2.

Predictors from Cox proportional hazard model

Factors	RR	95% CI	P
XRCC1, X-ray cross-complementing gene 1.
Age	1.059	0.859–1.307	0.590
Gender	0.946	0.748–1.196	0.641
Tumor size	1.381	1.116–1.709	0.003
Differentiation	0.909	0.679–1.218	0.523
T category	2.847	1.755–4.620	0.000
N category	1.602	1.447–1.773	0.000
Vascular or nerve invasion	1.366	1.087–1.718	0.008
Adjuvant chemotherapy	0.620	0.492–0.781	0.000
XRCC1	0.862	0.683–1.088	0.347