Table 2 Univariate and multivariable cox regression analyses of OS in oral cavity squamous cell carcinoma

Age at diagnosis

 18–39

Reference

Reference

 40–49

1.19 (1.05–1.35)

0.007

1.15 (1.01–1.30)

0.034

 50–59

1.43 (1.27–1.61)

< 0.001

1.32 (1.17–1.48)

< 0.001

 60–69

1.83 (1.62–2.06)

< 0.001

1.66 (1.42–1.87)

< 0.001

 70 + 

3.46 (3.07–3.89)

< 0.001

3.21 (2.86–3.62)

< 0.001

Sex

 Female

Reference

Reference

 Male

0.83 (0.80–0.86)

< 0.001

0.94 (0.90–0.97)

< 0.001

Marital status

 Married

Reference

Reference

 Unmarried

1.84 (1.78–1.90)

< 0.001

1.48 (1.43–1.54)

< 0.001

Race

 White

Reference

Reference

 Black

1.82 (1.73–1.92)

< 0.001

1.34 (1.27–1.41)

< 0.001

 Asian or Pacific Islander

0.96 (0.89–1.04)

0.340

1.02 (0.95–1.11)

0.566

 American Indian/Alaska Native

1.08 (0.86–1.36)

0.482

1.04 (0.83–1.31)

0.743

Location

 Floor of mouth

Reference

Reference

 Other mouth

0.62 (0.58–0.66)

< 0.001

0.60 (0.56–0.63)

< 0.001

 Tongue

0.65 (0.62–0.69)

< 0.001

0.71 (0.67–0.76)

< 0.001

Size

 < 1

Reference

Reference

 < 2

1.38 (1.25–1.53)

< 0.001

1.35 (1.22–1.49)

< 0.001

 < 3

1.96 (1.79–2.16)

< 0.001

1.63 (1.45–1.82)

< 0.001

 < 4

2.49 (2.26–2.73)

< 0.001

1.91 (1.69–2.16)

< 0.001

 < 5

3.36 (3.05–3.70)

< 0.001

2.29 (2.02–2.60)

< 0.001

 ≥ 5

5.48 (4.98–6.03)

< 0.001

3.11 (2.74–3.54)

< 0.001

 Unknown

3.17 (2.88–3.50)

< 0.001

2.40 (2.09–2.75)

< 0.001

Treatment

 No/Unknown

Reference

Reference

 Surgery

0.18 (0.18–0.19)

< 0.001

0.30 (0.28–0.32)

< 0.001

 Radiation

0.44 (0.41–0.48)

< 0.001

0.48 (0.44–0.52)

< 0.001

 Chemotherapy + XRT

0.23 (0.22–0.25)

< 0.001

0.26 (0.24–0.27)

< 0.001

 Surgery + XRT

0.21 (0.19–0.22)

< 0.001

0.28 (0.26–0.30)

< 0.001

 Triple therapy

0.18 (0.17–0.19)

< 0.001

0.25 (0.23–0.27)

< 0.001

 Others

0.63 (0.58–0.70)

< 0.001

0.54 (0.49–0.60)

< 0.001

Grade

 Well-differentiated

Reference

Reference

 Moderately differentiated

1.15 (1.09–1.21)

< 0.001

1.07 (1.02–1.13)

0.009

 Poorly differentiated

0.93 (0.88–0.98)

0.006

0.86 (0.81–0.91)

< 0.001

 Undifferentiated

0.83 (0.68–1.02)

0.079

0.78 (0.63–0.95)

0.015

T classification

 T1

Reference

Reference

 T2

1.61 (1.53–1.69)

< 0.001

1.13 (1.04–1.22)

0.004

 T3

2.67 (2.52–2.82)

< 0.001

1.24 (1.13–1.37)

< 0.001

 T4

3.84 (3.66–4.04)

< 0.001

1.89 (1.73–2.06)

< 0.001

 Unknown

1.85 (1.72–1.98)

< 0.001

0.82 (0.73–0.92)

< 0.001

N classification

 N0

Reference

Reference

 N1

1.25 (1.19–1.31)

< 0.001

1.36 (1.29–1.43)

< 0.001

 N2

1.25 (1.20–1.30)

< 0.001

1.38 (1.32–1.45)

< 0.001

 N3

1.71 (1.58–1.86)

< 0.001

1.75 (1.60–1.92)

< 0.001

 Unknown

2.64 (2.33–3.00)

< 0.001

1.44 (1.26–1.65)

< 0.001

M classification

 M0

Reference

Reference

 M1

4.00 (3.72–4.29)

< 0.001

2.54 (2.36–2.74)

< 0.001

 Unknown

2.50 (2.11–2.97)

< 0.001

1.38 (1.16–1.65)

< 0.001