Comparison of ultrasonography-guided percutaneous microwave ablation for subcapsular and nonsubcapsular hepatocellular carcinoma ☆

Abstract Purpose To compare the prognosis of subcapsular and nonsubcapsular hepatocellular carcinoma (HCC) after ultrasonography (US)-guided percutaneous microwave ablation (MWA). Materials and methods From January 2012 to December 2015, 463 enrollment patients (382 men, 81 women; age range, 24–95 years) with a single HCC underwent US-guided percutaneous MWA. The patients were divided into two groups according to tumor location: subcapsular (n = 224) and nonsubcapsular (n = 239). Therapeutic efficacy was assessed by contrast enhanced imaging after MWA. The technique effectiveness rate, the local tumor progression (LTP) rate, overall survival (OS) rate and complication were compared between two groups. Results There were no significant differences in the mean treatment sessions ( p =  0.105) and the mean number of antenna insertions (p = 0.065) between two groups. No significant difference in the technique effectiveness rate was found between subcapsular and nonsubcapsular tumors (95.5% vs 98.3%, p  = 0.089). The respective 1-, 2-, 3-, and 4-year cumulative LTP rates were 5.0%, 5.5%, 5.5% and 5.5% in subcapsular group and 6.4%, 6.4%, 6.4% and 6.4% in nonsubcapsular group, respectively(p = 0.861). The 1-, 2-, 3-, and 4-year OS rates were estimated to be 95.7%, 90.1%, 82.9%, and 71.1% in subcapsular group and 98.5%, 92.8%, 83.2%, and 73.6% in nonsubcapsular group, respectively (p = 0.426). There was no significant difference in major complication rates between the subcapsular group (2.2%) and nonsubcapsular group (1.3%) (p = 0.653). There was higher postoperative pain rate in subcapsular group (13.4%) than nonsubcapsular group (7.1%) (p = 0.025). Conclusions There were no significant differences in the technique effectiveness rate, cumulative LTP rate, OS rate and major complication rate between subcapsular and nonsubcapsular group after MWA for HCC.