Table 1 Demographics and univariate survival analysis results of all patients

Gender

 male

1.000

 female

0.774 (0.621,0.964)

  < 55

1.000

  ≥ 55

1.677 (1.338,2.101)

Occupation

 farmer

1.000

 worker

0.788 (0.589,1.056)

 office worker and other

0.724 (0.574,0.913)

Origin

 urban area

1.000

 rural area

1.230 (0.995,1.521)

 Illiteracy

1.000

 Primary-middle school

1.316 (0.826,2.096)

 High school and above

0.663 (0.383,1.147)

TNM classification

 I

1.000

 II

1.395 (0.870,2.234)

 III

2.134 (1.319,3.453)

 IV

2.710 (1.767,4.158)

pT classification

 T₁

1.000

 T₂

1.316 (0.897,1.930)

 T₃

1.734 (1.124,2.676)

 T₄

2.205 (1.531,3.175)

pN classification

 N₀

1.000

 N₁

2.200 (1.638,2.954)

 N₂

3.392 (2.600,4.423)

 N₃

5.016 (2.214,11.367)

 well

1.000

 moderate

1.459 (1.137,1.872)

 poor

1.253 (0.867,1.811)

Adjuvant therapy

 NO

1.000

 RT

0.851 (0.601,1.205)

 CT

1.367 (1.019,1.834)

 CRT

1.144 (0.880,1.488)

Tumor site

 Tongue

1.000

 Gingiva

1.351 (0.981,1.860)

 Floor of mouth

1.404 (0.933,2.114)

 Palate

1.036 (0.675,1.590)

 Buccal

1.148 (0.832,1.585)

 Others

0.798 (0.591,1.077)

Surgery therapy

 No

1.000

 Yes

0.194 (0.152,0.249)