Table 3.
Associations (multivariablea adjusted incidence RRs) between cigarette smoking and risk of subtypes of head-neck cancer; Netherlands Cohort Study (NLCS), 1986 - 2003
| |
|
Subcohort |
Head-neck cancer cases |
||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| |
|
|
Overall |
Subtypes |
|||||||
| |
|
|
|
OCC
b
|
OHPC
b
|
LC
b
|
|
||||
| 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) | P for 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 | |||||||
aAll analyses were adjusted for age (years), sex, and alcohol consumption (g ethanol/day; continuous).
bOCC: oral cavity cancer; OHPC: oro-/hypopharyngeal cancer; LC: laryngeal cancer.
cTests for dose-response trends were assessed by fitting ordinal variables as continuous terms in the Cox proportional hazards model.
dP Value for interaction between sex and cigarette smoking status, based on cross-product terms in the Cox proportional hazards model and Wald test.
eAdditionally adjusted for frequency (N/day; continuous; centered) and duration of cigarette smoking (years; continuous; centered).
fAnalyses of cigarette smoking frequency were additionally adjusted for current cigarette smoking and duration of cigarette smoking (years; continuous; centered).
gAnalyses of cigarette smoking duration were additionally adjusted for current cigarette smoking and frequency of cigarette smoking (N/day; continuous; centered).
hAnalyses of cigarette smoking pack-years were additionally adjusted for current cigarette smoking.
iCigarette smoking cessation was additionally adjusted for the no. of cigarette pack-years (continuous; centered).
jP < 0.05.
kProportional hazards assumption was possibly violated for the exposure variable, and there was a statistically significant interaction with time.