To evaluate the safety and efficacy of Emprint^TM microwave ablation system with Thermosphere^TM technology in the treatment of perivascular and non-perivascular liver cancer.

Clinical data of 135 liver cancer patients treated with microwave ablation system in Department of Ultrasound of the Third Affiliated Hospital of Sun Yat-sen University were retrospectively analyzed. The local ethical committee approval was received. Among them, 120 patients were male and 15 females, aged from 27 to 83 years, with a median age of 55 years. All patients underwent ultrasound-guided ablation of liver cancer using Emprint^TM microwave ablation system. All patients were divided into the perivascular (n=26) and non-perivascular groups (n=109) according to adjacent relationship between tumors and intrahepatic vessels. Propensity score matching (PSM) was used to balance the confounding factors between two groups. The evaluation indexes included technical effective rate, local tumor progression (LTP), intrahepatic distant metastasis (IDM), extrahepatic metastasis (EM) and major complications. The rates were compared by Chi-square test or Fisher's exact test.

At 1 month after ablation, imaging examination showed that all patients did not have residual lesions or recurrence, and the effective rate of ablation was 100%. Within 1 year after ablation, no LTP or EM was observed in two groups. IDM occurred in both two groups. In the perivascular group, the 1-year incidence rates of IDM before and after PSM were 7.7%(2/26) and 8.7%(2/23), and 15.6% (17/109) and 14.8%(8/54) in the non-perivascular group. No statistical significance was noted between 2 groups before and after PSM (χ²=1.084, 0.534; both P>0.05). The incidence of major complications was 3.0%(4/135), all of which occurred in the non-perivascular group, including 2 cases of bile lake formation, 1 case of postoperative gastrointestinal bleeding and 1 case of intestinal fistula. No statistical significance was observed between two groups (P=1.00). After PSM, the incidence of major complications in the non-perivascular group was 5.6%(3/54), and no statistical significance was found between two groups (P=0.55).

The novel microwave ablation system with Thermosphere^TM technology is a safe and efficacious treatment for perivascular liver cancer, which provides a new treatment option for such complicated cases.