Prospectively Comparative Study Of Percutaneously Cooled-probe Microwave, Radiofrequency Ablation And Hepatectomy For Early-stage Hepatocellular Carcinoma

Purpose:(1) To compare the ablation zone, shape, highest tissue temperatures and temperature rising rate of microwave ablation (MWA) and bipolar radiofrequency ablation (RFA) using a single internally cooled probe in ex vivo and in vivo hepatic porcine model. (2) Following the requirement of randomized controlled trial (RCT), the study investigated the short-term therapeutic effectiveness of cooled-probe MWA vs RFA on early-stage hepatocellular carcinoma (HCC) to provide initially theoretical and clinical foundation for the choice of differently minimally invasive thermal ablation techniques. (3) Using prospective cohort study to compare the short-term therapeutic effectiveness of cooled-probe MWA and RFA vs hepatectomy on early-stage HCC to provide clinical foundation for the choice of differently liver cancer treatment methods.Materials and methods:1,Experimental study:MWA(n=40) were performed with a 2450 MHz and 915 MHz needle antenna(diameter 1.9 mm) respectively at 60W,70W power settings. Bipolar RFA(n=20) were performed with a 30-mm(T30) and 40-mm(T40) active tip needle electrodes(diameter 1.85 mm) respectively at an rated power 30W and 40W. In the in vivo experiment, the 2450MHz and 915 MHz MWA both at 60W and T30 bipolar RFA at 30W were performed (n=30). A thermocouple needle was placed at the place 5mm from the applicator. All of the application time were 10 min. Long-axis diameter (Dl), short-axis diameter (Ds), ratio of Ds/Dl, the temperature data 5 mm from the needle and the time of temperature 5 mm from the needle rising to 54℃were measured.2,Clinical study:(1) From October 2008 to March 2010, according to following enrollment standard, of 80 patients with biopsy-proved HCC,41 (49 nodules) were treated percutaneously with MWA and 39 (48 nodules) with RFA by randomization. The patients with a tumor size less than 5cm in diameter, with less than 3 tumors in number, with the liver function Child-Pugh class A or B classification and no evidence of extrahepatic metastasis, vein or bile duct tumor embolus and no other anti-cancer treatment receiving were enrolled in the study. Written informed consents for participation in this study were obtained from all the patients. (2) From August 2008 to March 2010, according to above mentioned enrollment standard,80 patients (97 nodules) were treated by pcrcutaneously MWA and RFA,104 patients (114 nodules) were treated by hepatectomy. They were designated as ablation group and resection group, respectively. We compared prospectively the treatment time, post-ablation hospitalization, hospital expense, technique effectiveness rate (TER), local tumor progression (LTP), complications and short-term survival between two groups.Results:1,Experimental study:Both in ex vivo and in vivo models, Ds and Dl of 915 MHz MWA were significantly larger than both of the RFA (P＜0.05); the Ds for all the 2450 MHz MWA were significantly larger than that of T30 RFA (P＜0.05).2450 MHz MWA and T30 RFA tended to produce more elliptical-shaped ablation zone. Tissue temperatures 5 mm from the needle were considerably higher with MWA (P＜0.05), meanwhile MWA achieved significantly faster rate of temperature rising to 54℃than RFA (P<0.05). For in vivo study after 10 min of ablation, the Ds and Dl of 2450 MHz MWA,915 MHz MWA and Bipolar RFA were (2.35±0.75) cm, (2.95±0.32) cm, (1.61±0.33) cm and (3.86±0.81) cm, (5.79±1.03) cm, (3.21±0.51) cm, respectively.2,Clinical study: The follow up period was 1-19 months (mean 8.48±4.91 months). (1) Comparing between percutaneously cooled-probe MWA and RFA for HCC treatment both under ultrasound guidance, two groups showed similar ablation sessions, post-ablation hospitalization, TER, LTP, short-term cumulative survival rate and complications (P>0.05). However, MWA showed slight advantage in multiple items, especially for tumors adjacent to vessels and 3cm-5cm size tumors MWA achieved slightly strong local tumor control. RFA needed higher ablation power, longer ablation time and higher hospital expense (P<0.05). (2) Comparing between percutaneously cooled-probe thermal ablation and hepatectomy for HCC treatment, two groups showed similar TER, LTP, short-term cumulative survival rate and complications (P>0.05). However, hepatectomy showed slight advantage in TER, LTP, while ablation provided lower incidence of complications. In addition, hepatectomy needed longer post-ablation hospitalization and higher hospital expense (P<0.05).Conclusion:1,Experimental study:In ex vivo and in vivo hepatic porcine model: (1) In the same ablation time limit, single cooled-probe 2450MHz MWA and 915MHz MWA may produce larger zones than bipolar RFA. (2) Single cooled-probe 2450MHz MWA and 915MHz MWA could produce higher temperature and temperature rising rate in the ablation center than bipolar RFA. Cooling effect of blood flow had less influence on the MW ablation zone than that of RFA. MWA had higher potential for complete destruction of liver tumors than RFA. (3) According to Ds/Dl ratio,2450 MHz MWA and T30 RFA tended to produce more elliptical-shaped ablation zone.2,Clinical study:For the early-stage HCC treatment:(1) Percutaneous cooled-probe MWA and RFA achieved similar short-term effectiveness, however, MWA showed slight advantage in local tumor control for tumors adjacent to vessels and 3cm-5cm size tumors, and needed less ablation time and hospital expense, saving the medical resources. (2) Percutaneous cooled-probe thermal ablation and hepatectomy achieved similar short-term effectiveness, though hepatectomy showed better local tumor control, ablation showed the advantages of lower expense, minimally invasive and repeatability.