What is the treatment approach for synovial sarcoma?

Treatment Approach for Synovial Sarcoma

The standard treatment for synovial sarcoma involves wide surgical excision with negative margins, followed by adjuvant radiation therapy for high-grade, deep tumors >5 cm, and consideration of chemotherapy with doxorubicin plus ifosfamide for high-risk patients. 1

Diagnosis and Staging

• Diagnosis requires histopathological confirmation according to the WHO classification, complemented by molecular pathology to identify the characteristic SS18 gene rearrangement 1, 2
• Core needle biopsy is the standard procedure for diagnosis, with multiple cores taken to maximize diagnostic yield 1
• MRI is the preferred imaging modality for extremity, trunk, and pelvic soft tissue tumors, providing accurate information for diagnosis and surgical planning 1
• CT scan of the chest is mandatory for staging to exclude pulmonary metastases 1
• Regional lymph node assessment should be performed for synovial sarcoma due to higher risk of nodal involvement compared to other soft tissue sarcomas 1

Surgical Management

• Surgery is the mainstay of treatment for localized synovial sarcoma and should be performed by a surgeon specifically trained in sarcoma treatment 1, 2
• The standard surgical procedure is a wide excision with negative margins (R0), removing the tumor with a rim of normal tissue around it 1
• The surgical margin can be minimal (less than 1 cm) when resistant anatomical barriers such as muscular fasciae, periosteum, and perineurium are present 1
• Re-operation should be considered in cases of previous marginal or intralesional resection to achieve adequate margins 1

Radiation Therapy

• Radiation therapy is standard treatment following wide excision for:
  • High-grade, deep tumors >5 cm 1
  • Cases with positive or close surgical margins 2
• Radiation therapy should be administered at a dose of 50-60 Gy, with fractions of 1.8-2 Gy, possibly with boosts up to 66 Gy 1
• Radiation therapy can be delivered either postoperatively (standard) or preoperatively (typically at a dose of 50 Gy) 1
• Intraoperative radiation therapy (IORT) and brachytherapy are options in selected cases 1

Chemotherapy

• Synovial sarcomas are considered relatively chemosensitive compared to other soft tissue sarcomas 3
• For high-risk patients (high-grade, large tumors), neoadjuvant or adjuvant chemotherapy should be considered 2
• Standard chemotherapy regimens include:
  • Doxorubicin-based therapy as first-line treatment 4
  • Doxorubicin plus ifosfamide combination for fit patients with potentially better response rates 4, 3
• For metastatic disease:
  • First-line: Doxorubicin with or without ifosfamide 3
  • Second-line options: Ifosfamide (if not previously used), trabectedin, or pazopanib 4, 3

Multidisciplinary Approach

• All patients with synovial sarcoma should be managed by a specialist Sarcoma Multidisciplinary Team (MDT) 1
• Treatment decisions regarding surgery, chemotherapy, radiotherapy, and their timing should be made by the Sarcoma MDT 1
• Referral to specialized sarcoma centers is crucial for optimal outcomes 4, 5

Prognostic Factors and Follow-up

• Significant prognostic factors include tumor size >5 cm, deep-seated location, adequacy of surgical margins, and history of recurrence 5
• High-risk patients generally relapse within 2-3 years, while low-risk patients may relapse later 1, 4
• Follow-up should include:
  • Clinical examination every 3-4 months in the first 2-3 years for high-grade tumors 1
  • MRI of the primary tumor site twice yearly for the first 2-3 years, then annually 1
  • Chest imaging (X-ray or CT) every 3-4 months in the first 2-3 years, twice yearly up to 5 years, then annually 1

Common Pitfalls and Considerations

• Synovial sarcoma is often misdiagnosed due to its insidious growth, varied presentation on imaging, and associated joint pain that can be confused with trauma 2, 5
• Despite its name, synovial sarcoma does not commonly arise in an intraarticular location but usually occurs near joints 6
• Two features that may lead to an initial mistaken diagnosis of a benign process are slow growth (average time to diagnosis: 2-4 years) and small size (<5 cm at initial presentation) 6
• The cumulative dose of doxorubicin should be monitored to minimize cardiotoxic effects 4
• In older patients (>65 years) or those with comorbidities, prophylactic use of G-CSF should be considered to manage neutropenia 4