Table 2 Cox proportional hazard regression analysis of the risk of all-cause death in patients with p16-negative oropharyngeal squamous cell carcinoma receiving concurrent chemoradiotherapy

Pre-CCRT PET–CT (No pre-CCRT PET–CT as reference)

0.95

(0.88–1.03)

0.1986

0.90

(0.82–1.09)

0.4427

Sex

 Female

1

 < 0.0001

1

 < 0.0001

 Male

2.67

(2.19–3.27)

2.41

(1.97–2.95)

Age (years)

 ≤ 40

1

0.0386

1

0.0289

 41–50

1.03

(0.76–1.18)

1.09

(0.76–1.18)

 51–60

1.08

(0.68–1.96)

1.14

(0.70–1.29)

 61–70

1.17

(0.73–1.25)

1.18

(0.70–1.31)

 > 70

1.52

(1.25–1.85)

1.23

(1.00–1.52)

Differentiation

 Well

1

 < 0.0001

 < 0.0001

 Moderate

1.02

(1.00–1.10)

1.04

(1.01–1.32)

 Poor

1.16

(1.07–1.39)

1.17

(1.08–1.41)

AJCC clinical stages

 I–II

1

 < 0.0001

1

 < 0.0001

 III–IVA

1.49

(1.27–1.75)

1.81

(1.53–2.12)

CCI Scores

 0

1

 < 0.0001

1

 < 0.0001

 1

1.14

(1.03–1.27)

1.10

(1.00–1.22)

 2+

1.63

(1.47–1.81)

1.47

(1.32–1.64)

Diagnosis year

 2008–2010

1

0.3212

1

0.1201

 2011–2014

0.96

(0.87–1.06)

0.97

(0.87–1.07)

 2015–2018

0.85

(0.77–1.04)

0.84

(0.73–1.04)

Hospital volume

 High patient volume

1

 < 0.0001

1

 < 0.0001

 Low patient volume

1.23

(1.13–1.33)

1.27

(1.17–1.38)