Session: 2B

Hypothesis: Extracorporeal high-intensity focused ultrasound (HIFU) would be used as a non-invasive local ablation for the treatment of patients with various kinds of solid tumor. Methods: A total of 1038 patients with solid tumors underwent HIFU ablation in ten Chinese hospitals. The tumors included primary and metastatic liver cancer, malignant bone tumors, breast cancer, soft tissue sarcomas, kidney cancer, pancreatic cancer, uterine myoma, benign breast tumors, hepatic hemangioma and other solid tumors. The real-time sonography-guided HIFU therapeutic system (Chongqing Haifu (HIFU) Tech Co., Ltd, China) was used in this study. The focused ultrasound was produced by 12-cm diameter therapeutic transducers with focal lengths from 90 to 150 mm, and operating frequencies of 0.8 and 1.6 MHz. The target tissue was exposed at the various acoustic focal peak intensities from 5,000 to 20,000 W cm-2. A randomized clinical trial was performed in breast cancer patients for assessing pathological changes of primary tumor treated with HIFU. Diagnostic images, including DSA, CT, MR, SPECT, and color Doppler ultrasound, were used to investigate the immediate efficacy of HIFU, and the regression of treated tumors during follow-up. By using the Kaplan-Meier method, a cumulative survival rate was calculated for long-term survival in patients with breast cancer, primary liver cancer, and osteosarcoma. Results: Pathological examination showed that the target region presented clear evidence of cellular destruction. Small blood vessels less than 2 mm in diameter were severely damaged. Furthermore, significant changes in malignant characteristics of treated cancer cell including proliferation, invasion, metastasis, and immortalisation were observed. Follow-up DSA, CT, MR and color Doppler US revealed that there was no, or reduced, blood supply in the treated-tumor, and SPECT showed that no uptake of radioisotope was observed after HIFU, both indicating a positive therapeutic response and an absence of viable tumor. Imaging at 6-12 months can showed obvious regression of the lesion. 4-year follow-up data were significantly observed in patients with HCC, osteosarcoma, and breast cancer. Among patients treated with HIFU, an extremely low major complication rate was observed.