

Call your doctor if you notice any of these symptoms.

Causes

Doctors don't know what causes LMS. It might happen because of gene changes that cause cells to grow out of control and form tumors. These changes can happen on their own, or you might have gotten the changed genes from one of your parents.

Most people who get this type of cancer are over 50. Some people get LMS years after they've had radiation for a different kind of cancer.

You also might be at risk if you've been exposed to certain chemicals, like:

  • Dioxins, which are produced when companies make things like pesticides and paper
  • Vinyl chloride, which is used to make plastic
  • Weed killers

Diagnosis

Your doctor will ask about your symptoms and medical history. You might need a biopsy to see if you have LMS. Your doctor will take a sample of tissue from the tumor with a needle or through a small cut. That sample goes to a lab where it's tested to see if it's cancer. You also might have one or more of these tests to see where exactly the tumor is and how big it's grown:

  • CT (computed tomography) scan: X-rays are taken from different angles then put together to show more information.
  • MRI (magnetic resonance imaging): Powerful magnets and radio waves are used to make detailed pictures of organs and other parts of your body.
  • Ultrasound: Sound waves are used to make images of the inside of your body.

The results will help your doctor plan your treatment.

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Treatments

Your doctor will recommend a treatment based on:

  • Where the tumor is
  • Whether it has spread
  • How fast it's spreading
  • Your age and health

Surgery is the most common treatment for LMS. Your surgeon will take out the tumor and some of the tissue around it.

Women who have cancer in their uterus will need surgery to have the organ taken out. They also may have their fallopian tubes and ovaries removed if the cancer has spread there.

Other treatments for LMS include:

  • Radiation therapy: High-energy X-rays kill cancer cells or stop their growth. This is used to shrink the tumor before or after surgery.
  • Chemotherapy: Medicine is used to kill cancer cells. Your doctor might give you chemo if your cancer has spread or comes back after treatment. You might get a combination of two or more chemotherapy drugs.

After treatment, you'll see your doctor for regular checkups. If your cancer comes back, you'll be treated again with surgery, radiation, or chemotherapy.

Scientists are looking for new ways to treat leiomyosarcoma. Clinical trials are testing new drugs to see if they're safe and if they work. These trials are a way for people to try new medicine that isn't available to everyone. Your doctor can tell you if there's a clinical trial that might be a good fit for you.

WebMD Medical Reference Reviewed by Laura J. Martin, MD on September 12, 2016

Sources

SOURCES:

Dana-Farber Cancer Institute: "Leiomyosarcoma."

Macmillan Cancer Support: "Leiomyosarcomas (LMS)."

Memorial Sloan Kettering Cancer Center: "What's New in Leiomyosarcoma."

National LeioMyoSarcoma Foundation: "Biopsy," "What is Leiomyosarcoma?"

National Organization for Rare Disorders: "Leiomyosarcoma."

Sarcoma Foundation of America: "Uterine Leiomyosarcoma."

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