Table 1 Relative risk of breast cancer in relation to current and past smoking duration, intensity and initiation
From: Cigarette smoking and breast cancer risk: a population-based study in Sweden
Smoking measure | Cases/controls | OR a (95% CI) | Cases/controls | OR a (95% CI) |
|---|---|---|---|---|
Never smoker | 1526/1453 | 1.0 (ref) | 1526/1453 | 1.0 (ref) |
Current smokers | Past smokers | |||
Ever smoker | 657/589 | 1.0 (0.9–1.2) | 601/541 | 1.0 (0.9–1.1) |
Duration of smoking, years | ||||
1–10 | 22/28 | 0.7 (0.4–1.3) | 255/216 | 1.0 (0.8–1.3) |
11–30 | 173/147 | 1.0 (0.8–1.3) | 282/257 | 1.0 (0.8–1.2) |
>30 | 457/406 | 1.1 (0.9–1.2) | 61/65 | 0.9 (0.7–1.4) |
P for linear trendb | 0.58 | 0.95 | ||
Cigarettes per day | ||||
1–10 | 282/259 | 1.0 (0.9–1.3) | 373/349 | 1.0 (0.8–1.2) |
11–20 | 347/297 | 1.1 (0.9–1.3) | 196/170 | 1.0 (0.8–1.3) |
>20 | 23/25 | 0.8 (0.4–1.4) | 29/19 | 1.2 (0.7–2.2) |
P for linear trendb | 0.71 | 0.73 | ||
Pack-years | ||||
1–10 | 114/114 | 0.9 (0.7–1.2) | 391/359 | 1.0 (0.8–1.1) |
11–20 | 193/187 | 1.0 (0.8–1.2) | 118/103 | 1.0 (0.8–1.3) |
21–30 | 229/153 | 1.4 (1.1–1.7) | 61/59 | 0.9 (0.6–1.3) |
>30 | 116/127 | 0.9 (0.7–1.2) | 28/17 | 1.5 (0.8–2.8) |
P for linear trendb | 0.77 | 0.69 | ||
Age at initiation, years | ||||
<20 | 359/281 | 1.2 (1.0–1.4) | 300/265 | 1.0 (0.8–1.2) |
20–29 | 196/204 | 0.9 (0.7–1.1) | 221/202 | 1.0 (0.8–1.2) |
⩾30 | 99/99 | 1.0 (0.7–1.3) | 77/71 | 1.1 (0.8–1.5) |
P for linear trendb | 0.73 | 0.99 | ||
Initiation in relation to birth | ||||
Prior | 284/223 | 1.2 (0.9–1.4) | 289/260 | 1.0 (0.8–1.2) |
At around the same time | 196/204 | 1.0 (0.8–1.2) | 157/159 | 1.0 (0.8–1.3) |
Following | 89/99 | 1.0 (0.7–1.4) | 72/63 | 1.3 (0.9–1.9) |
