variable	Treatment modality	RFS	p	DFS	p	OS	p
Stage III-IVa	radiotherapy	66%	0.15	44%	0.04	56%	0.004
Stage III-IVa	Conc-chemoradiotherapy	71%	0.15	58%	0.04	67%	0.004
Positive margin	radiotherapy	72%	0.79	63%	0.034	60%	0.011
Positive margin	Conc-chemoradiotherapy	80%	0.79	75%	0.034	74%	0.011
Perineural invasion	radiotherapy	84%	0.108	58%	0.02	33%	0.03
Perineural invasion	Conc-chemoradiotherapy	85%	0.108	83%	0.02	61%	0.03