Table 3.

Univariate and multivariate cox regression analyses of factors affecting survival of patients in the N+ group.

	Univariate			Multivariate
Variables	HR	95% CI	P	HR	95% CI	P
Sex
Male	Ref.				Ref.
Female	0.661	(0.517–0.844)	0.001	0.658	(0.514–0.842)	0.001
Age, years
<75	Ref.
≥75	1.679	(1.156–2.439)	0.006	1.882	(1.293–2.74)	0.001
Pathologic differentiation grade			0.068
Well G1	Ref.
Moderate G2	1.219	(0.939–1.584)	0.137
Poor or undifferentiated G3	1.351	(1.042–1.753)	0.023
Lymphovascular invasion
Yes		Ref.			Ref.
No	0.626	(0.524–0.749)	<0.001	0.644	(0.537–0.771)	<0.001
Nerve invasion
Yes		Ref.			Ref.
No	0.754	(0.624–0.912)	0.004	0.878	(0.723–1.066)	0.189
Tumor location			0.201
Upper	Ref.
Middle	1.195	(0.975–1.465)	0.086
Lower	1.081	(0.852–1.371)	0.521
Pathological T stage			<0.001			<0.001
T1b		Ref.			Ref.
T2	1.408	(0.86–2.307)	0.174	1.465	(0.893–2.401)	0.13
T3	2.154	(1.362–3.408)	0.001	2.077	(1.309–3.296)	0.002
TNM stage			<0.001		–
II		Ref.			–
III	0.174	(0.088–0.342)	<0.001		–
IV	0.528	(0.433–0.643)	<0.001		–
Thoracic surgery
MIE		Ref.
OE	1.058	(0.975–1.148)	0.176
Abdominal surgery
MIE		Ref.
OE	1.062	(0.975–1.156)	0.167
The number of LN resection
23–24		Ref.
>24	0.847	(0.721–0.995)	0.043	0.859	(0.731–1.009)	0.065
Clinical treatment modality
Surgery alone		Ref.
Surgery plus postoperative CT or RT/CRT	0.964	(0.889–1.046)	0.379
Surgical techniques			0.502
Two-field		Ref.
Three-field	0.817	(0.572–1.167)	0.266
Unilateral neck and two-field	0.92	(0.629–1.345)	0.665

CRT, chemoradiotherapy; CT, chemotherapy; HR, hazard ratio; MIE, minimally invasive esophagectomy; OE, open esophagectomy; RT, radiotherapy.