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Table 3 Associations (multivariable a adjusted incidence RRs) between cigarette smoking and risk of subtypes of head-neck cancer; Netherlands Cohort Study (NLCS), 1986 - 2003

From: Alcohol consumption, cigarette smoking and the risk of subtypes of head-neck cancer: results from the Netherlands Cohort Study

   Subcohort Head-neck cancer cases
    Overall Subtypes
     OCCb OHPCb LCb  
  Categorical median Person time at risk (years) No. of cases RR (95% CI) No. of cases RR (95% CI) No. of cases RR (95% CI) No. of cases RR (95% CI) Pfor heterogeneity
Cigarette smoking status            
Never smokers   25051 44 1 (reference) 29 1 (reference) 6 1 (reference) 9 1 (reference) 0.97
Former smokers   22644 110 1.44 (0.97-2.14) 24 0.70 (0.37-1.33) 22 2.68 (1.00-7.14)i 64 2.63 (1.26-5.47)  
Current smokers   16657 241 4.49 (3.11-6.48) 57 2.11 (1.23-3.62) 55 8.53 (3.38-21.55) 126 8.07 (3.94-16.54)  
P for trendc     <0.001   0.001   <0.001   <0.001  
P for interaction with sexd     0.25   0.08   0.44   0.46  
Cigarette smoking status, additionally adjusted for frequency and duration of cigarette smoking e
Never smokers   25051 44 1 (reference) 29 1 (reference) 6 1 (reference) 9 1 (reference) 0.97
Former smokers   22644 110 1.64 (1.08-2.49) 24 0.79 (0.40-1.58) 22 3.03 (1.09-8.45) 64 2.87 (1.34-6.13)  
Current smokers   16657 241 3.51 (2.36-5.23) 57 1.91 (1.06-3.42) 55 7.49 (2.87-19.54) 126 5.26 (2.45-11.28)  
P for trend     <0.001   0.03   <0.001   <0.001  
Frequency of cigarette smoking ( N /day) f
Never smokers 0 25051 44 1 (reference) 29 1 (reference) 6 1 (reference) 9 1 (reference) 0.99
>0 to <20 10 24787 155 1.30 (0.84-2.01) 38 0.63 (0.30-1.32) 30 2.08 (0.73-5.94) 85 2.32 (1.07-5.04)  
≥20 20 14514 196 2.23 (1.45-3.44) 43 1.06 (0.52-2.16) 47 4.67 (1.64-13.34) 105 3.75 (1.73-8.14)  
P for trend     <0.001   0.33   <0.001   <0.001  
Continuous, 10 cigarettes/day increments   64352 395 1.25 (1.13-1.38) 110 1.20 (1.00-1.44)j 83 1.42 (1.20-1.69) 199 1.21 (1.08-1.36) 0.71
Duration of cigarette smoking (years) g
Never smokers 0 25051 44 1 (reference) 29 1 (reference) 6 1 (reference) 9 1 (reference) <0.001
>0 to <20 13 7433 20 1.00 (0.56-1.77) 4 0.38 (0.13-1.17) 5 2.11 (0.59-7.51) 11 1.88 (0.75-4.69)  
20 to <40 30 18999 105 1.44 (0.95-2.21) 30 0.80 (0.41-1.59) 25 2.74 (0.98-7.68) 50 2.35 (1.09-5.06)  
≥40 43 12868 226 2.45 (1.49-4.02) 47 0.98 (0.39-2.46) 47 3.89 (1.22-12.40) 129 4.81 (2.11-11.00)  
P for trend     <0.001   0.87   0.02   <0.001  
Continuous, 10 years increments   64352 395 1.28 (1.14-1.42) 110 1.03 (0.85-1.24) 83 1.36 (1.09-1.70) 199 1.49 (1.25-1.78) 0.25
Pack-years of cigarette smoking h
Never smokers 0 25051 44 1 (reference) 29 1 (reference) 6 1 (reference) 9 1 (reference) 1.00
>0 to <20 9 20832 96 1.16 (0.77-1.76) 24 0.58 (0.30-1.14) 20 2.12 (0.77-5.80) 51 2.07 (0.97-4.41)  
20 to <40 28 12732 132 1.65 (1.04- 2.60) 32 0.84 (0.39-1.83) 26 2.87 (0.94-8.79) 73 2.93 (1.33-6.48)  
≥40 48 5736 123 2.82 (1.76-4.50) 25 1.28 (0.58-2.82) 31 6.49 (2.11-19.95) 66 4.79 (2.15-10.64)  
P for trend     <0.001   0.07   <0.001   <0.001  
Continuous, 10 pack-years increments   64352 395 1.18 (1.11-1.25) 110 1.16 (1.04-1.28) 83 1.24 (1.12-1.36) 199 1.16 (1.09-1.24) 0.77
Cigarette smoking cessation i
Never smokers 25 25051 44 1 (reference) 29 1 (reference) 6 1 (reference) 9 1 (reference) <0.001
Stopped ≥20 years 14 6953 24 1.25 (0.72-2.19) 5 0.63 (0.22-1.81) 6 3.35 (0.97-11.55) 13 1.92 (0.79-4.70)  
Stopped 10 to <20 years 5 7717 36 1.49 (0.91-2.43) 8 0.78 (0.32-1.86) 8 3.29 (1.04-10.39) 20 2.45 (1.07-5.61)k  
Stopped >0 to <10 years 0 7918 50 1.73 (1.09-2.76) 11 0.84 (0.39-1.83) 8 2.48 (0.77-7.93) 31 3.45 (1.56-7.62)  
Current smokers   16657 241 4.26 (2.93-6.20) 57 2.03 (1.16-3.56) 55 8.10 (3.14-20.87) 126 7.53 (3.65-15.51)  
P for trend     <0.001   0.004   <0.001   <0.001  
  1. aAll analyses were adjusted for age (years), sex, and alcohol consumption (g ethanol/day; continuous).
  2. bOCC: oral cavity cancer; OHPC: oro-/hypopharyngeal cancer; LC: laryngeal cancer.
  3. cTests for dose-response trends were assessed by fitting ordinal variables as continuous terms in the Cox proportional hazards model.
  4. d P Value for interaction between sex and cigarette smoking status, based on cross-product terms in the Cox proportional hazards model and Wald test.
  5. eAdditionally adjusted for frequency (N/day; continuous; centered) and duration of cigarette smoking (years; continuous; centered).
  6. fAnalyses of cigarette smoking frequency were additionally adjusted for current cigarette smoking and duration of cigarette smoking (years; continuous; centered).
  7. gAnalyses of cigarette smoking duration were additionally adjusted for current cigarette smoking and frequency of cigarette smoking (N/day; continuous; centered).
  8. hAnalyses of cigarette smoking pack-years were additionally adjusted for current cigarette smoking.
  9. iCigarette smoking cessation was additionally adjusted for the no. of cigarette pack-years (continuous; centered).
  10. j P < 0.05.
  11. kProportional hazards assumption was possibly violated for the exposure variable, and there was a statistically significant interaction with time.