What Is a Leiomyosarcoma?
A leiomyosarcoma is a malignant (cancerous) tumor found in smooth muscle. Smooth muscles are considered involuntary, meaning they work without you directing them. They’re found in blood vessels and hollow organs such as the stomach and intestines, helping to guide food, blood, saliva, and other substances.
Most cases of muscle cancer in adults are leiomyosarcomas. These tumors typically form around middle age or later. Very rarely, this soft tissue sarcoma can also develop as a type of bone sarcoma, or bone cancer.
Leiomyosarcoma can occur across the body. They most commonly form in the uterus and abdomen. Less often, leiomyosarcoma appears near the spine, in major blood vessels, or in the arms or legs.
Some leiomyosarcomas metastasize (spread), typically to the lungs or liver. Leiomyosarcoma in the uterus can spread to other reproductive organs, as well as the pelvis, abdomen, bladder, and rectum. Leiomyosarcoma can also recur (return) even after appropriate treatment.
Leiomyosarcoma is rare, with just 1,200 new cases in the U.S. each year. Still, they’re one of the more common soft tissue sarcomas, representing 14 percent of diagnoses.
The Sarcoma Program at Penn Medicine’s Abramson Cancer Center has one of the nation’s most experienced teams when it comes to caring for leiomyosarcoma. We offer specialized surgeries, the latest drug therapies, and effective cancer monitoring after treatment.
Leiomyosarcoma Symptoms
You might not notice a leiomyosarcoma right away. These tumors can compress or push away nearby organs or connective tissues rather than invade them. You may experience symptoms as the tumor grows or spreads.
Symptoms depend on tumor size and location and may include:
- Blocked blood flow to organs
- Changes in bowel or bladder function
- Gastrointestinal (GI) complaints such as belly discomfort, bloating, internal bleeding, nausea, vomiting, or black stools
- Pain or swelling coming from the affected area
- Pain or discomfort during sex
- Unintended weight loss
- Unusual vaginal bleeding or vaginal discharge
What Causes Malignant Tumors in Smooth Muscle?
Researchers don’t know what causes a leiomyosarcoma to develop. Some factors may increase your risk of developing one of these tumors.
Some people who previously received radiation therapy later develop a leiomyosarcoma as a rare side effect of treatment.
Some people inherit genetic changes from parents that cause syndromes tied to a range of health conditions, including sarcomas and other cancers. The syndromes with possible connections to leiomyosarcoma include:
- Hereditary retinoblastoma: In addition to raising the risk for the eye cancer retinoblastoma, this syndrome increases the chances of certain soft tissue sarcomas forming. These cancers include leiomyosarcoma, fibrosarcoma, and liposarcoma.
- Li–Fraumeni syndrome (LFS): While LFS is mainly connected to rhabdomyosarcoma, it can also rarely cause leiomyosarcoma.
Diagnosing Leiomyosarcoma Cancer
To evaluate a possible leiomyosarcoma, our team starts with a discussion about symptoms and a physical exam of the affected area.
If we suspect a tumor, imaging can provide details about the size and precise location. Different scans are used for different parts of the body:
- Angiography, a specialized, X-ray-based procedure, is used for blood vessels.
- Computed tomography (CT) provides the most reliable information for the abdomen and organs in most other locations, as well as any metastatic tumors.
- Magnetic resonance imaging (MRI) shows details of tumors near the spine and in the arms and legs.
- Transvaginal ultrasound provides images of the uterus and other reproductive organs via a special instrument placed in the vagina.
Taking samples of tumor tissue during an image-guided needle biopsy can often help us confirm a diagnosis. One of our specialized sarcoma pathologists will look at the sample under a microscope and runs lab tests on it.
Leiomyosarcoma in the uterus tends to grow inside the muscular wall of the uterus, making it hard to get a useful tissue sample. These cancers are usually confirmed after we carefully remove the tumor.
Our team also stages leiomyosarcoma to make the best treatment recommendations. Learn more about sarcoma diagnosis and staging.
Leiomyosarcoma Treatment
Leiomyosarcoma treatment at Penn Medicine focuses on removing the tumor. Tumors in the arms and legs may be easier to remove than those in the spine or abdomen, which may be close to or involve nerves, blood vessels, or organs.
As with sarcoma surgery for other tumor types, the best results come from taking the leiomyosarcoma out in one piece, along with a buffer of healthy tissue. In the abdomen, the operation may require taking out organs—most frequently the colon, kidneys, spleen, or pancreas. Uterine leiomyosarcoma is best removed during a hysterectomy that removes the whole uterus. If possible, we don’t remove the ovaries unless cancer has spread.
To lower the chances that cancer returns, our team may recommend radiation therapy, usually before surgery. While some larger, more aggressive tumors may also benefit from chemotherapy, it’s usually reserved for leiomyosarcoma that has returned or spread. Hormonal therapy may help some uterine leiomyosarcomas by blocking the effects of estrogen. Our treatment team may also recommend targeted therapy aimed at some of the pathways cancer uses to grow.
Doctors and scientists are also conducting sarcoma clinical trials to look at both new and existing drugs to treat leiomyosarcoma. These trials focus on leiomyosarcomas diagnosed as higher grade, meaning their cells look more aggressive under a microscope.
Learn more about sarcoma treatment at Penn Medicine, including sophisticated surgeries to spare arms and legs, navigate near the spine, and protect nerves and blood vessels.
Make an Appointment
Please call 800-789-7366 or make an appointment.
The Penn Sarcoma Program offers same-day appointments to patients who have their imaging available. To learn more, call 215-349-8200.