Table 4 Cox regression analysis evaluating the value of surgical margins and perineural invasion as a predictor of time to biochemical recurrence in a subgroup analysis regarding pathological tumor stage

Surgical margins

< 0.001

0.002

< 0.001

0.011

 NSM

1.0 (Ref.)

1.0 (Ref.)

1.0 (Ref.)

1.0 (Ref.)

 AM

4.8 (2.1–11.2)

< 0.001

4.9 (2.1–11.8)

< 0.001

2.3 (0.8–6.5)

0.122

3.7 (1.2–11.1)

0.019

 OM

2.1 (0.5–9.1)

0.343

2.6 (0.6–11.5)

0.216

2.6 (1.3–5.3)

0.007

1.3 (0.6–2.6)

0.51

 MM

6.5 (3.0–14.5)

< 0.001

3.1 (1.3–7.5)

0.014

4.5 (2.2–9.2)

< 0.001

2.8 (1.4–5.9)

0.005

 No

1.0 (Ref.)

1.0 (Ref.)

1.0 (Ref.)

 Yes

2.4 (1.2–4.6)

0.01

0.9 (0.4–2.0)

0.808

1.7 (1.0–2.9)

0.044

1.5 (0.9–2.6)

0.157