Leiomyosarcoma (LMS) is a type of soft tissue sarcoma — and a very rare type of cancer. Doctors often find LMS cancer in the uterus. But it can occur in any of your body’s smooth muscles.

This cancer is often fast-growing, and medical professionals can help treat it when they diagnose it early. Treatments can include surgery to remove the tumor and radiation.

Read on to learn more about the symptoms, treatment, and outlook for this type of cancer.

Leiomyosarcoma (LMS) is a rare but fast-growing and aggressive type of cancer. It’s a type of soft tissue sarcoma that causes tumors to form on your body’s smooth, involuntary muscles. Your smooth muscles are in places such as your:

  • urinary system
  • connective tissues
  • eyes
  • digestive system
  • blood vessels
  • uterus

Anyone can develop LMS, but it can often be most common in people with female reproductive organs, as well as in people more than 50 years old. There are three different types of LMS:

  • Somatic soft tissue LMS. Somatic soft tissue LMS is the most common type of LMS. It grows on your body’s connective tissue and is most often in the uterus.
  • Cutaneous or subcutaneous LMS. This type of LMS grows in the muscles in your skin and eyes.
  • LMS of vascular origin. This is the rarest type of LMS. This type develops in major blood vessels.

The symptoms of LMS can vary depending on the size and location of the tumor.

Some people may not have any symptoms in the early stages of LMS. Once symptoms do occur, they often include:

When the tumor is in the stomach, additional symptoms can include:

When the tumor is in the uterus, other symptoms you may experience can include:

  • frequent urination
  • unusual vaginal discharge
  • unusual vaginal bleeding unrelated to menstruation

The cause of LMS is currently unknown. Experts believe that it doesn’t run in families. But they think there may be a genetic component that causes abnormalities in cells called oncogenes, which usually keep cells from growing unmanageably.

Researchers studied possible links between LMS and past radiation treatments, as well as exposure to chemicals like weed killers and pesticides.

Experts need to preform more research to see how strong these links are and to determine if exposure is a risk factor.

Healthcare professionals typically diagnose LMS by performing a biopsy of a mass or using imaging to evaluate unexplained symptoms.

The first step to getting an LMS diagnosis is an appointment with a medical professional. You and a doctor will discuss your symptoms and medical history.

The doctor will then perform a physical exam to determine the cause of your symptoms and order further tests like the ones below to determine the cause:

  • Imaging tests. You’ll likely have an MRI, CT scan, or angiography so that doctors can get a closer look at your tumor. The imaging tests can allow them to check the size of the tumor and see if it spread.
  • Biopsies. An imaging test can spot a tumor, but it usually won’t tell a doctor what type of cancer you have. Doctors almost always need a biopsy to confirm a diagnosis. During a biopsy, a medical professional will remove a small sample of the tumor using a hollow needle so that they can test it.

Treatment for LMS depends on the location and size of the tumor. The goal of treatment is to remove the tumor and kill any cancer cells that might have spread.

Treatment options might include:

  • Surgery. Surgery is often the first treatment for LMS. During surgery, doctors try to remove the entire tumor at once. The exact method of surgery depends on the location of the tumor.
  • Radiation therapy. Doctors can perform radiation therapy before and after surgery. If healthcare professionals perform it before the surgery, they can use this therapy to potentially shrink the tumor and make it easier to remove. After surgery, radiation therapy can help kill any leftover cancer cells.
  • Chemotherapy. Chemotherapy can help kill cancer cells that spread to other parts of your body. It can also help shrink large tumors, at times.

Medical professionals can generally treat and cure LMS when they diagnose it in the early stages. It often becomes more difficult to treat when they do not diagnose it until later stages.

Each outlook is unique to the person and depends on:

  • how far the cancer spread
  • whether doctors can remove the tumor surgically
  • how well someone responds to treatments

LMS is rare, so detailed statistics aren’t available for the overall condition. But according to the American Cancer Society, the 5-year survival rates for uterine LMS between 2011 and 2017 were:

  • 63 percent for people with tumors caught early and only located in the uterus (local)
  • 34 percent for people with tumors that spread to nearby lymph nodes (regional)
  • 13 percent for people with tumors that spread far beyond the source (distant)

Treatment for all types of cancer, including LMS, continuously improves. Likely, the current survival statistics are higher than the numbers available here at the time of publication.

An LMS diagnosis can be overwhelming and stressful. It’s important to have support during your treatment and as you recover.

And you’re not alone.

There are several great communities you can turn to — some without even leaving your home. Some LMS resources include:

  • The National Leiomyosarcoma Foundation. The National Leiomyosarcoma Foundation offers a wide variety of resources like a support hotline, in-person support group meetings, a learning library, advocacy meetings, ways to participate in clinical trials, and more.
  • The Smart Patients Sarcoma Community. The Smart Patients Sarcoma Community is an online support group for people with any type of sarcoma, including LMS, to talk, build community, and gain support.
  • The Sarcoma Alliance. The Sarcoma Alliance hosts a discussion board where you can get information, share stories, and find resources.

Leiomyosarcoma (LMS) is a rare but aggressive type of cancer that grows on the smooth muscles in the body. The cause for LMS is currently unknown, but possible links that experts research include:

  • radiation
  • exposure to certain chemicals
  • viral infections

Experts can treat LMS when they diagnose it early. That’s why it’s so important to call a healthcare professional right away if you have the following symptoms, and especially if they last for more than 2 weeks:

  • pain
  • fever
  • vomiting
  • lump under your skin
  • unintentional weight loss