Investigation of the feasibility of elective irradiation to neck level Ib using intensity-modulated radiotherapy for patients with nasopharyngeal carcinoma: a retrospective analysis

Table 5 Multivariate analyses of prognostic factors in low risk patients (n = 904)

Variable	LR-FFS		D-FFS		FFS		OS
Variable	HR (95 % CI)	P ^*	HR (95 % CI)	P ^*	HR (95 % CI)	P ^*	HR (95 % CI)	P ^*
Sex, female vs. male	0.68 (0.34–1.38)	.290	0.82 (0.46–1.42)	.459	0.82 (0.52–1.29)	.384	0.77 (0.37–1.63)	.499
Age, ≥50 vs. <50 years	1.27 (0.69–2.32)	.445	1.44 (0.87–2.37)	.155	1.60 (1.08–2.37)	.020	2.44 (1.29–4.60)	.006
T classification	1.51 (1.11–2.07)	.009	1.32 (1.03–1.70)	.029	1.33 (1.08–1.64)	.007	1.60 (1.12–2.28)	.009
Positive RLNs, (+) vs. (−)	1.70 (0.77–3.73)	.185	1.43 (0.76–2.70)	.266	1.55 (0.94–2.58)	.089	1.17 (0.53–2.57)	.694
Positive CLNs, (+) vs. (−)	2.16 (1.20–3.89)	.010	2.35 (1.40–3.96)	.001	2.01 (1.34–3.04)	.001	2.76 (1.44–5.32)	.002
Positive CLNs at SCF, (+) vs. (−)	1.16 (0.27–5.04)	.846	3.00 (1.24–7.18)	.014	2.12 (0.96–4.71)	.064	2.69 (0.79–9.12)	.113
Chemotherapy, (+) vs. (−)	1.14 (0.38–3.41)	.816	1.18 (0.48–2.91)	.719	0.89 (0.46–1.71)	.717	0.52 (0.20–1.34)	.174
Irradiation of level Ib, (+) vs. (−)	1.68 (0.88–3.19)	.114	1.43 (0.82–2.49)	.207	1.31 (0.83–2.05)	.247	0.88 (0.39–1.95)	.744

Abbreviations: LR-FFS, locoregional failure-free survival; D-FFS, distant failure-free survival; FFS, failure-free survival; OS, overall survival; HR, hazard ratio; 95 % CI, 95 % confidence interval; RLNs, retropharyngeal lymph nodes; CLNs, cervical lymph nodes; D_LN-IIa, greatest dimension of level IIa lymph nodes; LNs, lymph nodes; ES, extra-capsular spread
^*P-values were calculated using an adjusted Cox proportional-hazards model

ISSN: 1471-2407