Prognosis of microwave ablation for hepatocellular carcinoma: does age make a difference?

Figures & data

Table 1. Comparison of included and excluded characteristics.

	Included	Excluded	p Value
N	883	229	–
Age (years)	58 (51–65)	58 (51–66)	0.997
Sex (male)	716 (81.1%)	190 (83.0%)	0.514
Nodule size (cm)	2.5 (1.9–3.4)	2.5 (1.8–3.3)	0.640
Number of nodules	2 (1–3)	2 (1–3)	0.584
Charlson comorbidity index	2 (1–3)	2 (1–4)	0.413
HBV infection	720 (81.5%)	189 (82.5%)	0.729
HCV infection	101 (11.4%)	26 (11.4%)	0.971
Alcoholic	8 (0.9%)	1 (0.4%)	0.695
Child Pugh grade			0.874
A	850 (96.3%)	222 (96.9%)
B	32 (3.6%)	7 (3.1%)
C	1 (0.1%)	0 (0.0%)
Extrahepatic metastasis	26 (2.9%)	12 (5.2%)	0.102
Portal vein tumor thrombus	22 (2.5%)	12 (5.2%)	0.051
Complete ablation	864 (97.8%)	226 (98.7%)	0.596

Continuous data are described by the median and interquartile range, and categorical variables by number and percentage. HBV: hepatitis B virus; HCV: hepatitis C virus; HCC: hepatocellular carcinoma.

Table 2. Baseline characteristics of groups 1–4 and pairwise comparison between groups 1–3 and group 4.

	Group 1	Group 2	Group 3	Group 4	p Value
N	313	330	170	70	–
Age (years)	49 (45–52)	60 (57–62)	69 (66–71)	78 (76–81)	<0.001
Sex (male)	274 (87.5%)***	269 (81.5%)**	127 (74.7%)	46 (65.7%)	<0.001
Nodule size (cm)	2.4 (1.8–3.3)***	2.4 (1.8–3.3)**	2.7 (1.9–3.5)	3.2 (2.2–4.1)	0.002
Number of nodules	2 (1–3)	2 (1–3)	2 (1–3)	2 (1–3)	0.680
Charlson comorbidity index	1 (0–2)***	2 (2–3)***	3 (3–4)***	4 (4–5)	<0.001
AFP
≥400 µg/L	51 (16.3%)	40 (12.1%)	34 (20.0%)	9 (12.9%)	0.108
Types of liver disease
HBV infection	277 (88.5%)***	277 (83.9%)***	124 (72.9%)*	40 (57.1%)	<0.001
HCV infection	21 (6.7%)***	35 (10.6%)**	29 (17.1%)	16 (22.9%)	<0.001
Alcoholic	4 (1.3%)	3 (0.9%)	1 (0.6%)	0 (0.0%)	0.727
Budd-Chiari syndrome	3 (1.0%)	1 (0.3%)	1 (0.6%)	1 (1.4%)	0.645
Ascites	19 (6.1%)	26 (7.9%)	10 (5.9%)	3 (4.3%)	0.620
PVTT	11 (3.5%)	7 (2.1%)	2 (1.2%)	2 (2.9%)	0.426
Extrahepatic metastasis	8 (2.6%)	10 (3.0%)	4 (2.4%)	4 (5.7%)	0.520
BCLC grade					0.490
0	40 (12.8%)	45 (13.6%)	20 (11.8%)	4 (5.7%)
A	167 (53.4%)	168 (50.9%)	81 (47.6%)	35 (50.0%)
B	88 (28.1%)	101 (30.6%)	63 (37.1%)	25 (35.7%)
C	17 (5.4%)	16 (4.8%)	6 (3.5%)	6 (8.6%)
D	1 (0.3%)	0 (0.0%)	0 (0.0%)	0 (0.0%)
Child Pugh grade					0.630
A	304 (97.1%)	318 (96.4%)	161 (94.7%)	68 (97.1%)
B	8 (2.6%)	12 (3.6%)	9 (5.3%)	2 (2.9%)
C	1 (0.3%)	0 (0.0%)	0 (0.0%)	0 (0.0%)
ALBI	***	***			<0.001
1	184 (58.8%)	188 (57.0%)	71 (41.8%)	23 (32.9%)
2	123 (39.3%)	136 (41.2%)	98 (57.6%)	47 (67.1%)
3	6 (1.9%)	6 (1.8%)	1 (0.6%)	0 (0.0%)
MELD score	8 (7–9)	8 (7–9)	8 (7–9)	8 (6–8)	0.112
Frequency of microwaves					0.495
2450 MHz	309 (98.7%)	329 (99.7%)	169 (99.4%)	69 (98.6%)
915 MHz	4 (1.3%)	1 (0.3%)	1 (0.6%)	1 (1.4%)
Number of antennas	2 (1–2)	2 (2–2)	2 (2–2)	2 (2–2)	0.071
Output power (W)	50 (50–50)	50 (50–60)	50 (50–60)	50 (50–50)	0.682
Total ablation time (s)	480 (360–600)	480 (360–720)	450 (360–705)	540 (360–885)	0.116

