Therapeutic effectiveness of high-intensity focused ultrasound (HIFU) ablation in patients with unresectable hepatocellular carcinoma.

490 Background: High-intensity focused ultrasound (HIFU) ablation is a new therapeutic method for treatment of solid tumor. To determine the efficacy and safety of HIFU, we report our experience for local therapy of primary or metastatic hepatocellular carcinoma (HCC). Methods: From January 2015 to December 2022, forty- eight patients with unresectable HCC underwent single or two therapeutic sessions of HIFU under general anesthesia. Ten patients with liver metastasis from colon cancer and three patients with liver metastasis from stomach cancer were included. We used HIFU, ultrasound-guided extracorporeal system (HIFU Technology Company, Chongqing, China). Thirty-three patients received transarterial embolization before HIFU. Thirteen patients were treated with chemotherapy before HIFU. Technical effectiveness per patient and per masses was assessed according to clinical findings and MR imaging at follow-up. Complications were also recorded. Results: We treated total 78 tumors in 48 patients. The tumor size ranged from 1.3 cm to 12 cm in diameter. Small (< 3 cm), intermediate (3-5 cm) and large tumors (>5 cm) are 44, 24 and 10 patients, respectively. Average procedure time was 4 hours 10 minutes with 68 minutes treatment time. We made the artificial pleural effusion to get treatment field in 25 patients. Mean follow-up period was 52 weeks. For the technical effectiveness per patient as follows: complete ablation with no evidence of recurrence on follow up in 18%, apparent complete ablation of target mass with progression of new lesions on follow up in 29%, recurrence after apparent complete ablation in 26%, and incomplete ablation at 2 week follow up in 27%. Average post-procedure hospital day was 5.4 days. No severe complication except mild right upper quadrant pain was observed after treatment. Conclusions: HIFU is an effective and safe treatment option for local image-guided tumor ablation in patients with unresectable HCC. Although further study is necessary, these results show that HIFU may be helpful in treating unresectable HCC.