Soft tissue sarcoma is a rare type of cancer that develops in the body’s connective tissues, including muscles, fat, blood vessels, nerves, and tendons. Though uncommon, affecting only about 2 to 4 people per 100,000, these cancers can occur anywhere in the body and present unique challenges for patients and healthcare providers alike.

How Common Is Soft Tissue Sarcoma?

Soft tissue sarcomas represent less than 1 percent of all cancers in adults, making them a relatively rare group of diseases.^[7] The incidence rate stands at approximately 2 to 4 cases per 100,000 people each year.^[7] Despite their rarity, there are more than 50 different types of soft tissue sarcoma, each behaving differently and arising from various types of connective tissue throughout the body.^[1]

Adults are more likely than children to develop soft tissue sarcomas, though certain types affect younger populations more frequently.^[2] For example, rhabdomyosarcoma—a cancer affecting muscle tissue—appears more commonly in children and teenagers than in adults.^[2] The age distribution and occurrence patterns vary depending on the specific type of sarcoma, making it important for doctors to consider patient demographics when evaluating suspicious growths.

More than half of all soft tissue sarcomas develop in the arms or legs, while others commonly appear in the abdomen, chest, or the area behind the abdominal cavity called the retroperitoneum—a space at the back of the belly.^[1][5] However, because soft tissues exist throughout the entire body, these cancers can theoretically arise almost anywhere, including the head, neck, and trunk regions.^[9]

What Causes Soft Tissue Sarcoma?

The exact causes of soft tissue sarcoma remain largely unknown to medical researchers.^[2] What scientists do know is that genetic changes, called mutations—alterations in the DNA that controls how cells grow and divide—can trigger the development of these cancers. When cells in soft tissues change in ways that make them grow abnormally and uncontrollably, they can form cancerous tumors that may invade nearby areas or spread to distant parts of the body.^[2]

Some soft tissue sarcomas are linked to inherited genetic conditions passed down through families. These conditions carry mutations that increase the likelihood of developing cancer over a person’s lifetime. However, most people who develop soft tissue sarcoma do not have any identifiable inherited syndrome, and many cases occur seemingly at random without a clear family history of the disease.^[9]

The rarity of these cancers makes them difficult to study in large populations, which has slowed progress in understanding their root causes. Because there are dozens of different subtypes, each potentially having different biological triggers, researchers face the challenge of studying many distinct diseases under one umbrella term. This complexity contributes to delays in diagnosis, as doctors may initially mistake soft tissue lumps for more common, benign conditions.^[7]

Who Is at Higher Risk?

While anyone can develop soft tissue sarcoma, certain factors increase a person’s risk of developing these cancers. Understanding these risk factors can help individuals and their doctors remain vigilant for early signs of disease, though having one or more risk factors does not guarantee that cancer will develop.^[9]

People born with certain inherited genetic conditions face elevated risks. Li-Fraumeni syndrome, caused by a mutation in the TP53 gene, significantly increases susceptibility to various cancers, including soft tissue sarcomas.^[9] Another inherited condition, neurofibromatosis type 1 (also called von Recklinghausen disease), involves mutations in the NF1 gene and raises the likelihood of developing nerve-related sarcomas.^[9] Additional hereditary syndromes that increase risk include Gardner syndrome, hereditary retinoblastoma, tuberous sclerosis, and Werner syndrome.^[9]

Previous cancer treatment presents another significant risk factor. People who received radiation therapy—a cancer treatment using high-energy rays to destroy cancer cells—for other cancers may develop soft tissue sarcomas years later in or near the area that was irradiated.^[9] This risk underscores the importance of long-term follow-up care for all cancer survivors, even after successful treatment.

Chronic swelling of the arms or legs, called lymphedema, increases sarcoma risk when it persists for extended periods.^[9] This condition occurs when the lymphatic system, which normally drains fluid from tissues, becomes blocked or damaged. People who develop lymphedema after breast cancer surgery or other treatments should be monitored regularly for any unusual changes in the affected limb.

Exposure to certain chemicals in the workplace or environment has been linked to higher sarcoma rates. These substances include thorium dioxide (once used in medical imaging), vinyl chloride (used in plastics manufacturing), and arsenic.^[9] Workers in industries using these chemicals should follow safety protocols carefully and undergo regular health screenings. Additionally, infection with HIV combined with human herpesvirus 8 has been specifically linked to Kaposi sarcoma, a particular type of soft tissue cancer.^[9]

Recognizing the Symptoms

One of the most challenging aspects of soft tissue sarcoma is that these cancers often grow slowly and silently. Many people have a sarcoma for months or even years before experiencing any symptoms that prompt them to seek medical attention.^[2] This delay in symptom development can allow tumors to grow quite large before detection, potentially complicating treatment.

The most common symptom of soft tissue sarcoma is a noticeable lump or swelling under the skin.^[1] This lump typically appears painless at first, which often leads people to dismiss it as harmless. However, as the tumor grows and begins pressing against nearby nerves, muscles, blood vessels, or organs, pain may develop.^[9] The lump may feel firm to the touch and might seem to be growing larger over time, which distinguishes it from temporary swellings caused by injuries or infections.

When soft tissue sarcomas develop in the arms or legs, they may eventually interfere with normal movement and function of the affected limb.^[1] A tumor growing near a joint might limit range of motion, while one pressing on nerves could cause tingling, numbness, or weakness. These functional changes often prompt people to finally seek medical evaluation, though ideally lumps should be checked well before they cause such problems.

