The feasibility analysis of omission of elective irradiation to level IB lymph nodes in low-risk nasopharyngeal carcinoma based on the 2013 updated consensus guideline for neck nodal levels

Table 4 Multivariate analyses of factors on regional recurrence-free survival and overall survival (the whole cohort of patients)

Factor	Regional control				Overall survival
Factor	P value	HR	95% CI		P value	HR	95% CI
Low-risk group
Age (≤ 50y; > 50y)	0.500	0.471	0.053	4.208	0.068	2.394	0.938	6.109
Gender (M/F)	0.760	0.657	0.045	9.654	0.920	0.956	0.392	2.331
T (T1/T2/T3/T4)	0.232	2.262	0.593	8.624	0.131	1.396	0.905	2.153
N (N0/N1/N2/N3)	0.008*	12.076	1.927	75.675	0.925	0.966	0.472	1.980
Nodal necrosis (no/yes)	0.722	0.530	0.016	17.542	0.147	2.155	0.763	6.088
Chemotherapy (no/yes)	0.182	0.101	0.003	2.924	0.528	0.699	0.229	2.128
Elective IB irradiation (no/yes)	0.941	1.122	0.054	23.274	0.799	1.143	0.408	3.206
Boost irradiation of lymph nodes (no/yes)	0.993	0.000	0.000	not reach	0.888	1.162	0.145	9.340
High-risk group
Age (≤ 50y; > 50y)	0.198	1.909	0.714	5.104	0.058	1.798	0.980	3.299
Gender (M/F)	0.682	0.768	0.217	2.715	0.506	0.785	0.385	1.602
T (T1/T2/T3/T4)	0.648	0.879	0.504	1.531	0.285	1.190	0.865	1.637
N (N0/N1/N2/N3)	0.558	1.229	0.617	2.449	0.004*	2.080	1.269	3.411
Nodal necrosis (no/yes)	0.971	1.019	0.365	2.843	0.725	1.130	0.573	2.226
Chemotherapy (no/yes)	0.003*	0.029	0.003	0.299	0.000*	0.034	0.009	0.132
Elective IB irradiation (no/yes)	0.045*	8.540	1.050	69.473	0.243	0.690	0.371	1.285
Boost irradiation of lymph nodes (no/yes)	0.011*	3.793	1.351	10.645	0.906	1.058	0.413	2.710

ISSN: 1748-717X