Leiomyosarcoma

Leiomyosarcoma (LMS) is a soft tissue cancer that originates in the smooth muscles that control involuntary movements. Although smooth muscle tissues are found throughout the body, most LMS tumors occur in the abdomen or uterus. For example, the smooth muscles in the gastrointestinal tract repeatedly contract and relax during digestion. Known as peristalsis, this involuntary process moves food through the digestive system.

Leiomyosarcoma is relatively rare, with approximately 1,200 new cases diagnosed in the United States each year. However, LMS is one of the more common types of soft tissue sarcoma in adults, accounting for 10–20% of cases.

What causes leiomyosarcoma?

LMS occurs when smooth muscle cells undergo harmful changes that disrupt the normal regulatory mechanisms that control cell division and death, allowing the cells to grow uncontrollably. The precise cause of these genetic mutations is not fully understood. However, scientists have identified several risk factors for leiomyosarcoma.

What are the risk factors for leiomyosarcoma?

Risk factors for LMS include:

• Inherited cancer predisposition syndromes – Li-Fraumeni syndrome and hereditary retinoblastoma have been linked to leiomyosarcoma.
• Radiation exposure – Prior radiation treatment for another cancer can lead to the development of leiomyosarcoma in the irradiated area of the body.
• Prolonged chemical exposure – Exposure to certain chemicals, such as vinyl chloride, dioxins and weedkillers can increase the risk of leiomyosarcoma.
• Advanced age – Most LMS cases are diagnosed after age 50.

What are the signs and symptoms of leiomyosarcoma?

Early-stage LMS may not cause noticeable symptoms. As a tumor grows, it may begin to compress or push away nearby organs or connective tissues, which can cause:

• Pain or swelling around the tumor
• Gastrointestinal issues, such as abdominal pain, bloating, nausea, vomiting or blackened stools
• Pain or discomfort during sexual intercourse
• Unusual vaginal bleeding or discharge
• Unintended weight loss

How is leiomyosarcoma diagnosed?

If LMS is suspected based on the symptoms, the physician will typically perform a physical examination and order imaging scans to evaluate the location and size of the tumor. Common options include:

• Angiography – A specialized, X-ray-based procedure used for blood vessel imaging
• Computed tomography (CT) scan – Can provide detailed images of bodily organs in the abdomen and most other locations
• Magnetic resonance imaging (MRI) scan – Can help a physician visualize a tumor near the spine or in an arm or leg
• Transvaginal ultrasound – Provides images of the uterus and other reproductive organs captured by a special ultrasound transducer placed in the vagina

A biopsy is needed to confirm a diagnosis of leiomyosarcoma. Usually, tissue samples are taken during an image-guided biopsy and sent to a lab for microscopic examination by a pathologist, who can identify cancerous cells. Uterine leiomyosarcoma tends to grow inside the muscular wall of the uterus, making it difficult to obtain a useful tissue sample. Therefore, the diagnosis is usually confirmed after the tumor is removed and examined.

How is leiomyosarcoma treated?

In most cases, the primary treatment for LMS is surgical removal of the tumor. When possible, the surgeon will remove the entire leiomyosarcoma in one piece along with a slim margin of surrounding healthy tissue. Uterine LMS is best treated with a hysterectomy, which involves removing the uterus. Usually, the ovaries are kept intact unless the cancer has spread.

In addition to surgery, leiomyosarcoma treatment may include:

• Radiation therapy – May be administered before surgery to shrink the tumor and make it easier to remove or after surgery to reduce the risk of recurrence
• Chemotherapy – May be considered if the tumor is large, aggressive, recurrent or metastatic
• Hormone therapy – Can aid in the treatment of uterine leiomyosarcoma by blocking the effects of estrogen, which can promote tumor growth

Scientists and clinicians are also conducting clinical trials to evaluate the effectiveness of new and existing drugs in treating leiomyosarcoma. Many of these studies focus on high-grade leiomyosarcoma, which means the cancerous cells appear to be dividing rapidly when viewed under a microscope.

Benefit from world-class care at Moffitt Cancer Center

Leiomyosarcoma is a rare and complex cancer that requires highly specialized and individualized care. The multispecialty team in Moffitt’s renowned Sarcoma Program offers the latest diagnostic and treatment options for LMS, including a robust portfolio of clinical trials that allows our patients to be among the first to benefit from promising new therapies.

If you would like to learn more about leiomyosarcoma, you can request an appointment with a specialist in our Sarcoma Program by calling 1-888-663-3488 or submitting a new patient registration form online. We do not require referrals.