Relationship between subgroups of central and lateral lymph node metastasis in clinically node-negative papillary thyroid carcinoma

Table 1 Clinicopathological characteristics and univariate analysis of lymph node metastasis in ipsilateral level-II, level-III, level-IV and lateral lymph nodes

Clinicopathological factor		Lateral lymph node metastasis			Ipsilateral lymph node metastasis level II			Ipsilateral lymph node metastasis level III			Ipsilateral lymph node metastasis level IV
		Positive, n = 181	Negative, n = 207	P value	Positive, n = 77	Negative, n = 311	P value	Positive, n = 126	Negative, n = 262	P value	Positive, n = 104	Negative, n = 284	P value
Age (yr)	< 55	147 (81.2)	169 (81.6)	0.914	59 (76.6)	257 (82.6)	0.224	101 (80.2)	215 (82.1)	0.652	87 (87.3)	229 (80.6)	0.498
	≥ 55	34 (18.8)	38 (18.4)		18 (23.4)	54 (17.4)		25 (19.8)	47 (17.9)		17 (16.3)	55 (19.4)
Sex	Female	118 (65.2)	154 (74.4)	0.048	44 (57.1)	228 (73.3)	0.006	85 (67.5)	187 (71.4)	0.430	70 (67.3)	202 (71.1)	0.467
	Male	63 (34.8)	53 (25.6)		33 (42.9)	83 (26.7)		41 (32.5)	75 (28.6)		34 (32.7)	82 (28.9)
Primary tumor size	> 2 cm	44 (24.3)	21 (10.1)	< 0.001	24 (31.2)	41 (13.2)	< 0.001	32 (25.4)	33 (12.6)	0.002	29 (27.9)	36 (12.7)	< 0.001
	≤ 2 cm	137 (75.7)	186 (89.9)		53 (68.8)	270 (86.8)		94 (74.6)	229 (87.4)		75 (72.1)	248 (873)
Tumor location	UP	57 (31.5)	45 (21.7)	0.029	31 (40.3)	71 (22.8)	0.002	38 (30.2)	64 (24.4)	0.230	28 (26.9)	74 (26.1)	0.864
	Non-UP	124 (68.5)	162 (78.3)		46 (59.7)	240 (77.2)		88 (69.8)	198 (75.6)		76 (73.1)	210 (73.9)
Multifocality	Yes	27 (14.9)	21 (10.1)	0.154	15 (19.5)	33 (10.6)	0.034	19 (15.1)	29 (11.1)	0.261	17 (16.3)	31 (10.9)	0.150
	No	154 (85.1)	186 (89.9)		62 (80.5)	278 (89.4)		107 (84.9)	233 (88.91)		87 (83.7)	253 (89.1)
ETE	Yes	78 (43.1)	58 (28.0)	0.002	38 (49.4)	98 (31.5)	0.003	54 (42.9)	82 (31.3)	0.025	52 (50.01)	84 (29.6)	< 0.001
	No	103 (56.9)	149 (72.0)		39 (50.6)	213 (68.5)		72 (57.1)	180 (68.7)		52 (50.0)	200 (70.4)
HT	Yes	36 (19.9)	44 (21.3)	0.740	11 (14.3)	69 (22.2)	0.125	28 (22.2)	52 (19.8)	0.344	21 (20.2)	59 (20.8)	0.900
	No	145 (80.1)	163 (78.7)		66 (85.7)	242 (77.8)		88 (77.8)	210 (80.2)		83 (79.8)	225 (79.2)
CLNM	0	17 (9.4)	86 (41.5)	< 0.001	10 (13.0)	93 (29.9)	< 0.001	14 (11.1)	89 (34.0)	< 0.001	6 (5.8)	97 (34.2)	< 0.001
	1-2	45 (24.9)	65 (31.4)		18 (23.4)	92 (29.6)		30 (23.8)	80 (30.5)		22 (21.2)	88 (31.0)
	≥ 3	119 (65.7)	56 (27.1)		49 (63.6)	126 (40.5)		82 (65.1)	93 (35.5)		76 (73.1)	99 (34.9)
Prelaryngeal LNM	0	113 (62.4)	180 (87.0)	< 0.001	44 (57.1)	249 (80.1)	< 0.001	82 (65.1)	21 (80.5)	0.001	66 (63.5)	37 (79.9)	< 0.001
	1-2	62 (34.3)	25 (12.1)		29 (37.7)	58 (18.6)		38 (30.2)	49 (18.7)		36 (34.6)	51 (18.0)
	≥ 3	6 (3.30)	2 (1.00)		4 (5.2)	4 (1.3)		6 (4.8)	2 (0.8)		2 (1.9)	6 (2.1)
Pretracheal LNM	0	65 (35.9)	134 (64.7)	< 0.001	32 (41.6)	167 (53.7)	0.121	41 (32.5)	158 (60.3)	< 0.001	33 (31.7)	166 (58.5)	0.002
	1-2	60 (29.0)	74 (40.9)		30 (39.0)	104 (33.4)		51 (40.5)	83 (31.7)		47 (45.2)	87 (30.6)
	≥ 3	42 (23.2)	13 (6.3)		15 (19.5)	40 (12.9)		34 (27.0)	21 (8.0)		24 (23.1)	31 (10.9)
Ipsilateral paratracheal LNM	0	46 (25.4)	121 (58.5)	< 0.001	20 (26.0)	147 (47.3)	< 0.001	36 (28.6)	131 (50.0)	< 0.001	20 (19.2)	147 (51.8)	< 0.001
	1-2	73 (40.3)	64 (30.9)		26 (33.8)	111 (35.7)		42 (33.3)	95 (36.3)		45 (43.3)	92 (32.4)
	≥ 3	62 (34.3)	22 (10.6)		31 (40.3)	53 (17.0)		48 (38.1)	36 (13.7)		39 (37.5)	45 (15.8)

