What Is Leiomyosarcoma?

Leiomyosarcoma is a rare type of cancer that grows in smooth muscles, which are involuntary and contract on their own. This soft tissue sarcoma most commonly affects the abdominal organs but can develop anywhere in the body, including blood vessels and the skin. Because leiomyosarcomas are unpredictable and not very responsive to chemotherapy, they are commonly treated with surgical removal.

Leiomyosarcoma Symptoms

Leiomyosarcoma is often not recognized in the early stages of the disease. In most cases, early-stage tumors are asymptomatic (without symptoms). When symptoms do occur, they vary based on the tumor's size and location, as well as whether the tumor has metastasized (spread) or not.

While pain at the tumor site is possible, it is relatively uncommon. In some parts of the body, there may be swelling and a perceptible mass, but tumors can also develop in regions where they cannot be physically touched or perceived.

Leiomyosarcoma can form anywhere where smooth muscles are, including blood vessels, the gastrointestinal tract, and the genitourinary tract. Common locations include the abdomen, retroperitoneum (the space behind the abdominal cavity), larger blood vessels (like the inferior vena cava), and most especially the uterus.

People with leiomyosarcoma may only realize that something is occurring when general signs of cancer develop, including:

• Persistent fatigue
• Unexplained weight loss
• Nausea
• Vomiting
• Night sweats
• Malaise (a general feeling on unwellness)

Other characteristic symptoms may develop depending on where the tumor is situated:

• Uterus: Tumors in the uterus can cause abnormal vaginal bleeding or discharge and a change in bowel or bladder habits.
• Gastrointestinal: Tumors of the stomach, small intestine, colon, and rectum can cause melena (black, tarry stools), hematemesis (bloody vomit), and abdominal cramps. Tumors of the esophagus can cause dysphagia (difficulty swallowing) and odynophagia (painful swallowing).
• Retroperitoneum: Tumors that develop in the space between the lining of the abdomen lining and abdominal wall can result in melena, lower extremity edema (swelling), and early satiety (a feeling of fullness after only a few bites).
• Larger blood vessels: Tumors in the larger vessels of the heart and kidneys can cause lower back pain (due to reduced blood flow to the kidney) and generalized edema (mainly the lower extremities and around the eyes).
• Liver: Tumors in the liver may manifest with upper-right abdominal pain and jaundice (yellowing of the skin and/or eyes).
• Pancreas: Pancreatic tumors are more likely to cause abdominal pain than other types and may also cause melena and jaundice.

A 2014 review of studies in the journal Sarcoma concluded that no less than 81% of people with leiomyosarcoma experience distant metastases, while around half experience recurrence (return of the cancer) even with aggressive treatment.

Causes

As with any form of cancer, the cause of leiomyosarcoma is poorly understood. Generally speaking, all cancers are the result of abnormal changes in the structure and activity of oncogenes and/or tumor suppressor genes. In the simplest terms, oncogenes can cause cancer when they are "turned on," while tumor suppressor genes can cause cancer when they are "turned off."

These changes are believed to stem from genetic and environmental factors. A number of specific genetic mutations involving the TP53, ATRX, and MED12 genes have been implicated in certain forms of leiomyosarcoma, although having these doesn't mean you develop the disease.

It has been hypothesized that certain environmental factors can cause spontaneous changes to oncogene or tumor suppressor genes in people genetically predisposed to leiomyosarcoma. High-dose radiation used to treat other cancers is commonly cited as a cause, particularly in children, while certain chemical herbicides, arsenic, and dioxin have also been implicated (albeit weakly).

Leiomyosarcomas are rare, affecting around two of every 100,000 people, but are among the most common sarcomas found in adults. This disease affects men and women equally and occurs more often in adults than in children. For reasons unknown, uterine leiomyosarcoma affects black women at twice the rate of white women.

Diagnosis

A diagnosis of leiomyosarcoma is usually made with a variety of tests and evaluations, including a review of symptoms and medical history, a physical exam, blood tests, imaging studies, and a biopsy of the tumor itself.

Note: Your healthcare provider may also refer to leiomyosarcoma based on where the tumor is located. For example, most leiomyosarcomas of the gastrointestinal tract fall under the classification of gastrointestinal stromal tumors (GIST).

Blood Tests

Blood tests are not used to identify leiomyosarcoma but rather to detect signs that are characteristic of the disease, which may support a diagnosis.

These may include a complete blood count (CBC) to identify irregularities in your blood composition or structure, as well as a comprehensive metabolic panel that measures levels of chemicals from the liver, bones, and other organs that tend to increase or decrease in the presence of cancer.

Imaging Studies

Imaging studies used in the diagnosis and evaluation of leiomyosarcoma include:

• X-ray, which uses ionizing radiation to create detailed images (typically used when a tumor is can be felt on examination)
• Computed tomography (CT), which uses a series of X-ray image to create three-dimensional "slices" of your internal organs
• Magnetic resonance imaging (MRI), which uses powerful radio waves and magnetic fields to create highly detailed images, especially of soft tissues
• Positron emission tomography (PET), which uses a radioactive tracer to locate areas of increased metabolic activity, such as those that occur with the development of malignant tumors

Though imaging studies are able to locate tumors, especially those that are not readily felt, they cannot distinguish between leiomyosarcoma and its benign counterpart, leiomyoma. (A uterine fibroid is one example of a leiomyoma.)

Imaging studies can also provide information on the precise size, location, and extent of a tumor in advance of surgical removal.

Biopsy

To make a definitive diagnosis, a sample of the tumor must be obtained and sent to a pathologist for evaluation under the microscope.

