Long-term efficacy of microwave ablation in the treatment of subcapsular hepatocellular carcinomas of ≤3 cm in diameter: a multicenter, propensity score-matched study

Figures & data

Figure 1. Flowchart of patients in the study.

Figure 2. Cumulative OS and DFS of the subcapsular and non-subcapsular groups before PSM.

Table 1. Baseline characteristics of patients before and after propensity score matching.

Characteristics	Unmatched cohort			Propensity score-matched cohort
	Subcapsular	Non-subcapsular	p	Subcapsular	Non-subcapsular	p
	(n = 143)	(n = 287)		(n = 142)	(n = 142)
Sex (male/ female)	113/30	234/53	0.534	112/30	111/31	0.885
Mean age(year)^a	54.83 ± 10.25	55.94 ± 11.65	0.335	54.86 ± 10.28	55.27 ± 12.51	0.760
aCCI^a	1.73 ± 1.48	1.78 ± 1.44	0.774	1.72 ± 1.48	1.82 ± 1.50	0.577
Etiology (Nor/HBV/HCV/others)	17/103/20/3	54/213/14/6	0.005	17/102/20/3	21/105/13/3	0.583
Cirrhosis (%)	88.1% (126/143)	81.2% (233/287)	0.068	88.0% (125/142)	85.2% (121/142)	0.486
Tumor number (1/2/3)	121/20/2	234/44/9	0.509	120/20/2	118/17/7	0.219
Tumor size (cm)^a	2.15 ± 0.55	2.04 ± 0.55	0.073	2.15 ± 0.55	2.12 ± 0.54	0.664
ALT (U/L)	28.6[7.7,185.3]	30.0[7.9,199.2]	0.241	28.6[7.7,185.3]	29.3[7.9,174.8]	0.616
AST (U/L)	28.0[9.0,153.3]	27.0[9.7,157.0]	0.849	28.0[9.0,153.3]	26.0[11.0,129.6]	0.692
GGT (U/L)	40.2[10.0,534.7]	45.0[6.0,619.0]	0.333	40.2[10.0,534.7]	46.6[6.0,619.0]	0.694
AFP > 200 μg/L (%)	22.4% (32/143)	22.3% (64/287)	0.985	22.5% (32/142)	23.2% (33/142)	0.888
ALB (g/L)	40.45[2.61,51.6]	40.0[23.6,52.9]	0.841	40.45[2.61,51.6]	39.90[28.5,50.0]	0.650
TBIL (μmol/L)	14.58[4.66,48.60]	14.78[3.10,56.40]	0.532	14.58[4.66,48.60]	15.18[4.30,35.90]	0.311
DBIL (μmol/L)	4.95[0.57,29.4]	5.10[1.20,39.00]	0.517	4.95[0.57,29.4]	5.20[1.20,27.30]	0.523
GLU (mmol/L)	4.86[3.72,10.00]	5.15[2.94,13.90]	0.026	4.86[3.72,10.00]	4.99[3.20,11.90]	0.476
Hb (g/L)^a	135.29 ± 16.98	139.03 ± 18.71	0.044	135.48 ± 16.89	137.62 ± 19.94	0.329
PLT (×10^9/L)^a	126.59 ± 62.78	127.67 ± 61.01	0.864	126.63 ± 63.01	131.38 ± 63.15	0.527
RBC (×10^9/L)^a	4.36 ± 0.66	4.47 ± 0.65	0.104	4.37 ± 0.66	4.45 ± 0.69	0.290
PT (s)^a	14.08 ± 1.96	13.92 ± 1.56	0.353	14.09 ± 1.96	13.83 ± 1.38	0.199

aCCI: age-adjusted Charlson comorbidity index; HBV: hepatitis B virus; HCV: hepatitis C virus; ALT: alanine aminotransferase; AST: aspartate aminotransferase; GGT: gamma-glutamyl transferase; AFP: alpha-fetoprotein; ALB: albumin; TBIL: total bilirubin; DBIL: direct bilirubin; GLU: blood glucose; Hb: hemoglobin; PLT: platelet; RBC: red blood cell; PT: prothrombin time.

^aThese data are presented as means ± standard deviation; other values are presented as numbers of patients or medians [25th–75th percentile].

Figure 3. Cumulative OS and DFS of the subcapsular and non-subcapsular groups after PSM.

Table 2. Perioperative outcomes of patients in the subcapsular and non-subcapsular groups.

Variables	Subcapsular(n = 142)	Non-subcapsular(n = 142)	p
Technical success rate	87.3% (124/142)	90.8% (129/142)	0.442
Total number of insertions	2.56 ± 1.31	2.46 ± 1.06	0.485
Postoperative hospital stays	6.15 ± 3.17	5.68 ± 2.37	0.150
Assistive technologies	60.9% (67/142)	39.1% (43/142)	0.003
Hydrodissection	20/142	9/142	0.031
Temperature monitoring	15/142	7/142	0.076
Ethanol injection	11/142	3/142	0.028
Image fusion technology	31/142	31/142	1.000
Total number of complications	21.8% (31/142)	27.5% (39/142)	0.271
Total number of major complications	6.3% (9/142)	4.2% (6/142)	0.426
Needle way seeding	2	0
Pleural effusion, thoracocentesis	1	1
Postoperative infection	2	0
Inferior vena cava thrombosis	0	1
Technique effectiveness	96.5% (137/142)	93.7% (133/142)	0.273
Local tumor progression	4.2% (6/142)	4.2% (6/142)	1.000

Data are presented as means ± standard deviation or percentages.

Figure 4. Cumulative DFS in subgroups with HCC diameters of ≤2 cm and 2–3 cm in the matched cohort.

