Table 4 Predictive factors for regional lymph node metastasis according to the exploratory logistic regression

Palpable suspicious regional lymph node

No

49

1.0

Reference

Yes

55

8.9

2.7 – 29.2

<0.001

Tumor depth

≤5 mm

20

1.0

Reference

>5 mm

84

11.6

1.4 – 97.1

0.023

Perineural invasion

No

71

1.0

Reference

Yes

33

9.6

2.7 – 33.6

<0.001

SOD2 expression

<50%

57

1.0

Reference

>50%

47

3.4

1.1 – 10.1

0.029