The Role of High-Intensity Focused Ultrasound as a Local Consolidative Therapy in Multimodal Conversion Treatment for Colorectal Liver Metastases: A Case Series.

IntroductionThis retrospective case series evaluated the feasibility, safety, and potential clinical role of high-intensity focused ultrasound (HIFU) as local consolidative therapy (LCT) in patients with initially unresectable colorectal liver metastases (CRLM).MethodsWe retrospectively reviewed five patients with CRLM between 2019-2023 who underwent HIFU ablation in addition to systemic chemotherapy. Tumor response was assessed by contrast-enhanced MRI using modified Response Evaluation Criteria in Solid Tumors (mRECIST). Adverse events, conversion to resectability, and survival outcomes were analyzed.ResultsAll five patients underwent R0 resection after treatment incorporating systemic chemotherapy, HIFU, and surgery (median HIFU-to-surgery interval 383 days; range 17-1361 days), suggesting potential utility of HIFU both as immediate consolidation and as a long-term bridge-to-resection therapy. Only mild, self-limiting adverse events (transient liver enzyme (AST/ALT) elevation and local edema) were observed; no severe complications occurred. Median overall survival (OS) from diagnosis of liver metastases was 63.8 months, with 1-, 2-, 3-, and 5-year OS rates of 100%, 100%, 80%, and 60%, respectively. Median OS from the date of first HIFU treatment was 51.4 months (1-, 2-, 3-, and 5-year rates: 100%, 100%, 80%, and 60%).ConclusionsHIFU appears to be a safe local ablative technique and may be integrated into multimodal management of initially unresectable CRLM, and may support conversion to curative-intent resection with encouraging survival outcomes in this small series. Larger prospective studies are warranted to validate these findings and define optimal patient selection and treatment sequencing.