Soft Tissue Sarcoma: Causes, Symptoms, Treatment and Prognosis — Overview, Diagnosis & Treatment Options | MyMedicPlus

Soft tissue sarcomas (STS) are a heterogeneous group of malignant tumours arising from non-epithelial, non-haematopoietic extraskeletal connective tissues, comprising more than 50 distinct histological subtypes with differing molecular characteristics, clinical behaviour, and treatment sensitivity. The most common subtypes in adults include liposarcoma (further subclassified as well-differentiated/dedifferentiated, myxoid/round cell, and pleomorphic), leiomyosarcoma, undifferentiated pleomorphic sarcoma (UPS, formerly malignant fibrous histiocytoma), synovial sarcoma, and rhabdomyosarcoma in younger patients. Approximately 13,000 new cases occur per year in the United States, with approximately 5,000 deaths. Soft tissue sarcomas occur most commonly in the extremities (approximately 50%), retroperitoneum (15-20%), trunk, and head and neck. FNCLCC (French Federation of Cancer Centres Sarcoma Group) grade — based on tumour differentiation, mitotic rate, and necrosis — is the most important prognostic factor alongside tumour size and depth. Management at specialist multidisciplinary sarcoma centres is strongly associated with improved outcomes and should be the standard of care.

The majority of soft tissue sarcomas are sporadic with no identifiable environmental cause. However, several established risk factors and hereditary predisposition syndromes are recognised. Prior therapeutic ionising radiation is a well-documented cause of radiation-induced sarcoma, typically occurring 5-20 years after radiotherapy (most commonly angiosarcoma and UPS); the risk increases with radiation dose and volume. Germline genetic syndromes predisposing to STS include Li-Fraumeni syndrome (TP53 germline mutations, high penetrance for rhabdomyosarcoma and other sarcomas), neurofibromatosis type 1 (NF1, malignant peripheral nerve sheath tumours), hereditary retinoblastoma (RB1, increased sarcoma risk), familial adenomatous polyposis/Gardner syndrome (FAP, desmoid tumours from APC mutations), and Werner syndrome. Stewart-Treves syndrome is a specific angiosarcoma arising in chronic lymphoedematous arms following axillary lymph node dissection for breast cancer. Vinyl chloride monomer exposure causes hepatic angiosarcoma. Herbicide and dioxin (Agent Orange) exposure is associated with a modestly elevated STS risk. The role of trauma is debated; most cases represent incidental discovery rather than causation.

The clinical presentation of soft tissue sarcoma is highly variable depending on anatomical location, tumour size, and histological subtype. The classic presentation is a painless or mildly painful enlarging soft tissue mass, typically deep to the investing fascia and measuring more than 5 cm in greatest dimension at diagnosis. A key clinical principle is that any soft tissue mass greater than 5 cm in size, any deep mass (below fascia), any mass increasing in size, or any mass persisting beyond 6 weeks should be evaluated with MRI and referred to a specialist sarcoma centre. Retroperitoneal sarcomas — predominantly well-differentiated/dedifferentiated liposarcoma and leiomyosarcoma — grow to enormous size asymptomatically and typically present with vague abdominal discomfort, early satiety, urinary symptoms from ureteric compression, or are detected incidentally on imaging. Extremity sarcomas may be mistaken for benign lipomas, haematomas, or muscle tears. Constitutional B symptoms (fever, night sweats, weight loss) are uncommon in low-grade tumours but may occur in high-grade and advanced disease. Rarely, STS produces paraneoplastic hypoglycaemia (insulin-like growth factor secretion).

MRI of the primary tumour site with gadolinium contrast is the imaging modality of choice, providing superior delineation of tumour extent, relationship to neurovascular structures, and compartmental anatomy that guides surgical planning and margin assessment. CT of the chest is mandatory for staging, as the lung is the predominant site of haematogenous metastasis for most STS subtypes. PET/CT may provide additional staging information in selected high-grade subtypes. Tissue diagnosis must be obtained by core needle biopsy (CNB) — not fine needle aspiration — performed at the definitive specialist sarcoma centre. Biopsy tract placement is a critical oncological principle: the tract must be planned to be excisable en bloc with the tumour during definitive surgery, without contaminating additional tissue compartments. Histological subtype classification using a combination of standard morphology, IHC, FISH for characteristic translocations (SYT-SSX/SS18-SSX1 or SS18-SSX2 in synovial sarcoma, MDM2 amplification by FISH in well-differentiated/dedifferentiated liposarcoma, FOXO1 rearrangement in alveolar rhabdomyosarcoma), and comprehensive next-generation sequencing is essential for accurate subtyping, grading, and treatment selection.