Continuous data are described by the median and interquartile range, and categorical variables by number and percentage.*,**,*** denotes pairwise significant difference compared to group 4 (p < 0.05, 0.01, 0.001). AFP: alpha-fetoprotein; HBV: hepatitis B virus; HCV: hepatitis C virus; PVTT: portal vein tumor thrombus; BCLC: Barcelona Clinic Liver Cancer grade; ALBI: albumin–bilirubin grade; MELD: Model for End-Stage Liver Disease score; HCC: hepatocellular carcinoma.

Table 3. Prognostic outcomes for groups 1–4.

	Group 1	Group 2	Group 3	Group 4	p Value
Short-term outcomes
Complete ablation	306 (97.8%)*	326 (98.8%)**	165 (97.1%)	65 (92.9%)	0.029
Major complications	10 (3.2%)	12 (3.6%)	2 (1.2%)	4 (5.7%)	0.271
Total hospital stay (days)	10 (8–13)***	11 (8–14)***	11 (8–15)***	14 (11–17)	<0.001
Post-ablation hospital stay (days)	5 (4–7)***	5 (4–7)***	5 (4–7)***	7 (5–9)	<0.001
Cost of hospitalization (thousand RMB yuan)	41 (35–47)***	41 (35–47)***	42 (37–50)*	45 (40–52)	<0.001
Long-term outcomes
Rate of death	25.2%*	27.9%*	39.4%	40.0%	0.002
Rate of tumor-specific death	21.4%*	23.0%	33.5%	32.9%	0.009
Median OS	45.9 (26.8–66.7)**	42.1 (26.3–58.4)*	37.2 (21.9–54.8)	31.9 (21.3–51.5)	<0.001 (Log rank P < 0.001)
Rate of progression	60.4%	60.9%	62.4%	58.6%	0.952
Median PFS	20.8 (8.5–39.0)	18.5 (6.6–37.0)	16.1 (8.0–30.2)	15.8 (5.2–30.1)	0.080 (Log rank P = 0.526)

*,**,*** denotes pairwise significant difference compared to group 4 (p < 0.05, 0.01, 0.001). OS: overall survival; PFS: progression-free survival.

Figure 1. The cumulative overall survival of group 1 (<55 years), group 2 (55–64 years), group 3 (65–74 years), and group 4 (≥75 years). The log rank test showed a significant difference among the 4 groups (p < 0.001). Pairwise statistical difference existed between group 1, 2 and 4 (p = 0.002, 0.013).

Table 4. Baseline characteristics of Group Y (<75 years) and Group S (≥75 years).