Table 3. Univariate and multivariate analyses of overall survival after PSM.

Parameters	Univariate analysis			Multivariate analysis
	HR (95% CI)		p	HR (95% CI)		p
Sex (male)	0.537	(0.185, 1.555)	0.251
Age (>60year)	9.308	(2.894, 29.939)	0.000	6.552	(3.040, 14.118)	0.000
aCCI（>3）	0.996	(0.322, 3.084)	0.994
Number of tumors (>1)	1.148	(0.453, 2.910)	0.771
Tumor size (>2.0 cm)	2.701	(1.006, 7.257)	0.049	2.410	(1.024, 5.673)	0.044
Cirrhosis (yes)	0.945	(0.310, 2.881)	0.920
ALT (>40 U/L)	0.298	(0.081, 1.093)	0.068
AST (>40 U/L)	1.460	(0.443, 4.809)	0.534
GGT (>50 U/L)	2.910	(0.923, 9.173)	0.068
AFP (>200μg/L)	1.509	(0.506, 4.500)	0.461
ALB (>35 g/L)	1.981	(0.528, 7.434)	0.311
TBIL (>21μmol/L)	1.631	(0.379, 7.020)	0.511
DBIL (>8.6 μmol/L)	5.574	(1.255, 24.754)	0.024	3.709	(1.766, 7.791)	0.001
GLU (>6.1 mmol/L)	0.309	(0.085, 1.125)	0.075
Hb (<120 g/L)	3.767	(1.277, 11.110)	0.016	2.995	(1.415, 6.339)	0.004
PLT (<100 × 10^9/L)	0.343	(0.117, 1.010)	0.052
RBC (<4.3 × 10^9/L)	1.486	(0.489, 4.518)	0.485
PT (<13 s)	0.670	(0.246, 1.826)	0.434
Completely ablation(no)	2.194	(0.491, 9.804)	0.304
Local tumor progression(yes)	3.831	(0.535, 27.436)	0.181
Intrahepatic metastasis(yes)	3.529	(1.354, 9.196)	0.010	3.372	(1.618, 7.024)	0.001
Extrahepatic metastasis(yes)	8.199	(2.881, 23.338)	0.000	4.047	(1.855, 8.829)	0.000
Subcapsular location(yes)	0.926	(0.380, 2.255)	0.866
Hydrodissection (yes)	0.499	(0.082, 3.051)	0.452
Temperature monitoring(yes)	19.834	(4.773, 82.423)	0.000	6.380	(2.558, 15.913)	0.000
Ethanol injection(yes)	0.701	(0.185, 2.649)	0.600
Image fusion (yes)	1.116	(0.332, 3.755)	0.859

HR: hazard ratio; CI: confidence interval; aCCI: age-adjusted Charlson comorbidity index; ALT: alanine aminotransferase; AST: aspartate aminotransferase; GGT: gamma-glutamyl transferase; AFP: alpha-fetoprotein; ALB: albumin; TBIL: total bilirubin; DBIL: direct bilirubin; GLU: blood glucose; Hb: hemoglobin; PLT: platelet; RBC: red blood cell; PT: prothrombin time.

Table 4. Univariate and multivariate analyses of disease-free survival after PSM.

Parameters	Univariate Analysis			Multivariate Analysis
	HR (95% CI)		p	HR (95% CI)		p
Sex (male)	1.146	(0.681, 1.928)	0.609
Age (>60 year)	0.936	(0.572, 1.533)	0.793
aCCI (>3)	2.368	(1.299, 4.317)	0.005	1.839	(1.149, 2.943)	0.011
Number of tumors (>1)	2.988	(1.902, 4.694)	0.000	2.935	(1.939, 4.443)	0.000
Tumor size (>2.0 cm)	1.211	(0.791, 1.854)	0.378
Cirrhosis (yes)	1.046	(0.567, 1.930)	0.885
ALT (>40 U/L)	0.985	(0.591, 1.641)	0.953
AST (>40 U/L)	0.958	(0.545, 1.684)	0.882
GGT (>50 U/L)	1.200	(0.764, 1.884)	0.429
AFP (>200 μg/L)	1.043	(0.658, 1.654)	0.857
ALB (>35 g/L)	0.587	(0.317, 1.084)	0.089
TBIl (>21 μmol/L)	0.718	(0.306, 1.685)	0.447
DBIl (>8.6 μmol/L)	1.944	(0.776, 4.868)	0.156
GLU (>6.1 mmol/L)	0.676	(0.368, 1.240)	0.206
Hb (<120 g/L)	0.945	(0.512, 1.746)	0.858
PLT (<100 × 10^9/L)	1.191	(0.746, 1.900)	0.464
RBC (<4.3 × 10^9/L)	0.590	(0.360, 0.967)	0.036
PT (<13 s)	1.250	(0.785, 1.990)	0.347
Completely ablation (no)	0.582	(0.200, 1.691)	0.320
Subcapsular location (yes)	1.291	(0.877, 1.899)	0.196
Hydrodissection (yes)	0.494	(0.230, 1.063)	0.071
Temperature monitoring (yes)	0.691	(0.291, 1.640)	0.402
Ethanol injection (yes)	1.068	(0.402, 2.840)	0.895
Image fusion (yes)	0.785	(0.483, 1.275)	0.328

HR: hazard ratio; CI: confidence interval; aCCI: age-adjusted Charlson comorbidity index; ALT: alanine aminotransferase; AST: aspartate aminotransferase; GGT: gamma-glutamyl transferase; AFP: alpha-fetoprotein; ALB: albumin; TBIL: total bilirubin; DBIL: direct bilirubin; GLU: blood glucose; Hb: hemoglobin; PLT: platelet; RBC: red blood cell; PT: prothrombin time.