Risk of lymph node metastasis in mixed-type early gastric cancer determined by the extent of the poorly differentiated component

Table 1 Clinicopathological factors and lymph node metastasis in early gastric cancers n (%)

	Total	Lymph node status		P value
		Negative(n = 479)	Positive(n = 71)
Sex				0.950
Male	304	265 (87.2)	39 (12.8)
Female	246	214 (87.0)	32 (13.0)
Age (yr)	550	54.5 ± 0.7	55.5 ± 2.5	0.686
Site1				0.059
Upper	129	120 (93.0)	9 (7.0)
Middle	252	217 (86.1)	35 (13.9)
Lower	169	142 (84.0)	27 (16.0)
Gross type				0.030
Elevated	59	45 (76.3)	14 (23.7)
Flat	51	46 (90.2)	6 (9.8)
Depressed	440	388 (88.2)	52 (11.8)
Ulceration				0.640
Absent	445	389 (87.4)	56 (12.6)
Present	105	90 (85.7)	15 (14.3)
Tumour size (cm)2				< 0.0001
≤ 1	40	39 (97.5)	1 (2.5)
≤ 2	126	120 (95.2)	6 (4.8)
≤ 3	141	125 (88.7)	16 (11.3)
≤ 3	243	195 (80.2)	48 (19.8)
Depth of invasion3				< 0.0001
Mucosa	288	273 (94.8)	15 (5.2)
M2	50	49 (98.0)	1 (2.0)
M3	238	224 (94.1)	14 (5.9)
Submucosa	262	206 (78.6)	56 (21.4)
SM1	33	30 (90.9)	3 (9.1)
SM2	67	55 (82.1)	12 (17.9)
SM3	162	121 (74.7)	41 (25.3)
Depth (μm)	262	1754 ± 89.4	2017 ± 130.3	0.153
Perineural invasion				< 0.0001
Absent	495	442 (89.3)	53 (10.7)
Present	55	37 (67.3)	18 (32.7)
LV invasion				< 0.0001
Absent	518	464 (89.6)	54 (10.4)
Present	32	15 (46.9)	17 (53.1)

¹Between upper vs middle+lower;

²Between ≤ 2 cm vs > 2 cm;

³Between M vs SM. LV: Lymphovascular; M2: Lamina propria invasion; M3: Muscularis mucosae invasion without penetration; SM1: Upper third; SM2: Middle third; SM3: Lower third.

Table 2 Lymph node metastasis according to depth of invasion, ulceration, and tumour size n (%)

	Mucosal carcinoma				Submucosal carcinoma
	No ulcer		Ulcer		SM1		SM2	SM3
	≤2 cm	> 2 cm	≤3 cm	> 3 cm	≤3 cm	> 3 cm	Any size
Diffuse (n = 302)	1/61 (1.6)	5/86 (5.8)	2/22 (9.0)	1/19 (5.3)	0/12 (0)	2/7 (28.6)	6/32 (18.8)	11/63 (17.5)
Mixed (n = 248)	0/19 (0)	5/64 (7.8)	0/4 (0)	1/10 (10)	0/6 (0)	1/8 (12.5)	6/35 (17.1)	30/99 (30.3)
Total (n = 550)	1/80 (1.3)	10/150 (6.7)	2/26 (7.7)	2/29 (6.9)	0/18 (0)	3/15 (20.0)	12/67 (17.9)	41/162 (25.3)

SM1: Upper third; SM2: Middle third; SM3: Lower third.

Table 3 Histopathological subtypes and lymph node metastasis n (%)

		Status of lymph node metastasis
	Total	Negative	Positive
Pure diffuse type	302	274 (90.7)	28 (9.3)a
Sig	233	210 (90.1)	23 (9.9)
Por	69	64 (92.8)	5 (7.2)
Mixed type	248	205 (83.7)	43 (16.3)
Predominantly diffuse	163	130 (79.8)	33 (20.2)a
Sig predominant	107	86 (80.4)	21 (19.6)
Por predominant	56	44 (78.6)	12 (21.4)
Predominantly intestinal	82	72 (87.8)	10 (12.2)a
Diffuse = intestinal	3	3 (100.0)	0 (0.0)

^aP = 0.003 (between pure diffuse, predominantly diffuse, and predominantly intestinal). Sig: Signet ring cell; Por: Poorly differentiated.

Table 4 Relationship between the extent of various histopathological components and lymph node metastasis in 550 diffuse- and mixed-type early gastric cancers

	Lymph node status
	Negative(n = 479)	Positive(n = 71)	P value
Total (cm)	3.30 ± 0.09	4.46 ± 0.29	< 0.001
Diffuse type (cm)	2.73 ± 0.11	3.61 ± 0.24	0.005
Signet ring cell	2.07 ± 0.12	2.54 ± 0.29	0.161
Poorly differentiated	0.66 ± 0.05	1.07 ± 0.20	0.012
Intestinal type (cm)	0.65 ± 0.05	0.87 ± 0.17	0.172