	Pre-propensity			Post-propensity
	Group Y	Group S	p Value	Group Y	Group S	p Value
N	813	70	–	70	70	–
Age (years)	57 (51–63)	78 (76–81)	<0.001	61 (51–67)	78 (76–81)	<0.001***
Sex (male)	670 (82.4%)	46 (65.7%)	<0.001	42 (60.0%)	46 (65.7%)	0.484
Nodule size (cm)	2.5 (1.8–3.4)	3.2 (2.2–4.1)	0.001	3.0 (2.0–4.1)	3.2 (2.2–4.1)	0.521
Number of nodules	2 (1–3)	2 (1–3)	0.523	2 (1–4)	2 (1–3)	0.887
Charlson comorbidity index	2 (1–3)	4 (4–5)	<0.001	2 (1–4)	4 (4–5)	<0.001
Diabetes	158 (19.4%)	20 (28.6%)	0.067	12 (17.1%)	20 (28.6%)	0.107
Cardiovascular diseases	209 (25.7%)	37 (52.9%)	<0.001	18 (25.7%)	37 (52.9%)	0.001
Pneumopathy	14 (1.7%)	0 (0.0%)	0.618	0 (0.0%)	0 (0.0%)	1.000
AFP	10.6 (3.5–122.5)	25.7 (3.6–157.3)	0.434	12.8 (3.8–104.0)	25.7 (3.6–157.3)	0.564
≥400 µg/L	125 (15.4%)	9 (12.9%)	0.570	11 (15.7%)	9 (12.9%)	0.629
Types of liver disease
HBV infection	678 (83.4%)	40 (57.1%)	<0.001	36 (51.4%)	40 (57.1%)	0.497
HCV infection	85 (10.5%)	16 (22.9%)	0.005	18 (25.7%)	16 (22.9%)	0.693
Alcoholic	8 (1.0%)	0 (0.0%)	1.000	2 (2.9%)	0 (0.0%)	0.496
Budd-Chiari syndrome	5 (0.6%)	1 (1.4%)	0.392	3 (4.3%)	1 (1.4%)	0.620
Ascites	55 (6.8%)	3 (4.3%)	0.614	5 (7.1%)	3 (4.3%)	0.718
PVTT	20 (2.5%)	2 (2.9%)	0.691	0 (0.0%)	2 (2.9%)	0.496
Extrahepatic metastasis	22 (2.7%)	4 (5.7%)	0.144	2 (2.9%)	4 (5.7%)	0.681
BCLC grade			0.280			0.268
0	105 (12.9%)	4 (5.7%)		9 (12.9%)	4 (5.7%)
A	416 (51.2%)	35 (50.0%)		34 (48.6%)	35 (50.0%)
B	252 (31.0%)	25 (35.7%)		25 (35.7%)	25 (35.7%)
C	39 (4.8%)	6 (8.6%)		2 (2.9%)	6 (8.6%)
D	1 (0.1%)	0 (0.0%)		0 (0.0%)	0 (0.0%)
Child Pugh grade			1.000			1.000
A	783 (96.3%)	68 (97.1%)		67 (95.7%)	68 (97.1%)
B	29 (3.6%)	2 (2.9%)		3 (4.3%)	2 (2.9%)
C	1 (0.1%)	0 (0.0%)		0 (0.0%)	0 (0.0%)
ALBI			<0.001			0.267
1	443 (54.5%)	23 (32.9%)		28 (40.0%)	23 (32.9%)
2	357 (43.9)	47 (67.1%)		40 (57.1%)	47 (67.1%)
3	13 (1.6%)	0 (0.0%)		2 (2.9%)	0 (0.0%)
MELD score	8 (7–9)	8 (6–8)	0.083	8 (7–9)	8 (6–8)	0.682
Frequency of microwaves			0.440			1.000
2450 MHz	807 (99.3%)	69 (98.6%)		68 (97.1%)	69 (98.6%)
915 MHz	6 (0.7%)	1 (1.4%)		2 (2.9%)	1 (1.4%)
Number of antennas	2 (2–2)	2 (2–2)	0.063	2 (2–2)	2 (2–2)	0.306
Output power (W)	50 (50–60)	50 (50–50)	0.271	50 (50–50)	50 (50–50)	0.967
Total ablation time (s)	480 (360–720)	540 (360–885)	0.021	480 (360–825)	540 (360–885)	0.467

