Soft Tissue Cancer (Sarcoma) is a form of malignant tumor that arises in connective tissues — the soft tissue that supports, connects, or surrounds organs. These tissues include muscle, fat, blood vessels, nerves, tendons, and the joint lining (synovium). Sarcomas are uncommon compared with other cancers and can occur at any age: some subtypes are more frequent in children while others are seen mainly in adults. A typical presentation is a lump or mass in soft tissue that may be painless at first and slowly enlarges; sarcomas most often appear in the arms, legs, or abdomen. Definitive diagnosis requires a biopsy (a tissue sample), and treatment depends on the type and stage of the tumor — options commonly include surgery, radiation therapy, chemotherapy, or targeted therapy. If you notice a persistent or growing lump, see your doctor for evaluation.

What is Soft Tissue Cancer?

Soft tissue cancer — commonly called sarcoma — is a cancer that develops in the connective tissues of the body. These soft tissues include skeletal and smooth muscle, fat (adipose) tissue, blood vessels (endothelial cells), nerve sheath cells, tendons, and the joint lining (synovium). Because connective tissues are widespread, soft tissue sarcomas (types soft tissue cancers) can appear in many sites: most often the legs, arms, abdomen, but also the neck, pelvis, or deep under the skin.

Small sarcomas are frequently painless and may remain undetected until they grow large enough to form a visible or palpable lump. As tumors enlarge, they can press on nearby muscles, vessels, or nerves and cause pain, swelling, or loss of function. For example, a slow-growing painless mass in the thigh may be a liposarcoma (a tumor from fat cells), while a mass near a joint could be a synovial sarcoma. Because presentations vary by cell of origin and location, evaluation by a specialist is important when a persistent soft tissue lump appears.

Symptoms of Soft Tissue Cancer

Because soft tissue is found throughout the body, soft tissue sarcoma can develop in many locations. The most common early sign is a painless lump in soft tissue that slowly increases in size. Small tumors often produce no symptoms until they grow large enough to press on nearby structures — for example, a mass in the thigh may press on muscles, vessels, or nerves and eventually cause discomfort, limited motion, or numbness.

Red-flag features that should prompt medical evaluation include a lump that is growing, is larger than 5 cm (about the size of a golf ball), lies deep beneath the skin, or is painful. Note that most lumps are benign, but these features align with guideline-recommended referral criteria for possible sarcoma. In some cases, depending on the tumor location, patients may experience symptoms such as chest pain or shortness of breath (thoracic tumors), abdominal pain or gastrointestinal bleeding (abdominal or gastrointestinal stromal tumors), or unexplained weight loss and fatigue.

Common local and systemic symptoms of soft tissue tumors include:

  • A lump or swelling under the skin that may feel firm or hard
  • Pain or tenderness in the area as the tumor grows and compresses muscles, nerves, or blood vessels
  • Reduced mobility or difficulty walking if the mass involves the legs or affects nearby muscles
  • Bone pain or pathologic fractures when tumors invade or press on bone
  • Shortness of breath or coughing with lung or chest involvement
  • Abdominal pain, obstruction, or gastrointestinal bleeding for abdominal or GI tumors
  • Unintentional weight loss, fever, fatigue, and general weakness (systemic signs that may appear in advanced disease)

When to see a doctor: seek prompt evaluation if you have a persistent soft tissue lump that is increasing in size, is deeper than the skin surface, is larger than 5 cm, or is painful. Primary care clinicians will often order imaging (ultrasound, MRI, or CT depending on location) and refer patients to a sarcoma specialist or multidisciplinary sarcoma center for further assessment, biopsy, and staging.

Types of Soft Tissue Cancer

Soft tissue sarcomas comprise a diverse group of tumors that arise from different cells within the soft tissue — such as fat, muscle, blood vessels, nerves, and the synovium (joint lining). Each subtype has distinct biology, common sites, and typical treatments. Below are the main types, a short description of the cell or tissue of origin, typical age or site patterns, and a brief note on usual therapy or prognosis.

