Table 3 Univariate and multivariate predictors of overall survival (data late than 2004)

Age (years)

<0.001

<0.001

2.194 (1.529–3.148)

 ≤65

 >65

Gender

0.404

 Male

 Female

Race

0.01

0.724

0.981 (0.881–1.092)

 White

 Black

 Indigenous Westerner

 East Asian

 Others

Location

0.74

 Upper

 Middle

 Lower

 Overlapping

Tumor size (cm)

<0.001

0.896

1.000 (0.994–1.007)

 Diameter ≤1

 1< Diameter ≤2

 2< Diameter ≤3

 3< Diameter ≤4

 4< Diameter ≤5

 Diameter >5

Depth of invasion

<0.001

<0.001

1.684 (1.463–1.937)

 T0 and T1

 T2

 T3

 T4

Grade

0.654

 Well differentiated

 Moderately differentiated

 Poorly differentiated

 Undifferentiation

Lymph node-negative group

0.006

<0.001

0.773 (0.674–0.886)

 LNN 1

 LNN 2

 LNN 3

 LNN 4