Table 3. Results of multivariate analysis in different subgroups.

Endpoints	Variable	HR (95% CI)	Pa
Stage III cohort
DFS	N category (N2 vs. N1)	2.030 (1.080–3.815)	0.028
	Treatment group (IC-CCRT vs. CCRT-AC)	0.617 (0.341–1.116)	0.111
OS	KPS (≥ 90 vs. ≤ 80)	0.298 (0.104–0.854)	0.024
	N category (N2 vs. N1)	1.887 (1.045–3.407)	0.035
	Treatment group (IC-CCRT vs. CCRT-AC)	0.704 (0.361–1.373)	0.303
DMFS	N category, N2 vs. N1	2.409 (1.199–4.839)	0.014
	Treatment group (IC-CCRT vs. CCRT-AC)	0.145 (0.043–0.488)	0.002
LRRFS	Treatment group (IC-CCRT vs. CCRT-AC)	1.431 (0.578–3.539)	0.438
Stage IVA cohort
DFS	Smoking (Yes vs. No)	3.239 (1.820–5.763)	< 0.001
	Treatment group (IC-CCRT vs. CCRT-AC)	2.009 (1.316–3.065)	0.001
	N category (N2-3 vs. N0-1)	1.622 (1.083–2.428)	0.019
OS	Smoking (Yes vs. No)	0.254 (0.09–0.714)	< 0.001
	Treatment group (IC-CCRT vs. CCRT-AC)	1.671 (1.060–2.636)	0.027
	N category (N2-3 vs. N0-1)	1.648 (1.062–2.560)	0.026
DMFS	Smoking (Yes vs. No)	2.210 (1.314–3.718)	0.003
	Treatment group (IC-CCRT vs. CCRT-AC)	1.986 (1.155–3.416)	0.013
	N category (N2-3 vs. N0-1)	2.066 (1.209–3.530)	0.008
LRRFS	Treatment group (IC-CCRT vs. CCRT-AC)	1.445 (0.693–3.013)	0.326

Abbreviations: DFS = disease-free survival; OS = overall survival; DMFS = distant metastasis-free survival; LRRFS = locoregional relapse-free survival; HR = hazards ratio; CI = confidence interval; IC = induction chemotherapy; CCRT = concurrent chemoradiotherapy; AC = adjuvant chemotherapy; KPS = karnofsky performance score.

^aMultivariate P-values were calculated using an adjusted Cox proportional-hazards model with backward elimination and the following parameters: age (> 48 y vs. ≤ 48 y), gender (female vs. male), KPS (≥ 90 vs. ≤ 80), smoking (yes vs. no), drinking (yes vs. no), T category (T3-4 vs. T1-2), N category (N2-3 vs. N0-1), concurrent chemotherapy regimen (TP vs. PF) and treatment group (IC-CCRT vs. CCRT-AC).