  • Liposarcoma: Originates from fat (adipose) cells and is one of the more common soft tissue sarcomas in adults, often seen in middle to older age groups. Typical locations are the deep tissues of the limbs and the retroperitoneum (abdomen). Treatment usually centers on surgery; some subtypes have variable prognosis depending on histology.
  • Synovial Sarcoma: Arises near joints and tendon sheaths (often the knee region) and most frequently affects adolescents and young adults. Local control with surgery plus radiation is common; systemic therapy is considered for high-risk or metastatic disease.
  • Leiomyosarcoma: Develops from smooth muscle cells and may arise in the uterus, gastrointestinal tract, or blood vessel walls. Management typically involves surgery; chemotherapy or radiation may be used depending on stage.
  • Rhabdomyosarcoma: Originates from skeletal muscle precursor cells and is the most common soft tissue sarcoma in children. Treatment is multimodal (surgery, chemotherapy, and often radiation) and depends on subtype and location.
  • Fibrosarcoma (and related fibroblastic tumors): Arises from fibroblasts or connective tissue-forming cells and can occur in various body sites. Surgical removal with appropriate margins is the mainstay, with additional therapies based on risk.
  • Gastrointestinal Stromal Tumor (GIST): GISTs arise from the interstitial cells of Cajal in the digestive tract and commonly present in the stomach or small intestine. Many GISTs harbor KIT or PDGFRA mutations and often respond to targeted therapy (imatinib), in addition to surgery for localized disease.
  • Angiosarcoma: A cancer of the cells that line blood vessels, angiosarcoma can appear in the skin, breast, liver, or deep tissues. It is aggressive and treatment may include surgery, radiation, and systemic therapy depending on stage.
  • Kaposi Sarcoma: A vascular tumor linked to human herpesvirus 8 (HHV‑8) that commonly affects skin and mucous membranes and can involve internal organs. Presentation and management vary with immune status; treatment options range from local therapy to systemic antiviral or oncologic treatments.
  • Nerve Sheath Tumors (e.g., malignant peripheral nerve sheath tumor): These arise from cells that cover nerves and can affect cranial nerves or peripheral nerves, causing pain or neurologic symptoms. Surgery is primary treatment; prognosis depends on size, location, and association with genetic conditions (such as NF1).
  • Radiation-Induced Sarcomas: Rare sarcomas that can develop in tissues previously exposed to therapeutic radiation; they usually arise years after the initial treatment. Management is complex and often requires a multidisciplinary sarcoma center.

A few practical notes: soft tissue sarcomas (types soft tissue cancers) account for a small proportion of all cancers, but they include many distinct histologic types; treatment and prognosis vary significantly by subtype, tumor size, and location. For example, GISTs are notable for effective targeted therapy, while rhabdomyosarcoma is treated with protocols tailored to children. When a tumor type is suspected, pathologic evaluation and molecular testing (when indicated) guide the selection of surgery, radiation, chemotherapy, or targeted agents.

How Is Soft Tissue Cancer Diagnosed?

Diagnosing soft tissue cancer begins with clinical suspicion based on history and physical exam — especially when a persistent or growing soft tissue mass is found in the arms, legs, or trunk. Primary care clinicians will assess risk factors and perform a focused exam; if red-flag features are present (growing size, depth beneath the fascia, size >5 cm, or pain), prompt referral to a sarcoma specialist or multidisciplinary sarcoma center is recommended.

Imaging helps define the tumor and guide biopsy planning: MRI is preferred for most limb and trunk soft tissue lesions because it shows soft tissue planes and relationship to muscles, nerves, and vessels; CT is useful for abdominal or chest lesions; ultrasound can evaluate superficial lumps and guide needle biopsy; PET-CT may be used for staging or to assess suspected metastases. These tests evaluate cancer spread (staging), tumor size, and involvement of nearby tissues or organs.

The definitive diagnosis requires a biopsy (a tissue sample). Core needle biopsy is commonly recommended because it yields sufficient tissue for histology and molecular testing while minimizing harm. Important best practice: biopsy should be planned and performed in coordination with the surgical team or at a sarcoma center to avoid disrupting future definitive surgery or complicating local control.

