What Is Leiomyosarcoma?

Medically Reviewed by Sabrina Felson, MD on March 21, 2023
5 min read

Leiomyosarcoma (LMS) is a rare cancer that 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:

  • Bladder
  • Blood vessels
  • Intestines
  • Liver
  • Pancreas
  • Skin
  • Stomach
  • Uterus

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

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
  • Weedkillers

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:

  • Bloating in your abdomen
  • Fatigue
  • Fever
  • Lump or swelling under your skin
  • Nausea and vomiting
  • Pain
  • Weight loss

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.

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.

A leiomyosarcoma diagnosis can bring up lots questions. Make a list of everything you want to know. When you see your doctor, bring someone with you who can write down the answers while you listen.

Add your own questions to this list:

  • Has my cancer spread? If so, to where?
  • What stage is it? What does that mean?
  • What are my treatment options?
  • What are the side effects of those treatments?
  • Are there any other risks?
  • Which treatment do you recommend, and why?
  • Will I need to take medication? If so, which ones?
  • Do the medications have any side effects? 
  • What are the chances the leiomyosarcoma will come back after I have this treatment?
  • How can I prepare for treatment?
  • Tell me about your experience working with people who have leiomyosarcoma.
  • Should I get a second opinion?
  • What’s my prognosis?

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.

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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.

When you have leiomyosarcoma, your days may fill up quickly with treatments, appointments, and recovery. It can affect how you feel, and how you feel about yourself.

Take good care of yourself. Everyone’s version of self-care is different, but the basics include healthy eating, being physically active, getting enough sleep, connecting with people you enjoy, and managing your stress. These are positive habits for everyone, and you need them more than ever when you’re dealing with any type of cancer. 

If your diagnosis starts to make you feel depressed or anxious, you may want to talk with a therapist who has experience in working with people who have cancer or other serious illnesses. A support group may also be a good idea. Your oncologist’s office should be able to refer you to those resources.

Self-care is also about things that bring you happiness. What made you feel your best before your diagnosis? Whether it’s a hobby or a treat, make time for that. 

Because leiomyosarcoma is an aggressive and rare cancer, survival rates are best if it’s diagnosed early and contained to one part of your body.

If you look up survival rates for leiomyosarcoma, you’re likely going to find information on soft tissue sarcomas. That’s not as specific as what you’re looking for. Plus, survival rates are about big groups of people and can’t predict what you can expect. Your best option is to ask your doctor about this.

Your doctor can figure out your prognosis based on many things specific to you. This includes your medical history, age, and current health, plus the size, grade, and type of your tumor, how deep it is, and where it started.

The National Leiomyosarcoma Foundation has patient resources about diagnosis, treatment, research, and ways to get involved. Other cancer and sarcoma foundations that cover leiomyosarcoma include:

  • The American Cancer Society
  • Genetic and Rare Diseases (GARD) Information Center
  • National Cancer Institute
  • Sarcoma Foundation of America
  • Sarcoma Alliance