Risk factors and a predictive nomogram for lymph node metastasis in superficial esophageal squamous cell carcinoma

Table 2 Comparisons of clinicopathological characteristics between lymph node metastasis positive and lymph node metastasis negative group

Variable	Training set (n = 332)		P value	Validation set (n = 142)		P value
	LNM(-)	LNM(+)		LNM(-)	LNM(+)
Gender			0.298			0.913
Male	201	51		84	20
Female	68	12		31	7
Age (yr), median (range)	60 (42-80)	60 (45-84)	0.204	60 (38-78)	58 (47-76)	0.522
Tumor size, (cm), mean ± SD	2.23 ± 1.21	2.65 ± 0.99	0.008	2.07 ± 0.97	2.61 ± 0.86	0.008
Tumor location, n (%)			0.095			0.702
Upper third	14	6		7	1
Middle third	181	47		62	13
Lower third	74	10		46	13
Paris classification, n (%)			0.282			0.158
0-I	46	14		26	9
0-II	186	37		74	12
0-III	37	12		15	6
Depth of invasion, n (%)			< 0.001			< 0.001
MM	100	3		47	2
SM1	53	6		19	2
> SM1	116	54		49	23
Differentiation, n (%)			0.015			0.029
Well	77	8		15	3
Moderate	148	38		80	13
Poor	44	17		20	11
INF pattern, n (%)			0.001			0.014
INF-a	125	13		53	5
INF-b	123	41		52	16
INF-c	21	9		10	6
Tumor budding, n (%)			0.009			0.009
No	241	48		103	18
Low	19	8		8	5
High	9	7		4	4
LVI, n (%)			0.005			0.004
Yes	10	8		4	5
No	259	55		111	22

LNM: Lymph node metastasis; MM: Muscularis mucosae; SM1: Upper third of submucosa; INF pattern: Infiltrative growth pattern; LVI: Lymphovascular invasion.