Sarcomas that begin in the abdomen or retroperitoneum present particular diagnostic challenges because they can grow to substantial sizes before causing noticeable symptoms.^[9] When symptoms do appear in abdominal sarcomas, they might include progressively worsening belly pain, a feeling of fullness or bloating, nausea and vomiting, or unexplained weight loss.^[2] In some cases, people might notice blood in their stool, which may appear bright red or make the stool look black and tarry.^[2]

Tumors in the chest area might grow large enough to press on the lungs or airways, leading to difficulty breathing or persistent coughing.^[9] These respiratory symptoms can be mistaken for lung infections or other common respiratory problems, which may delay accurate diagnosis. Any breathing difficulties that persist or worsen should be evaluated promptly by a healthcare provider.

Preventing Soft Tissue Sarcoma

Because the exact causes of soft tissue sarcoma remain largely unknown, and because most cases occur without identifiable risk factors, there is no guaranteed way to prevent these cancers.^[13] Unlike some cancers that can be prevented through lifestyle changes or vaccinations, soft tissue sarcomas do not have clear prevention strategies that work for the general population.

For people with inherited genetic syndromes that increase sarcoma risk, genetic counseling can provide valuable information about their specific risks and appropriate monitoring strategies. These individuals may benefit from more frequent medical examinations and imaging studies to catch any developing tumors as early as possible. Family members of people with hereditary cancer syndromes should also consider genetic testing to determine their own risk status.^[9]

Workers in industries with exposure to chemicals linked to sarcoma should strictly follow workplace safety guidelines. This includes proper use of protective equipment, adequate ventilation in work areas, and regular health monitoring. Employers have responsibility to minimize chemical exposures and provide appropriate safety training to all workers handling potentially hazardous substances.

Cancer survivors who received radiation therapy should attend all recommended follow-up appointments and remain vigilant about any new lumps or symptoms in or near the previously treated area. While the risk of radiation-induced sarcoma exists, it typically takes many years to develop, so long-term surveillance remains important even decades after initial cancer treatment.^[9]

For the general population, the most practical approach to dealing with soft tissue sarcoma risk involves awareness and prompt medical evaluation of suspicious symptoms. Performing periodic self-examinations of accessible body areas can help people notice new lumps early. Any lump that persists longer than a few weeks, continues growing, or develops pain should trigger a visit to a healthcare provider for proper evaluation. While most lumps turn out to be benign, early detection of the rare cancerous ones significantly improves treatment success and outcomes.

How Soft Tissue Sarcoma Affects the Body

Soft tissue sarcomas disrupt normal body function through several mechanisms, depending on their location, size, and growth pattern. Understanding these effects helps explain the symptoms patients experience and why early treatment is so important.

At the cellular level, sarcomas develop when genetic mutations cause connective tissue cells to escape the normal controls that regulate cell growth and division.^[5] Healthy cells grow, divide a set number of times, and then die in an orderly process. Cancer cells, however, continue dividing uncontrollably and fail to die when they should. These abnormal cells accumulate to form tumors that grow progressively larger over time.

As a soft tissue sarcoma tumor expands, it begins displacing and compressing surrounding healthy tissues. When tumors press against nerves, they can cause pain, tingling, numbness, or loss of sensation in affected areas. Compression of blood vessels may impair circulation, potentially causing swelling, color changes, or coldness in parts of the body beyond the tumor. Large tumors in the abdomen can push against the digestive organs, causing pain, nausea, early feelings of fullness when eating, or bowel changes.

Unlike benign tumors that push tissues aside but remain contained within a defined boundary, malignant sarcomas can invade directly into adjacent structures. This invasion means cancer cells actively penetrate and destroy normal tissues around them, making surgical removal more challenging. The tumor may grow into muscles, making those muscles weak or non-functional. It may invade along nerve pathways, causing progressive neurological problems. When sarcomas invade blood vessels, they gain direct access to the circulatory system, facilitating spread to distant organs.

The ability of sarcoma cells to spread, or metastasize, represents one of the most serious aspects of these cancers. Cancer cells can break away from the original tumor and travel through the bloodstream or lymphatic system to establish new tumors in distant locations. For soft tissue sarcomas, the lungs are the most common site of metastatic spread, though cancer can also reach the liver, bones, and other organs. Once sarcoma has metastasized widely, treatment becomes significantly more challenging and outcomes typically worsen.

Soft tissue sarcomas can also affect overall health through systemic effects. Large tumors require substantial energy and nutrients to sustain their rapid growth, which can contribute to unintended weight loss and fatigue in patients. Some sarcomas produce substances that trigger inflammation throughout the body, causing fever, night sweats, and general feelings of illness. These systemic symptoms, combined with the psychological stress of dealing with cancer, can significantly impact a person’s quality of life and overall well-being.

The grading of sarcomas—an assessment of how abnormal the cancer cells appear under a microscope and how quickly they are dividing—provides important information about tumor behavior. High-grade sarcomas contain very abnormal-looking cells that divide rapidly, tend to grow quickly, and have higher likelihood of spreading to other parts of the body. Low-grade sarcomas have cells that appear more like normal tissue, grow more slowly, and generally have lower risk of metastasis, though they still require treatment to prevent local growth and eventual spread.