Percutaneous microwave ablation vs radiofrequency ablation in the treatment of hepatocellular carcinoma

Table 1 Comparison of radiofrequency over microwave ablation methods

RFA	MWA
Electric current	Electromagnetic energy
Grounding pads (risk of burns due to ground pads)	No grounding pads (no risk of burns)
Tissue charring and boiling cause increase of impedance that reduce electrical and thermal conductivity	Rapid and homogeneous heating + ionic polarization
Lower intratumoral temperatures	Higher intratumoral temperatures
More peri-procedural pain	Less peri-procedural pain
Unpredictable ablation zone	More predictable ablation zone
Heat-sink effect	Less susceptible to heat-sink effect
Single lesion can be treated	Simultaneous treatment of multiple lesions
More procedural time	Shorter procedural time
Less ablation volume	Larger ablation volume
Similar complications and complication rate
Surgical clips or pacemaker are contraindications	Surgical clips or a pacemaker not a contraindication

RFA: Radiofrequency; MWA: Microwave ablation.

Table 2 Comparison of clinical outcomes across published series of hepatocellular carcinoma patients for microwave ablation over radiofrequency

Ref.	Method	Guidance	Patients	Lesions	Mean age	Time	Size in cm	Complete	Local recurrence (%)	Overall survival
								ablation (%)		1 yr (%)	2 yr (%)	3 yr (%)	4 yr (%)	5 yr (%)	Median (mo)
Shibata et al[50]	MWA	Percutaneous	36	46	62.5	-	< 4	89	17.4	-	-	-	-	-	-
	RFA	Percutaneous	36	48	63.6	-	< 4	96	8.3	-	-	-	-	-	-
Xu et al[84]	MWA	Percutaneous	54	112	53.4	-	2.5 ± 1.1	94.6	7.1	-	-	-	-	-	-
	RFA	Percutaneous	43	78	53.4	-	2.6 ± 1.4	89.7	12.8	-	-	-	-	-	-
Simo et al[85]	MWA	Laparoscopic, US	13	15	59	8-10 min	2.31	-	-	-	-	-	-	-	7
	RFA	Laparoscopic, US	22	27	59	10-12 min	2.53	-	-	-	-	-	-	-	19
Lu et al[78]	MWA	Percutaneous, US	49	98	50.1	5 min	3 (25/49)	94.9	11.8	81.6	61.2	50.5	36.8	-	32.5
	RFA	Percutaneous, US	53	72	54.5	10 min	3 (32/53)	93.1	20.9	71.7	47.2	37.6	24.2		27.1
Qian et al[63]	MWA	Percutaneous, US	22	22	52	-	4.8	95.5	18	-	-	-	-	-	-
	RFA	Percutaneous, US	20	20	56	-	3.5	95	15	-	-	-	-	-	-
Zhang et al[86]	MWA	Percutaneous, US	77	105	54	8 min	< 3 (36), 3.1 to 5 (41)	86.7	10.5	92.2	-	51.7	-	38.5	-
	RFA	Percutaneous, US	78	97	54	6-20 min	< 3 (47), 3.1 to 5 (31)	83.4	11.8	91	-	64.1	-	41.3	-
Abdelaziz et al[79]	MWA	Percutaneous	66	-	53.5	-	2.9 ± 0.97	96.1	3.9	96.4	62	-	-	-	-
	RFA	Percutaneous	45	-	56.8	-	2.95 ± 1.03	94.2	13.5	67.6	47.4	-	-	-	-
Ding et al[81]	MWA	Percutaneous	85	98	59	10	< 3	98.5	10.9	98.7	92.3	82.7	77.8	-	45.34
	RFA	Percutaneous	113	131	58.6	12	< 3	99	5.2	98	90.7	77.6	77.6	-	52.99
Ohmoto et al[80]	MWA	Percutaneous	49	56	64		< 2		19	89	70	49	39	-	-
	RFA	Percutaneous	34	37	67		< 2		9	100	83	70	70	-	-

MWA: Microwave ablation; RFA: Radiofrequency; US: Ultrasonography.