Curative-intent treatment of localised STS centres on achieving wide local excision with histologically negative (R0) margins, which is the most important determinant of local control and survival. Limb-salvage surgery is feasible in over 90% of extremity cases when performed at specialist centres, with amputation reserved for cases where adequate margins cannot be achieved with limb preservation or where vascular reconstruction is not viable. Radiation therapy — preoperative at 50 Gy (in 25 fractions) or postoperative at 60-66 Gy — reduces local recurrence rates for intermediate- and high-grade extremity STS. Adjuvant and neoadjuvant chemotherapy with doxorubicin plus ifosfamide is used selectively for high-grade, large, chemosensitive histotypes; the EORTC 62931 trial did not demonstrate survival benefit in unselected patients, but histotype-tailored approaches (STRASS2, ISG-STS 1001) improve outcomes in responsive subtypes. Metastatic STS is treated with doxorubicin first-line; trabectedin, eribulin, gemcitabine-docetaxel, and pazopanib in subsequent lines. Subtype-specific targeted therapies include tazemetostat (EZH2 inhibitor) for INI1-deficient epithelioid sarcoma, pexidartinib for tenosynovial giant cell tumour, and larotrectinib/entrectinib for NTRK-fusion-positive sarcomas.

There is no established screening programme for sporadic soft tissue sarcoma in the general population given its rarity and diverse aetiology. However, several targeted prevention and surveillance strategies are applicable. Individuals with hereditary predisposition syndromes — Li-Fraumeni (TP53), NF1, retinoblastoma (RB1), or FAP/Gardner (APC) — should be enrolled in structured surveillance programmes including whole-body MRI (Toronto protocol for TP53 carriers: annual whole-body MRI plus brain MRI) for early tumour detection. Patients with FAP should receive endoscopic surveillance and may need prophylactic colectomy and monitoring for desmoid tumours. Radiation oncologists and radiotherapy planning teams should minimise radiation field volumes and doses wherever possible to reduce radiation-induced sarcoma risk, particularly in young patients undergoing treatment for paediatric cancers. Occupational exposure to vinyl chloride and herbicides should be minimised through regulated workplace safety standards and personal protective equipment. Following breast cancer treatment, chronic lymphoedema should be aggressively managed (compression garments, lymphoedema physiotherapy) to reduce Stewart-Treves angiosarcoma risk, although absolute prevention is not achievable.

Any soft tissue lump should be evaluated promptly if it meets any of the following criteria, which collectively define the 'sarcoma red flags' endorsed by ESMO and NCCN guidelines. Seek urgent referral to a specialist sarcoma centre or experienced surgeon if: the mass is larger than 5 cm in greatest diameter; the mass is located deep to the investing fascia (i.e., cannot be freely moved relative to the underlying muscle); the mass is enlarging regardless of size; the mass is painful or tender without an apparent traumatic cause; or the mass has failed to resolve spontaneously within 6 weeks. Do not delay evaluation for a presumed 'lipoma' if any of the above features are present — malignant liposarcomas are frequently misdiagnosed as benign lipomas. Individuals with known genetic predisposition syndromes (Li-Fraumeni, NF1, FAP) should maintain their surveillance schedule and report any new masses without delay. Post-irradiation patients who develop a new or changing soft tissue mass within or adjacent to a previously irradiated field require urgent specialist evaluation for radiation-induced sarcoma.

Localised low-grade STS: 5-year OS exceeds 85%. High-grade, deep, and greater than 5 cm: 5-year OS approximately 50-60%. Metastatic disease: 5-year OS approximately 15-20%. Histological subtype profoundly impacts prognosis. Management at specialised multidisciplinary sarcoma centres consistently achieves better outcomes, including higher rates of limb salvage and R0 resection, compared to non-specialist settings. The prognosis for Soft Tissue Sarcoma: Causes, Symptoms, Treatment and Prognosis varies depending on severity at diagnosis, the patient's overall health, and how promptly treatment is initiated. With early diagnosis and appropriate management, many patients achieve good outcomes and maintain quality of life. Regular follow-up with healthcare providers is essential to monitor progress, adjust treatment as needed, and detect any complications early. Adherence to prescribed treatments and lifestyle modifications significantly improves long-term prognosis.