Study of microwave ablation in patients with unresectable soft tissue sarcoma.

e23545 Background: Currently, the main treatment for soft tissue sarcoma is a combination of radiotherapy, chemotherapy and complete surgical resection. However, there is no ideal method for soft tissue sarcoma after multiple recurrences, large tumours, insensitivity to radiotherapy or failure of down grade therapy. Microwave ablation is one of the main techniques for tumour thermal therapy, but its use in soft tissue sarcoma is not yet widespread. The aim of this study was to investigate the safety and efficacy of microwave ablation in refractory soft tissue sarcoma. Methods: Fourteen eligible patients with refractory soft tissue sarcoma were treated with local anaesthesia, multi-point intra-tumour needle placement under ultrasound guidance and local radiofrequency ablation (20-40 J, 2-5 minutes). For tumours larger than 5 cm in diameter, repeat ablation can be performed after 3-4 weeks. Of the 14 patients, 8 were male and 6 were female, with a mean age of 58.91 years. There were 4 cases of myxofibrosarcoma, 3 cases of dedifferentiated liposarcoma, 2 cases of malignant nerve sheath tumour, 2 cases of clear cell sarcoma and 3 cases of other sarcomas. Tumours were located in the trunk in 7 cases, in the upper limbs in 3 cases and in the lower limbs in 4 cases. Of these, 5 patients had two operations and 9 patients had three or more operations. Four cases had received first-line therapy, five cases had received second-line therapy, and five cases had received third-line therapy or more. Postoperative pain relief and wound complications were recorded. MRI was performed regularly to assess tumour shrinkage. Results: Post-operatively, all patients experienced a significant reduction in local swelling and pain. Post-operative imaging showed partial response (PR) in 11 cases and stable disease (SD) in 3 cases. The overall response rate (ORR) was 78.57%. Progression-free survival (PFS) ranged from 2-18 months with a median of 5.82 months. Complications included tumour ulceration in 2 cases, skin burns with necrosis in 2 cases and postoperative fever in 5 cases. Conclusions: For soft tissue sarcomas that cannot be removed by surgery, where tumour growth is slow and insensitive to radio/chemotherapy, local microwave ablation can achieve tumour shrinkage and reduce patient symptoms such as local swelling and pain. It is an effective treatment option for some specific sarcoma patients.