Leiomyosarcoma (lie-o-my-o-sahr-KOH-muh), also called LMS, is a rare cancer that starts in smooth muscle. Smooth muscle acts by itself and is found in many parts of the body, including the uterus, abdomen, blood vessels, stomach and intestines. LMS is a type of soft tissue sarcoma. Treatment and outlook depend on where the cancer started, its stage and grade, and whether surgery can remove it.

LMS can start almost anywhere in the body where there is smooth muscle, including the uterus, arm, leg or abdomen, also called the retroperitoneum. Some leiomyosarcomas grow quickly and spread to other parts of the body.

Learning you have a rare cancer can bring questions and uncertainty. The outlook for leiomyosarcoma varies from person to person. Several treatment options are available. Your healthcare team can help you understand which options may be right for you.

Symptoms of leiomyosarcoma depend on where the cancer starts and how large it becomes. Some leiomyosarcomas may not cause symptoms.

Symptoms may include:

• A new or growing lump or swelling.
• Pain or pressure.
• Nausea or vomiting.
• Weight loss without trying.

Symptoms of uterine LMS may include

• Unusual vaginal bleeding.
• Pelvic pain or pressure.
• A lump in the pelvis.

Leiomyosarcoma that starts in an area of the abdomen called the retroperitoneum or in the inferior vena cava may cause belly pain, leg swelling or a mass in the abdomen. The inferior vena cava is the large vein that carries blood from the lower body back to the heart.

Leiomyosarcoma of the arm or leg can appear as a lump. The lump may or may not hurt.

When to see a doctor

Make an appointment with a healthcare professional if you notice a new or growing lump. Make an appointment if you have unexplained pain or swelling that does not go away, or vaginal bleeding that is unusual for you.

If you have been diagnosed with leiomyosarcoma, tell your care team about new or worsening symptoms.

The cause of leiomyosarcoma is not clear.

Leiomyosarcoma begins when changes happen in the DNA of a smooth muscle cell. DNA contains the instructions that tell a cell what to do. The changes tell the cell to grow and multiply when other cells would die. The extra cells can form a tumor.

Cancer cells can break away from the tumor and spread to other parts of the body. Cancer that spreads is called metastatic cancer.

Factors that may raise the risk of leiomyosarcoma include:

• Certain inherited cancer syndromes and gene changes. Examples include Li-Fraumeni syndrome, which can be caused by a change in the TP53 gene, and hereditary retinoblastoma, which can be caused by a change in the RB1 gene. These genes normally help control how cells grow and divide. Researchers are still studying inherited risk.
• Radiation therapy in the past. Rarely, LMS can develop many years after radiation therapy for another condition.

Talk with your healthcare team if you have questions about how your personal or family medical history may affect your risk.

Leiomyosarcoma can:

• Spread to other parts of the body. The lungs are a common place for LMS to spread. The liver and other areas also can be affected.
• Affect how nearby organs or blood vessels work as a tumor grows.

LMS can be a serious cancer because some tumors grow quickly or spread. But the course of the cancer varies from person to person.

Diagnosing leiomyosarcoma usually involves imaging tests and testing a sample of the tumor. Because LMS is rare, having the tissue reviewed by a pathologist with experience in sarcoma can help confirm the diagnosis. A pathologist is a doctor who examines cells and tissue to diagnose disease.

Imaging tests

Imaging tests show where a tumor is, how large it is and whether cancer may have spread. Tests may include:

• Computerized tomography (CT).
• Magnetic resonance imaging (MRI).
• Positron emission tomography (PET).

The tests you need depend on where the tumor started.

Biopsy

A biopsy is a procedure to remove a sample of tissue for testing in a lab. For many soft tissue tumors, an imaging-guided core needle biopsy can provide tissue for diagnosis.

Grades

Grade gives clues about how quickly a tumor may grow and spread. A pathologist determines the grade by examining the tumor under a microscope.

The pathologist looks at the cancer cells to see how quickly they are dividing. Higher grade tumors tend to grow and spread more quickly. The grading system may vary by tumor location.

Treatment for leiomyosarcoma depends on where the cancer started, its size, stage and grade, whether it can be completely removed with surgery, and your overall health.

LMS that has not spread to other parts of the body can sometimes be treated with the goal of cure, especially when surgery can remove all of the cancer.

Because LMS is rare, it may be helpful to get treatment at a center that regularly treats sarcoma or to consult with a center that does.

Surgery

Surgery is the main treatment for many leiomyosarcomas that have not spread to distant parts of the body. When possible, the goal is to remove all of the cancer along with a small amount of tissue around it.

The operation depends on where the cancer started.