HT: Hashimoto’s thyroid; PTC: Papillary carcinoma; ETE: Extrathyroid extension; CLNM: Central lymph node metastasis; LNM: Lymph node metastasis; UP: Tumors located in the upper lobe of the thyroid gland; Non-UP: Tumors located in the middle lobe, lower lobe, isthmus and whole.

Table 2 Optimal scale regression analysis of lateral lymph node metastasis

Variable	Beta	Standardized coefficient std. error	Df	F	Sig	Tolerance		Importance
						After transformation	Before transformation
Sex	0.007	0.028	1	0.058	0.809	0.911	0.911	0.003
Primary tumor size	0.132	0.045	1	8.477	0.004	0.958	0.956	0.104
Tumor location	0.119	0.044	1	7.449	0.007	0.974	0.975	0.055
ETE	0.076	0.043	1	3.153	0.077	0.959	0.959	0.049
Prelaryngeal LNM	0.142	0.049	1	8.338	0.004	0.879	0.871	0.168
Pretracheal LNM	0.197	0.051	1	14.773	0.000	0.836	0.831	0.260
Ipsilateral paratracheal LNM	0.239	0.049	1	23.330	0.000	0.794	0.798	0.382

PTC: Papillary carcinoma; ETE: Extrathyroid extension; LNM: Lymph node metastasis.

Table 3 Optimal scale regression analysis of ipsilateral level-II lymph node metastasis

Variable	Beta	Standardized coefficient std. error	Df	F	Sig	Tolerance		Importance
						After transformation	Before transformation
Sex	0.119	0.053	1	5.029	0.026	0.913	0.913	0.122
Primary tumor size	0.153	0.058	1	7.033	0.008	0.954	0.954	0.213
Tumor location	0.150	0.055	1	7.298	0.007	0.984	0.984	0.172
Multifocality	0.048	0.042	1	1.321	0.251	0.963	0.963	0.038
ETE	0.101	0.051	1	4.005	0.046	0.964	0.964	0.110
Prelaryngeal LNM	0.142	0.060	1	5.668	0.004	0.907	0.906	0.227
Ipsilateral paratracheal LNM	0.239	0.047	1	3.319	0.069	0.859	0.859	0.119

ETE: Extrathyroid extension; LNM: Lymph node metastasis.

Table 4 Optimal scale regression analysis of ipsilateral level-III lymph node metastasis

Variable	Beta	Standardized coefficient std. error	Df	F	Sig	Tolerance		Importance
						After transformation	Before transformation
Primary tumor size	0.121	0.050	1	5.833	0.016	0.968	0.961	0.120
ETE	0.051	0.042	1	1.528	0.217	0.965	0.963	0.036
Prelaryngeal LNM	0.079	0.049	1	2.569	0.078	0.935	0.876	0.084
Pretracheal LNM	0.216	0.054	1	16.140	0.000	0.874	0.849	0.408
Ipsilateral paratracheal LNM	0.200	0.056	1	12.686	0.000	0.905	0.836	0.351

ETE: Extrathyroid extension; LNM: Lymph node metastasis.

Table 5 Optimal scale regression analysis of ipsilateral level-IV lymph node metastasis

Variable	Beta	Standardized coefficient std. error	Df	F	Sig	Tolerance		Importance
						After transformation	Before transformation
Primary tumor size	0.150	0.051	1	8.730	0.003	0.975	0.961	0.164
ETE	-0.127	0.052	1	5.884	0.016	0.962	0.963	0.146
Prelaryngeal LNM	-0.071	0.046	1	2.357	0.126	0.973	0.876	0.003
Pretracheal LNM	0.149	0.055	1	7.415	0.001	0.884	0.849	0.216
Ipsilateral paratracheal LNM	0.251	0.049	1	26.079	0.000	0.889	0.846	0.472

ETE: Extrathyroid extension; LNM: Lymph node metastasis.