S2814 Efficacy and Safety of Histotripsy in Treating Hepatic Tumors: A Systematic Review and Meta-Analysis

Introduction: Histotripsy is a novel non-invasive locoregional treatment for various solid tumors involving the use of focused high-amplitude ultrasound waves to create microbubbles that rapidly expand and shrink in target tissues, resulting in cellular destruction. Initial experience in human tumors has mainly involved primary and metastatic hepatic tumors. We conducted a systematic review and meta-analysis of the efficacy and safety of histotripsy in liver tumors. Methods: We systematically searched MEDLINE, EMBASE, and Scopus from inception through May 2025 for studies evaluating histotripsy in hepatic tumors, both primary and metastatic. Primary outcomes were technical success and safety. A random-effects model was used for pooled estimates, and heterogeneity was assessed using the I² statistic. Results: Three studies involving 347 patients with 570 tumors were included – 2 prospective multicenter non-randomized trials and one retrospective cohort. Tumor types included hepatocellular carcinoma in 50 (14.4%) patients and liver metastasis from 132 (38.0%) colorectal, 48 (13.8%) neuroendocrine, 24 (6.9%) cholangiocarcinoma, 31 (8.9%) breast, 35 (10.1%) pancreatic and 27 (7.8%) other cancer sites. The number of tumors treated per procedure included 1 tumor in 215 patients, 2 tumors in 75 patients and 3 or more tumors in 57 patients. Outcome data was available for 282 patients. The mean/median age of patients ranged from 60 to 63.9, and 163 (58%) were women. The pooled technical success rate was 97.24% (95% CI, 88.74-100.0, I2 = 20.0%). The pooled rate of Grade 3 or higher adverse events was 2.40%.(95% CI, 0.18 - 7.08, I2 = 45.1%). In one study adverse events were reported in 3 patients as sepsis, pleuritic pain and hepatic failure leading to death, and in another study 3 patients who underwent histotripsy for palliative purposes experienced death from disease progression. Conclusion: Histotripsy is a non-invasive, non-thermal and non-ionizing locoregional therapy that can target multiple hepatic tumors in one procedure. Our meta-analysis demonstrates it is a safe and technically effective treatment option for both primary and secondary hepatic tumors. Further prospective studies are warranted to know its clinical durability. Additionally, studies comparing histotripsy to other locoregional therapies like chemoablation and radiofrequency ablation will help inform future directions for clinical decision making.