Comparison between combination therapy of percutaneous ethanol injection and radiofrequency ablation and radiofrequency ablation alone for patients with hepatocellular carcinoma

Table 1 Characteristics of patients enrolled in the present study.

	RFA alone	PEI-RFA
Total number of patient	15	60
Male/Female	10/5	45/15
Age (yr)
Mean	63	69
Range	47-74	44-86
Tumor size (cm)
Mean	2.5	3
Range	1.5-3.5	1.0- 8.0
Injected ethanol (mL)
Mean	0	7.1
Range	0-0	0-37
Child-Pugh grade
A	7	38
B	7	21
C	1	1

Table 2 Comparison of the volume of coagulated necrosis, total energy requirement and the energy requirement for inducing coagulation of per unit volume in the groups of PEI-RFA and RFA alone.

	EtOH (mL)	L (cm)	S (cm)	H (cm)	V (cm3)	T-ENE (J)	T-ENE/V (J/cm3)
RFA alone (n = 15)	0±0	2.3±0.6	2.1±0.6	2.4±0.4	6.5±3.6	38700±12549	10010±11124
PEI-RFA (n = 60)	6.9±6.6	4.2±1.2	3.5±1.0	4.0±1.1	34.0±29.3	53828±28144	2355±1690
P	<0.0001	<0.0001	<0.0001	0.0002	<0.0001	0.73	<0.0001

Sixty patients with HCC were treated with PEI-RFA by Cool-tip RF System, while 15 patients were treated with RFA alone using the same system. After the treatment, the longest and shortest diameters and the height of the coagulated necrosis were estimated by the contrast-enhanced CT scan. Each abbreviation in the table is expressing as follows: EtOH, the amount of ethanol; L, longest diameter; S, shortest diameter; H, height; V, the volume of coagulated necrosis; T-ENE, total energy requirement; T-ENE/V, the energy requirement for inducing coagulation of per unit volume. The coagulated necrosis in PEI-RFA group was enlarged in 3 dimensions compared with the group of RFA alone, although the total energy requirement was comparable between groups.

Table 3 Comparative study of coagulated necrosis in the groups classified according to the amount of ethanol injected in PEI-RFA.

	EtOH (mL)	L (cm)	S (cm)	H (cm)	V (cm3)	T-ENE (J)	T-ENE/V (J/cm3)
EtOH <6.9 mL	3.1±1.6	3.8±0.9	3.0±0.6	3.6±0.9	22.3±14.3	48 901±23219	2796±1752
(n = 41)					-1
EtOH >6.9 mL	14.9±6.1	5.1±1.3	4.3±1.2	4.8±1.1	57.6±38.2	63 931±34744	1460±1016
(n = 19)					-2.6
P	<0.0001	0.0002	<0.0001	0.0003	<0.0001	0.11	0.0014

The mean volume of ethanol injected in PEI-RFA was 6.9 mL. Therefore, 60 patients treated with PEI-RFA were divided into two groups according to the amount of ethanol injected. One group (high EtOH group) consisted of 19 cases administered with 6.9 mL and more ethanol, and the other (low EtOH group) of 41 cases less than 6.9 mLethanol. Each abbreviation in the table is expressing as follows: EtOH, the amount of ethanol; L, longest diameter; S, shortest diameter; H, height; V, the volume of coagulated necrosis; T-ENE, total energy requirement; T-ENE/V, the energy requirement for inducing coagulation of per unit volume. The volume of coagulated necrosis in the high EtOH group was 2.6 times larger than that in the low EtOH group, although the total energy requirement was comparable between groups.

Table 4 Comparative study of coagulated necrosis in the groups classified according to the total energy requirement in PEI-RFA.

	EtOH (mL)	L (cm)	S (cm)	H (cm)	V (cm3)	T-ENE (J)	T-ENE/V(J/cm3)
T-ENE <53828J	5.8±5.8	3.6±0.8	3.2±0.8	3.6±1.0	24.6±17.3	32003±12743	2038±1638
(n = 32)					-1
T-ENE >53828 J	8.1±7.3	4.8±1.2	3.8±1.2	4.4±1.2	44.0±36.4	77884±19567	2727±1687
(n = 28)					-1.8
P	0.23	0.0002	0.04	0.0028	0.014	<0.0001	0.052

All cases treated with PEI-RFA were divided into two groups. One was high energy group and the other low energy group according to the mean amount of total energy requirement (53828 Joule). Each abbreviation in the table is expressing as follows: EtOH, the amount of ethanol; L, longest diameter; S, shortest diameter; H, height; V, the volume of coagulated necrosis; T-ENE, total energy requirement; T-ENE/V, the energy requirement for inducing coagulation of per unit volume. The amount of ethanol injected was statistically comparable in both groups. The volume of coagulated necrosis in the high energy group was 1.8 times larger than that in the low energy group. The degree of the enhancing effect was smaller compared with that in cases classified by the mean amount of injected ethanol as shown in Table 3. Furthermore, the energy requirement for coagulation of per unit volume was comparable between groups.