Table 2 Univariate and multivariate predictors of overall survival

Age (years)

<0.001

<0.001

2.015 (1.789–2.270)

 ≤65

 >65

Gender

0.072

 Male

 Female

Race

<0.001

<0.001

0.911 (0.878–0.945)

 White

 Black

 Indigenous Westerner

 East Asian

 Others

Location

0.532

 Upper

 Middle

 Lower

 Overlapping

Tumor size (cm)

<0.001

<0.001

1.006 (1.004–1.008)

 Diameter ≤1

 1< Diameter ≤2

 2< Diameter ≤3

 3< Diameter ≤4

 4< Diameter ≤5

 Diameter >5

Grade

0.066

 Well differentiated

 Moderately differentiated

 Poorly differentiated

 Undifferentiation

Lymph node-negative group

<0.001

<0.001

0.812 (0.777–0.849)

 LNN 1

 LNN 2

 LNN 3

 LNN 4