One way that is this done is with fine-needle aspiration (FNA) in which a hollow needle is inserted into the tumor through the skin to extract cells. An ultrasound or live MRI scan may be used to guide the correct placement of the needle.

If FNA is unable to provide conclusive evidence of cancer, a thicker core-needle biopsy or incisional biopsy (in which a portion of the tumor is removed) may be used. Excisional biopsy, a more invasive surgical procedure used to remove an entire tumor, is generally avoided if sarcoma is suspected. Instead, a well-planned resection surgery is preferred after the disease has been diagnosed.

A biopsy is not only essential in diagnosing leiomyosarcoma—it also provides a starting point for the staging of the disease.

Staging and Grading

After the diagnosis of leiomyosarcoma has been confirmed, the tumor will be staged to determine how far cancer has advanced. The determination helps direct the appropriate treatment.

Staging is based on the size of the tumor, whether the tumor has spread to nearby lymph nodes, and whether there is spread to distant organs.

The tumor will also be graded based on its appearance of the tumor cells under the microscope. Grading factors include how quickly the tumor cells divide and how much of the tumor is made up of necrotic (dead) tissue.

Treatment

The treatment of leiomyosarcoma will often involve a variety of cancer specialists, including a surgical oncologist, a radiation oncologist, and a medical oncologist (who oversees chemotherapy). It is not uncommon to have two to three specialists working in coordination at any one time.

Initial treatment with surgery is typical, but chemotherapy and radiation therapy are often used to help support this and treat tumors that have returned or metastasized to other parts of the body.

Surgery

Because leiomyosarcoma is so variable and often aggressive, surgical resection of the tumor is generally considered the first line—and the gold standard—of treatment. This is a procedure in which the tumor and surrounding tissue (margins) are surgically removed.

Evaluations are performed beforehand to determine if the margins are positive (meaning populated with cancer cells) or negative (meaning cancer-free). This will determine how much tissue needs to be resected.

Depending on the size and location of the tumor, open surgery (involving an incision and traditional surgical tools) or minimally invasive laparoscopic ("keyhole") may be performed. Some surgical units can even perform robotic surgery to ensure more precise resection, particularly in areas where there are vulnerable nerves or blood vessels.

Reconstructive surgery may also be performed, either during the resection or at a later date, if the resection causes noticeable deformation. This may involve the construction of a myocutaneous flap in which skin, subcutaneous tissue, fat, and muscles are harvested from another part of the body to "fill in" visible depressions in another.

Radiation

In addition to surgical resection, a leiomyosarcoma treatment plan often involves postoperative radiation to destroy all remaining cancers cells around the tumor site. Radiation works by damaging the genetic material of cancer cells, thereby preventing them from replicating and spreading. Radiation is also sometimes delivered intraoperatively while the wound is still open.

To reduce the risk of side effects, the radiation dose is carefully calculated. Depending on the location and size of the tumor, procedures like external beam radiotherapy (EBRT) or stereotactic body radiotherapy (SBRT) may be used to direct a precise beam of radiation at the targeted site.

In some cases, radiation may be used prior to surgery to reduce the size of a tumor. Referred to as neoadjuvant radiation therapy, this may involve beam radiation or an alternative known as brachytherapy in which radioactive "seeds" are implanted into the tumor itself.

If a tumor is inoperable or there is metastatic or recurrent disease, radiation may be used to impede the growth of the tumor or to reduce pain as part of palliative care. Some specialists recommend the use of proton beam therapy in such instances, which utilizes positively charged protons rather than ionizing radiation.

Chemotherapy

Where chemotherapy is often the first-line treatment for certain cancers, it is more commonly used to support surgery and radiation therapy in people with leiomyosarcoma.

Chemotherapy is used to kill cancer cells that extend beyond the primary leiomyosarcoma tumor. Traditional chemotherapeutic drugs work by targeting fast-replicating cells like cancer for neutralization. While effective, the drugs harm other fast-replicating cells like hair and mucosal tissues, leading to side effects.

Newer drugs have been developed in recent years that may offer hope to people with leiomyosarcoma. Among them are Yondelis (trabectedin), a chemotherapeutic drug that can slow the speed of cancer recurrence (although it has not been shown to extend survival).

Experimental approaches are also being explored, including some that may one day directly target cancer stem cells. Other scientists are exploring immunotherapies that provoke a cancer-fighting immune response or angiogenesis inhibitors that prevent the formation of new blood vessels that deliver blood to tumors.

Prognosis

The prognosis (predicted outcome) for people with leiomyosarcoma can vary by the stage and grade of cancer. Not surprisingly, the more advanced the cancer stage, the less favorable the outcomes.

One of the prognostic factors influencing survival times is the ability to resect a tumor. Doing so will invariably increase survival times, sometimes significantly.

A 2018 review from Harvard Medical School reported that women treated surgically for uterine leiomyosarcoma—the most common form of the disease—had five-year survival rates of 76% for stage 1, 60% for stage 2, 45% for stage 3, and 29% for stage 4.

A Word From Verywell

Leiomyosarcoma is a rare type of cancer that can be very serious if not diagnosed and treated quickly. However, with proper treatment, there is a chance of living disease-free for a significant period of time—even with recurrent or advanced disease.

If faced with a leiomyosarcoma diagnosis, it is important to build a support network of health professionals, family, friends, and others to see you through treatment and discovery. If in need of support from cancer survivors, connect with the Leiomyosarcoma National Foundation's Facebook page or the Leiomyosarcoma Support & Direct Research Foundation's moderated Facebook group.