Multicenter study of local tumor control of liver tumors after histotripsy

Histotripsy is a noninvasive, nonionizing, nonthermal method of treating liver tumors, receiving FDA clearanced in October 2023. A retrospective study at four centers in the USA evaluated local tumor control (LTC) after histotripsy for primary and secondary liver tumors. The study included all patients receiving histotripsy at the four centers since FDA clearance, with at least 30 days of follow-up. LTC was assessed using contrast-enhanced imaging at postoperative days (POD) 30 and 90. Forty-seven patients received intended complete treatment to 91 liver tumors. Three complications were observed: two cases of skin irritation treated with topical ointment and one case of bacteremia. At 30 days, 95% of treated liver tumors (86 of 91) were nonviable. Two patients (one with hepatocellular carcinoma and one with hepatic adenoma) received repeat treatment between POD30 and POD90, both converted to complete response. Three patients demonstrated persistently viable disease at POD90. Thus, the calculated primary efficacy rate at POD90 was 94% and the secondary efficacy rate was 96%. Control rates were similar between primary and secondary tumors on time-to-event analysis. The authors conclude that histotripsy achieved high rates of LTC at 30 and 90 days.