High-intensity focused ultrasound treatment of unresectable soft tissue sarcoma and desmoid tumours - a systematic review.

AIM: We review the evidence for high-intensity focused ultrasound (HIFU) in the treatment of soft tissue sarcoma (STS) and desmoid tumour (DT). MATERIALS AND METHODS: We searched Embase, Medline, PubMed, and Google Scholar for relevant studies between 2000-2024 using search terms 'high intensity focused ultrasound' and 'sarcoma' or 'chordoma' or 'desmoid'. We extracted data on patient demographics and treatment outcomes. RESULTS: We identified 12 studies pertaining to STS (n=178) and 15 studies pertaining to DT (n=417). These were prospective phase I/II open-label trials and retrospective case series or reports. The commonest adverse effects were skin burns, transient pain, and fever. Less common adverse effects of nerve injury and bowel perforation were depended on anatomic relations of the tumour. The majority of patients treated had unresectable disease that was partially ablated with HIFU for the purpose of local control. There was a high degree of variability in the reporting of outcomes making quantitative analysis challenging. CONCLUSION: The studied papers show that HIFU has a favourable safety profile with a potential role in patients with unresectable STS and DT. HIFU may confer advantages in cases of oligometastatic progression for disease control, complex anatomy including proximity to vital structures, recurrent cases in previously radiotherapy-exposed and/or operated locations with limited other locally-directed treatment options. However, there is limited reporting of the clinically important outcomes of recurrence and survival and further research is required, and this may represent an opportunity for later-phase trials in the UK and worldwide.