Stepwise checklist for diagnosis:

  • Primary care assessment and review of risk factors (family history, prior radiation exposure)
  • Imaging: choose MRI for limb/trunk, CT for chest/abdomen, ultrasound for superficial masses; consider PET-CT for staging
  • Biopsy (usually core needle) planned with sarcoma surgical team
  • Pathology review including histology and molecular tests to classify the tumor and guide treatment
  • Staging and multidisciplinary treatment planning

If you or someone you know has a persistent lump in the arms, legs, or any soft tissue that meets the red-flag criteria, ask your clinician about urgent referral to a sarcoma center. Early, coordinated diagnosis improves the chances of effective treatment.

How Is Soft Tissue Cancer Treated?

Early diagnosis of soft tissue cancer improves the chances of successful treatment. Treatment is individualized based on tumor type, size, location, and stage and is delivered by a multidisciplinary team (surgical oncologists, orthopedic surgeons, radiation oncologists, medical oncologists, plastic surgeons, and supportive care specialists). Below are the main treatment options and practical notes about when each is used.

Surgical Treatment

Surgery is the primary curative treatment for most localized soft tissue sarcomas. The goal is complete removal of the tumor with a rim of healthy tissue (negative margins) to reduce the risk of local recurrence. Limb-sparing resections are commonly possible even for large extremity tumors when performed in specialized centers; amputation is now uncommon but may be required when tumors involve major blood vessels or nerves and limb function cannot be preserved. Reconstruction and rehabilitation (physical therapy) are integral parts of surgical care to restore function.

Radiation Therapy

Radiation therapy is used to improve local control, either before surgery (neoadjuvant) to shrink tumors and facilitate limb-sparing procedures, or after surgery (adjuvant) when margins are close or positive. It is particularly useful for tumors in the arms and legs where surgery alone might leave a high risk of recurrence. Modern radiation techniques aim to limit dose to surrounding tissues while treating the tumor bed.

Chemotherapy

Chemotherapy is systemic therapy that can treat microscopic cancer cells throughout the body. It is commonly used for high-grade, large, or metastatic soft tissue sarcomas. Standard regimens often include doxorubicin (sometimes combined with ifosfamide) for many adult sarcomas; protocols and benefit vary by subtype. In children (for example, rhabdomyosarcoma), multiagent chemotherapy is a core part of curative treatment. Chemotherapy can cause significant side effects, so patients should discuss risks, benefits, and supportive measures with their oncology team.

Targeted Therapy and Other Systemic Options

Targeted therapies act on specific molecular drivers in cancer cells. A key example is imatinib for gastrointestinal stromal tumors (GIST) with KIT or PDGFRA mutations — a major advance in treatment. Other targeted agents and newer systemic options (including select immunotherapies) may be effective for particular subtypes or in the metastatic setting. Participation in clinical trials and sarcoma research can provide access to emerging treatments and is often encouraged, especially for rare or refractory tumors.

Treatment by Stage and Subtype (Summary)

– Localized, low-risk tumors: usually surgery with or without radiation.

– Large or high-grade tumors: combined-modality care (surgery, radiation, often systemic therapy).

– Metastatic disease: systemic therapy (chemotherapy, targeted therapy, immunotherapy where indicated) with palliative or metastasis-directed surgery/radiation when appropriate.

– Subtype-specific: synovial sarcoma and leiomyosarcoma may receive chemotherapy for high-risk disease; gastrointestinal stromal tumors (gastrointestinal stromal) often respond to imatinib; rhabdomyosarcoma in children is treated with defined pediatric protocols including chemotherapy.

Supportive Care, Follow-up, and Survivorship

Care for patients includes symptom management, rehabilitation (physical and occupational therapy), and psychosocial support. Follow-up schedules vary but commonly include regular imaging to monitor for local recurrence or metastatic spread — frequency depends on tumor type, grade, and time since treatment. Discuss long-term risks (including treatment-related effects and secondary cancers) and survivorship planning with your care team.

Key practical points: seek care at a specialist sarcoma center when possible, because outcomes (local control, limb preservation, and survival) are better with coordinated multidisciplinary management. Ask your team about clinical trials and sarcoma research opportunities, as these drive improvements in treatment over the years.