High-intensity focused ultrasound ablation: effective and safe therapy for solid tumors in difficult locations.

OBJECTIVE The aim of this study was to evaluate the safety and efficacy of ultrasound-guided high-intensity focused ultrasound therapeutic ablation of solid tumors in difficult locations. SUBJECTS AND METHODS A procedure was performed with a focused ultrasound tumor therapeutic system which provides real-time ultrasound guidance. All patients underwent MDCT or MRI, and some patients underwent PET/CT. From November 2007 through April 2009, 31 patients with 38 lesions of the liver and pancreas in difficult locations were treated. Six patients had hepatocellular carcinoma, 13 patients had hepatic metastasis from colorectal cancer, two had hepatic metastases of breast cancer, two had hepatic metastasis of neuroendocrine tumors, one patient had lymph node metastasis of breast cancer at the hepatic hilum, six patients had pancreatic cancer, and one patient had a neuroendocrine tumor. Difficult location was defined as tumor adjacent to a main blood vessel, the heart, the gallbladder and bile ducts, the bowel, or the stomach. RESULTS The mean diameter of tumors was 2.7 +/- 1.4 cm. PET/CT, MDCT, or both on the day after one session of high-intensity focused ultrasound treatment showed complete response in all six patients with hepatocellular carcinoma, the patient with lymph node metastasis, and 22 of 24 patients with hepatic metastasis. The symptoms of all seven patients with pancreatic caner or neuroendocrine tumors were palliated, and PET/CT or MRI showed complete response of six of seven lesions. Portal vein thrombosis occurred after high-intensity focused ultrasound ablation in one patient with pancreatic cancer. No other side effects were detected in a median follow-up period of 12 months. CONCLUSION According to our short- and long-term follow-up results, ultrasound-guided high-intensity focused ultrasound ablation can be considered a safe and feasible approach to the management of solid tumors in difficult locations.