Continuous data are described by the median and interquartile range, and categorical variables by number and percentage. AFP: alpha-fetoprotein; HBV: hepatitis B virus; HCV: hepatitis C virus; PVTT: portal vein tumor thrombus; BCLC: Barcelona Clinic Liver Cancer grade; ALBI: albumin–bilirubin grade; MELD: Model for End-Stage Liver Disease score; HCC: hepatocellular carcinoma.

Table 5. Prognostic outcomes before and after matching.

	Group Y	Group S	p Value	Group Y	Group S	p Value
Short-term outcomes
Complete ablation	797 (98.0%)	65 (92.9%)	0.020	67 (95.7%)	65 (92.9%)	0.718
Major complications	24 (3.0%)	4 (5.7%)	0.270	4 (5.7%)	4 (5.7%)	1.000
Total hospital stay (days)	10 (8–14)	14 (11–17)	<0.001	12 (9–15)	14 (11–17)	0.011
Post-ablation hospital stay (days)	5 (4–7)	7 (5–9)	<0.001	5 (3–8)	7 (5–9)	<0.001
Cost of hospitalization  (thousand RMB yuan)	41 (35–48)	45 (40–52)	<0.001	43 (37–51)	45 (40–52)	0.124
Long-term outcomes
Rate of death	29.3%	40.0%	0.061	40.0%	40.0%	1.000
Rate of tumor-specific death	24.6%	32.9%	0.127	37.1%	32.9%	0.595
Median OS	42.4 (25.7–61.0)	31.9 (21.3–51.5)	Log rank P = 0.014	39.4 (21.8–57.1)	31.9 (21.3–51.5)	Log rank P = 0.784
Rate of progression	61.0%	58.6%	0.689	52.9%	58.6%	0.496
Median PFS	18.9 (7.6–36.0)	15.8 (5.2–30.1)	Log rank P = 0.435	19.6 (11.2–41.6)	15.8 (5.2–30.1)	Log rank P = 0.186

OS: overall survival; PFS: progression-free survival.

Figure 2. The cumulative overall survival of Group Y (<75 years) and Group S (≥75 years) after propensity matching. The log rank test showed no significant difference between the two groups (p = 0.784).

Table 6. Univariate and multivariate Cox regression analyses of overall survival of the patients from Group Y and S.

	Univariate				Multivariate
	HR	95% CI		p Value	HR	95% CI		p Value
		Inferior	Superior			Inferior	Superior
Age (years)	1.01	0.99	1.03	0.296
Sex (male)	1.18	0.68	2.04	0.556
Nodule size (cm)	1.25	1.12	1.40	<0.001	1.24	1.09	1.40	<0.001
Number of nodules	1.03	0.93	1.13	0.587
Charlson comorbidity index	1.09	0.95	1.25	0.228
Other cancer	4.84	1.48	15.86	0.009	6.37	1.91	21.21	0.003
AFP ≥400 µg/L	1.45	0.73	2.88	0.285
Ascites	1.45	0.45	4.65	0.537
Extrahepatic metastasis	1.73	0.63	4.81	0.290
Child Pugh grade	3.43	1.23	9.61	0.019	4.10	1.46	11.54	0.008
ALBI	1.27	0.75	2.15	0.375
MELD score	0.93	0.86	1.00	0.059
Frequency of MW (vs 2450 MHz)	7.62	2.32	25.08	<0.001	4.55	1.29	16.07	0.019
Number of antennas	1.04	0.77	1.40	0.815
Output power (W)	1.03	0.98	1.09	0.274
Total ablation time (s)	1.00	1.00	1.00	0.601

AFP: alpha-fetoprotein; ALBI: albumin–bilirubin grade; MELD: Model for End-Stage Liver Disease score.