Remarkable Case of Giant Synovial Sarcoma Treated with Heavy Ion Therapy: A Clinical Showcase

Remarkable Case of Giant Synovial Sarcoma Treated with Heavy Ion Therapy: A Clinical Showcase

Medical History of Ms. LQ (34-year-old, Hebei Province)

Initial Presentation (May 2022):
• Chief complaint: Chest tightness and shortness of breath
• Imaging findings: Multiple left pleural nodules (largest: 3.2×2.1 cm) on chest CT at Tianjin Cancer Hospital
• Pathological confirmation:

• Ultrasound-guided biopsy: Synovial sarcoma
• IHC: Ki-67 40%+
• Molecular studies: SS18-SSX1 fusion positive
• NGS: TMB 1.99 muts/Mb; MSS; no actionable mutations

Treatment Course:

1.First-line (May-July 2022):

• Anlotinib (oral) for 2 months
• Complications:
  • Pleural effusion (hemorrhagic suspected)
  • Left lung atelectasis
  • No improvement after drainage/antibiotics

2.Surgical intervention (Sep 2022):

• VATS left upper lobectomy + empyema decortication + pleurodesis (PLAGH)
• Adjuvant: Tislelizumab (disease progression)

3.Clinical Trial #1 (Feb-Jun 2023):

• Sintilimab ×4 cycles
• Progressive disease:
  • CT (Jun 2023): Coalescing pleural masses (15.5×7.3 cm)

4.Clinical Trial #2 (Jun 2023):

• CAN1012 intratumoral injection (Phase I)
• Treatment failure
• PET-CT findings:
  • Left pleural mass: 12.6×10 cm
  • SUVmax 18.4

5.Heavy Ion Therapy (Wuwei Center, from Jul 2023):

• Combined with sintilimab ×2 cycles
• Treatment response:
  • Session #9: >50% reduction (10→4.1 cm)
  • Final evaluation: PR (RECIST 1.1)
• Toxicity profile:
  • Grade 1 radiation dermatitis
  • Grade 1 esophagitis
  • Transient nausea/fatigue (CTCAE v5)

​​Mediastinal window findings:​​
​​Pre-treatment:​​ The tumor occupied the entire left thoracic cavity, demonstrating significant mass effect with marked cardiac compression.
​​Post-treatment:​​ The left lung showed re-expansion, with near-complete tumor regression and restoration of normal cardiac positioning.

Lung window findings:​​
​​Pre-treatment:​​ Significant compression and atelectasis of the left lung were observed.
​​Post-treatment:​​ The left lung demonstrated complete re-expansion without evidence of pneumonitis or persistent atelectasis.

Treatment Outcomes:​​

​​Pre-treatment:​​ The massive tumor caused significant compression, displacing the heart and esophagus to the right.

​​Post-treatment:​​ Marked tumor regression was achieved with complete decompression, allowing restoration of normal cardiac and esophageal positioning. The patient's symptoms of chest tightness and dyspnea significantly improved.

​​Clinical Course:​​

This young mother had progressive disease despite multiple pharmacologic interventions since initial diagnosis in May 2022 (tumor size: 3.2×2.1 cm). The tumor demonstrated continuous growth, reaching 12.6×10 cm by August 2023. Remarkably, dramatic tumor shrinkage occurred within just one month of treatment.

​​Follow-up:​​

Ms. Liu was discharged on August 31 and has returned home. We remain hopeful for continued positive outcomes in her subsequent follow-ups.