Prognostic value of number of examined lymph nodes in patients with node-negative gastric cancer

Table 1 Overall survival by total examined lymph nodes and cut-point analysis in each subgroup

Depth of invasion	≤ 3 vs≥ 4		≤ 10 vs≥ 11		≤ 15 vs≥ 16		≤ 25 vs≥ 26
	χ2	P value	χ2	P value	χ2	P value	χ2	P value
T1 + T2	8.333	0.004	9.679	0.002	11.023	0.001	0.825	0.364
T3 + T4	5.529	0.019	7.884	0.005	13.204	< 0.001	9.476	0.002
Total	8.711	0.003	16.589	< 0.001	20.612	< 0.001	5.770	0.016

Table 2 Comparison of clinicopathologic characteristics between patients with ≤ 15 and >15 examined lymph nodes n (%)

Variables	Number of examined nodes		χ2	P value
	≤ 15	> 15
Total	331 (66.6)	166 (33.4)
Gender			11.741	0.001
Male	259 (78.2)	106 (63.9)
Female	72 (21.8)	60 (36.1)
Age at surgery (yr)			5.355	0.023
≤ 60	155 (46.8)	96 (57.8)
> 60	176 (53.2)	70 (42.2)
Tumor size (cm)			0.845	0.392
≤ 4	163 (49.2)	89 (53.6)
> 4	168 (50.8)	77 (46.4)
Tumor location			8.672	0.034
Lower	158 (47.7)	98 (59.0)
Middle	31 (9.4)	16 (9.6)
Upper	111 (33.5)	35 (21.1)
Diffuse	31 (9.4)	17 (7.7)
Type of gastrectomy			4.455	0.041
Subtotal	284 (85.8)	130 (78.3)
Total	47 (14.2)	36 (21.7)
Histological type			9.694	0.002
Undifferentiated	177 (53.5)	113 (68.1)
Differentiated	154 (46.5)	53 (31.9)
Extent of lymphadenectomy			111.652	< 0.001
Limited	242 (73.6)	39 (23.6)
Extended	87 (26.4)	126 (76.4)
Extent of examined lymph nodes			84.522	< 0.001
Perigastric	189 (57.1)	23 (13.9)
Extragastric	142 (42.9)	143 (86.1)
Depth of invasion			1.445	0.695
T1	21 (6.3)	13 (7.8)
T2	59 (17.8)	35 (21.1)
T3	47 (14.2)	24 (14.5)
T4	204 (61.6)	94 (56.7)
TNM Classification 7th			1.738	0.784
Ia	21 (6.3)	13 (7.8)
Ib	59 (17.8)	35 (21.1)
IIa	47 (14.2)	24 (14.5)
IIb	196 (59.2)	89 (53.6)
IIIb	8 (2.4)	5 (3.0)

Table 3 Univariate and multivariate survival analyses of 497 node-negative gastric cancer patients

Variables	5-YSR	Univariate analysis		Multivariate analysis
		χ2	P value	HR (95%CI)	P value
Gender		1.213	0.271
Male	66.0
Female	70.4
Age at surgery (yr)		2.720	0.099
≤ 60	70.1
> 60	64.2
Tumor size (cm)		3.548	0.060
≤ 4	71.0
> 4	63.2
Tumor location		0.167	0.682
Upper	69.9
Middle	53.2
Lower	69.5
Diffuse	60.4
Type of gastrectomy		2.045	0.153
Subtotal	68.3
Total	61.4
Histological type		0.117	0.732
Undifferentiated	67.9
Differentiated	66.2
Extent of lymphadenectomy		6.093	0.014
Limited	63
Extended	73.2
Extent of examined lymph nodes (LNs)		12.112	0.001
Perigastric	58.9
Extragastric	73.3
Depth of invasion		22.355	< 0.001		< 0.001
T1	88.2			1
T2	79.8			1.801 (0.613-5.293)	0.285
T3	74.6			2.102 (0.703-6.287)	0.184
T4	59.1			4.066 (1.502-11.007)	0.006
Number of examined LNs		32.690	< 0.001	0.334 (0.221-0.506)	< 0.001
≤ 15	58.6			1
> 15	84.3			0.327 (0.216-0.495)	< 0.001
TNM Classification 7th		22.541	< 0.001
Ia	88.2
Ib	79.8
IIa	74.6
IIb	59.3
IIIb	53.8

5-YSR: 5-year survival rate; TNM: Tumour, node, metastasis.

Table 4 Five-year overall survival by T stage subgroups and total number of examined lymph nodes

Variables	Number of examined nodes (n)				χ2	P value
	1-3	4-10	11-15	≥ 16
Depth of invasion
T1	60.0%	91.7%	-	92.3%	4.598	0.204
T2	58.3%	68.2%	84.0%	91.4%	9.668	0.022
T3	50.0%	63.3%	81.8%	91.7%	8.738	0.033
T4	35.1%	48.6%	62.5%	78.7%	31.487	< 0.001
Total	43.3%	56.6%	71.8%	84.3%	51.837	< 0.001

Table 5 Recurrent sites of node-negative gastric cancer in terms of ≤ 15 and > 15 examined lymph nodes n (%)

Recurrent sites	Number of examined nodes		χ2	P value
	≤ 15	> 15
Recurrence			4.491	0.043
Yes	65 (19.6)	20 (12.0)
No	266 (80.4)	146 (88.0)
Locoregional recurrence			4.362	0.048
Yes	37 (11.2)	9 (5.4)
No	294 (88.8)	157 (94.6)
Peritoneal seeding			4.874	0.037
Yes	24 (7.3)	4 (2.4)
No	307 (92.7)	162 (97.6)
Hematogenous spread			1.740	0.239
Yes	24 (7.3)	7 (4.2)
No	307 (92.7)	159 (95.8)