• For uterine LMS, surgery may include removal of the uterus, called a hysterectomy.
• For LMS in the retroperitoneum, surgery may require removing the tumor along with nearby tissue or organs affected by cancer.
• For LMS of the inferior vena cava, surgery may involve removing the part of the vein that contains the tumor. Surgeons may need to repair or reconstruct the vein.

If LMS has spread to only one or a few places, surgery or another treatment directed at those tumors may be considered in some situations.

Radiation therapy

Radiation therapy uses powerful energy beams to damage cancer cells.

Radiation therapy may be used before or after surgery. It also may be used to treat a tumor that cannot be removed or to ease symptoms caused by cancer that has spread.

Whether radiation therapy is useful depends on where the LMS started and the details of the cancer.

Chemotherapy

Chemotherapy uses medicine to kill cancer cells. It is not needed for every leiomyosarcoma. Your healthcare team may talk with you about chemotherapy before or after surgery. Chemotherapy may help prevent LMS from spreading or returning after surgery. Chemotherapy also may be used when LMS cannot be removed with surgery or has spread to distant parts of the body.

Doxorubicin (Adriamycin) is one medicine commonly used for advanced LMS. Doxorubicin may be given alone or in combination with other chemotherapy.

Other options can include gemcitabine-based chemotherapy, trabectedin, dacarbazine and eribulin. The choice depends on treatments already received, where the LMS started, other health conditions and the expected benefits and side effects.

Targeted therapy

Targeted medicines act on features that help cancer cells grow. Pazopanib (Votrient) may be an option for some people with advanced LMS.

Treatment for metastatic leiomyosarcoma

LMS that has not spread to other parts of the body can sometimes be treated with the goal of cure, especially when surgery can remove all of the cancer. But once LMS has spread widely, cure is less common. Treatment may still shrink the cancer, slow its growth, ease symptoms and help people live longer.

For metastatic LMS, medicine that treats cancer throughout the body is often the main treatment. Surgery, radiation therapy or other local treatments also may be considered when there are only a few areas of spread or when a tumor is causing symptoms.

With time, you'll find things that help you cope with your cancer diagnosis. Until then, you may find that it helps to:

• Learn enough about your cancer to make decisions about your care. Ask your healthcare team about your cancer. Also ask about your test results, treatment options and, if you like, your outlook, called prognosis. Knowing more about your cancer and your treatment choices may help you make decisions about your care.
• Keep friends and family close. Keeping your close relationships strong can help you deal with your cancer. Friends and family can give you the support you need, such as helping take care of your home if you're in the hospital. They can serve as emotional support when you feel overwhelmed by cancer.
• Find someone to talk with. Find a good listener who is willing to hear you talk about your hopes and fears. This may be a friend or family member. The concern and understanding of a counselor, medical social worker, clergy member or cancer support group also may be helpful.

Ask your healthcare team about support groups in your area. In the United States, other sources of information include the National Cancer Institute and the American Cancer Society.

Start by making an appointment with a doctor or other healthcare professional if you have symptoms that worry you.

If your healthcare professional thinks that you may have leiomyosarcoma, you may be sent to a specialist. Often the specialist is a doctor who treats cancer, called an oncologist.

What you can do

Before your appointment:

• Write down your symptoms and when they started.
• Make a list of all medicines, vitamins and supplements you take.
• Gather copies of imaging reports, biopsy results and pathology reports if they were done elsewhere.
• Write down important details about your personal and family medical history.
• Bring a list of questions.
• Consider asking someone you trust to come with you to help remember the information you receive.

Questions you may want to ask include:

• Where did my leiomyosarcoma start?
• What are the stage and grade?
• Has the cancer spread? If so, where?
• Can surgery remove all of the cancer?
• What is the goal of treatment?
• What treatment choices do I have?
• Are clinical trials an option for me?

What to expect from your doctor

Your healthcare professional may ask:

• When did your symptoms start?
• Have the symptoms changed over time?
• Have you noticed a lump or swelling?
• What tests or treatments have you already had?
• Have you had any previous cancers or cancer treatments?
• What medical conditions run in your family?

Staging describes the extent of the cancer. There is not one staging system for every leiomyosarcoma because the staging system depends in part on where the cancer started.

For LMS, the stage may be based on:

• The tumor's size and location.
• Whether cancer has reached nearby lymph nodes.
• Whether cancer has spread to a distant part of the body.
• The tumor grade.

Your care team may describe LMS as stage 1, 2, 3 or 4. Ask what the stage means, whether the cancer has spread and how the stage affects treatment. Depending on the staging system, stage 4 may mean the cancer has grown into nearby organs or spread to a distant part of the body.

Cancer that has spread from where it started to another part of the body is called metastatic cancer. LMS often spreads through the blood. The lungs are a common site. The liver and other areas also can be involved.