Table 4. Comparison of C-index between our modified staging system and the AJCC 8th TNM staging system at 1-, 2-, 3-year in validation cohort.

CSS	Modified			the AJCC 8th		P
	C-index	95% CI		C-index	95% CI
AJCC, American Joint Committee on Cancer; CSS, cancer specific survival; 95% CI, 95% confidence interval.
1-year	0.576	0.520−0.632		0.554	0.497−0.611	0.698
2-year	0.615	0.555−0.674		0.601	0.541−0.660	0.886
3-year	0.815	0.722−0.909		0.742	0.622−0.862	0.005