Leiomyosarcoma is a rare and aggressive type of cancer that originates in the smooth muscles found throughout the body. This disease, which accounts for up to one-fifth of all soft tissue sarcomas, can develop in hollow organs like the uterus, stomach, intestines, bladder, or even in blood vessels. Because symptoms often don’t appear until the disease is advanced, early detection and treatment are essential for improving the chances of recovery.

Understanding How Common Leiomyosarcoma Is

Leiomyosarcoma is considered a rare cancer. In the United States, approximately 15,000 people are diagnosed with soft tissue sarcomas every year, and leiomyosarcoma represents about 10% to 20% of these cases. This means that roughly 1 in every 100,000 people in the United States will develop this type of cancer.^[1][3]

The disease can affect anyone, regardless of age or gender. However, it is most commonly diagnosed in females, particularly those over the age of 50. While leiomyosarcoma is rare in children, when it does occur in younger populations, it typically appears in the gastrointestinal tract, which includes the stomach, intestines, and related organs.^[1][6]

The rarity of leiomyosarcoma presents unique challenges. Because there are fewer cases to study compared to more common cancers, researchers have less data to work with when developing new treatments. Additionally, the disease encompasses approximately 70 different subtypes of sarcomas, making it difficult to conduct large clinical trials that produce meaningful results. This has historically led to studies that group many different sarcoma types together, even though research now indicates that different subtypes may respond differently to various treatments.^[11]

What Causes This Type of Cancer

The exact cause of leiomyosarcoma remains largely unknown to medical researchers. What scientists do understand is that the disease can develop in two primary ways: either through inherited genetic changes passed down from parents, or through genetic mutations that occur during a person’s lifetime. These genetic alterations cause normal smooth muscle cells to grow uncontrollably, eventually forming cancerous tumors.^[1]

Leiomyosarcoma originates from smooth muscle cells or their precursor cells, known as mesenchymal cells (cells that can develop into various types of connective tissue). These smooth muscles are found in many parts of the body, including the walls of hollow organs and blood vessels. Because smooth muscles are so widespread, leiomyosarcoma can theoretically develop almost anywhere in the body, though it most commonly appears in the retroperitoneum (the area behind the intestines), the uterus, and the extremities.^[3][8]

The genetic abnormalities associated with leiomyosarcoma are complex and not fully understood. The disease is characterized by what scientists call complex karyotypes (the complete set of chromosomes in a cell), suggesting that genomic instability—meaning the genetic material within cells is prone to changes and mutations—might be a driving force behind the cancer’s development.^[4]

Risk Factors That Increase Your Chances

While the precise cause of leiomyosarcoma is unclear, researchers have identified several factors that appear to increase a person’s risk of developing this cancer. Understanding these risk factors can help individuals and healthcare providers stay vigilant for early signs of the disease.

One of the most significant risk factors is a history of radiation exposure, particularly radiation therapy received at a young age. People who have undergone radiation treatment for other cancers may have an elevated risk of developing soft tissue sarcomas, including leiomyosarcoma, later in life.^[3][8]

Certain inherited genetic conditions are also linked to an increased risk of leiomyosarcoma. These conditions include Gardner syndrome, Gorlin syndrome, hereditary retinoblastoma, Li-Fraumeni syndrome (caused by mutations in the TP53 gene), neurofibromatosis type 1, tuberous sclerosis, and Werner syndrome. People with these genetic syndromes should discuss their cancer risk with their healthcare providers and consider regular screening.^[1][3]

Additionally, there appears to be a connection between leiomyosarcoma and certain viral infections. Studies have shown a possible link between the disease and Epstein-Barr virus infection, which is also known as the virus that causes mononucleosis or “mono.” Furthermore, individuals with compromised immune systems—such as those with HIV, AIDS, or those taking immunosuppressive medications—may be more vulnerable to developing leiomyosarcoma.^[6]

Recognizing the Symptoms

One of the most challenging aspects of leiomyosarcoma is that many people don’t experience noticeable symptoms in the early stages of the disease. This is partly because soft tissue is elastic and can be easily moved aside as a tumor grows, allowing the cancer to exist for some time before being discovered. Symptoms often only become apparent as the tumor grows larger or begins to affect surrounding tissues and organs.^[1][6]

When symptoms do appear, they vary greatly depending on where the tumor is located in the body and how large it has grown. Some of the most common general symptoms include a firm, painless lump that can be felt under the skin, unexplained weight loss, persistent tiredness, fever, and nausea or vomiting. Some people may also experience pain as the tumor grows and begins to compress nearby nerves or muscles.^[1]

