Table 3 Cox regression analysis of risk factors for OS and PFS

Age (> 60 vs. ≤60)

0.99 (0.63–1.56)

0.533

1.16 (0.77–1.74)

0.476

Sex (Male vs. Female)

0.64 (0.28–1.48)

0.935

0.53 (0.24–1.16)

0.111

Smoking (Former/current vs. Never)

0.83 (0.52–1.32)

0.425

0.84 (0.48–1.46)

0.539

Betel nuts (Former/current vs. Never)

1.21 (0.64–2.28)

0.567

0.85 (0.56–1.29)

0.444

Performance status scale (ECOG ≧1 vs. 0)

1.38 (0.87–2.20)

0.176

1.20 (0.78–1.83)

0.414

Primary tumor location (Oral cavity vs. others)

0.77 (0.49–1.21)

0.249

0.80 (0.53–1.21)

0.299

Primary tumor location (Hypolarynx/ larynx vs. others)

1.31 (0.80–2.13)

0.279

1.39 (0.88–2.19)

0.156

 Neoadjuvant chemotherapy (Yes vs. No)

1.18 (0.74–1.88)

0.500

0.94 (0.61–1.43)

0.756

 Primary CCRT (Yes vs. No)

0.93 (0.59–1.47)

0.761

0.83 (0.55–1.25)

0.826

 Adjuvant CCRT (Yes vs. No)

0.88 (0.56–1.39)

0.593

1.07 (0.71–1.60)

0.750

Disease recurrence (Locoregional vs. Distant metastasis)

0.51 (0.32–0.82)

0.005

0.64 (0.40–1.02)

0.060

0.56 (0.37–0.87)

0.009

0.67 (0.43–1.04)

0.075

Salvage surgery (Yes vs. No)

0.21 (0.08–0.58)

0.003

0.24 (0.09–0.69)

0.007

0.30 (0.14–0.70)

0.003

0.34 (0.15–0.77)

0.010

Recurrence after RT (<  6 months vs. >  6 months)

1.44 (0.91–2.30)

0.122

1.35 (0.89–2.06)

0.162