If the leiomyosarcoma develops in the digestive system, individuals may notice abdominal pain, abdominal bloating, loss of appetite, nausea and vomiting, or black stools caused by bleeding in the digestive tract. These symptoms can sometimes be mistaken for other, more common digestive conditions, which can delay proper diagnosis.^[1]

Uterine leiomyosarcoma, which affects the muscle tissue of the uterus, can cause abnormal uterine bleeding, vaginal discharge, and frequent urination as the tumor grows and presses on the bladder. For individuals with tumors in the extremities, symptoms might include limping or difficulty using the affected limb.^[1][6]

Because soft tissue sarcomas can develop over a long period without causing obvious symptoms, any persistent, unexplained lumps, pain, or other unusual changes in your body should be evaluated by a healthcare professional. Early detection significantly improves the chances of successful treatment.

How Leiomyosarcoma Is Prevented

Because the exact cause of leiomyosarcoma is not fully understood, there are no guaranteed ways to prevent the disease. However, understanding your risk factors and taking certain precautions may help reduce your chances of developing this cancer or catch it early when treatment is most effective.

For individuals with known genetic conditions that increase cancer risk, regular monitoring and genetic counseling are important. If you have a family history of conditions like Li-Fraumeni syndrome, hereditary retinoblastoma, or other genetic syndromes linked to leiomyosarcoma, talk to your healthcare provider about appropriate screening schedules and preventive measures.^[1]

Minimizing unnecessary radiation exposure is another important consideration. While radiation therapy is sometimes necessary for treating other cancers, the decision to use radiation should always involve careful consideration of the benefits versus the long-term risks, including the potential for developing secondary cancers like leiomyosarcoma later in life.^[3]

Maintaining overall health through a balanced diet, regular exercise, and avoiding tobacco may contribute to a stronger immune system and better overall cancer prevention, though these measures have not been specifically proven to prevent leiomyosarcoma. Some research suggests that certain foods may have anti-cancer properties, including cruciferous vegetables like broccoli and cauliflower, which contain compounds that may help reduce tumor size, though more research is needed in this area.^[17]

Regular medical checkups and being attentive to changes in your body remain the most practical approaches to early detection. If you notice any unusual lumps, persistent pain, unexplained weight loss, or other concerning symptoms, seek medical attention promptly. Early-stage leiomyosarcoma is much more treatable than advanced disease.

What Happens in Your Body

Understanding what happens in the body when leiomyosarcoma develops can help patients and their families grasp the nature of this disease. Leiomyosarcoma fundamentally disrupts the normal function of smooth muscle tissue, which plays vital roles throughout the body.

Smooth muscles are involuntary muscles, meaning they work automatically without conscious control. They’re found in the walls of hollow organs like the stomach, intestines, bladder, and uterus, as well as in blood vessels throughout the body. These muscles help organs contract and move substances through the body—for example, they help move food through the digestive tract and regulate blood flow by constricting or relaxing blood vessel walls.^[1]

When leiomyosarcoma develops, normal smooth muscle cells undergo genetic changes that cause them to multiply uncontrollably. Instead of following the body’s normal signals for growth and division, these cells continue to divide, forming a mass of abnormal tissue called a tumor. These tumors are characterized by several abnormal features when examined under a microscope, including pleomorphism (variation in the size and shape of cells), numerous abnormal cell divisions (mitotic figures), and areas of dead tissue called necrosis.^[4]

Leiomyosarcoma is particularly aggressive and grows rapidly—the cancer can actually double in size in as little as one month. This rapid growth means the tumor can quickly become large enough to cause symptoms or spread to other parts of the body. The cancer cells travel through the bloodstream, which allows them to spread to virtually any soft tissue in the body. This process of cancer spreading is called metastasis, and it significantly complicates treatment.^[1]

The tumors themselves are typically soft and hemorrhagic, meaning they contain areas of bleeding. When surgeons examine removed tumors, they often find they contain multiple areas of dead tissue and blood. The complex genetic changes in leiomyosarcoma cells make them resistant to many traditional treatments, which is why this cancer is particularly challenging to treat once it has spread beyond its original location.^[4]

As the tumor grows in its original location, it begins to compress and displace surrounding healthy tissue. This mechanical pressure on neighboring structures causes many of the symptoms people experience. For example, a tumor in the abdomen might press on the intestines, causing digestive symptoms, or a tumor in the uterus might press on the bladder, causing urinary symptoms. Eventually, if left untreated, the tumor can damage organs and interfere with their normal function, leading to serious health complications.^[1]