Table 3.
Multivariate-adjusted* hazard ratios (HRs) and 95% confidence intervals (CIs) for the association of smoking characteristics with invasive breast cancer risk by amount of alcohol intake, a pooled analysis among 14 cohorts in the NCI Cohort Consortium
| |
Non-current drinker |
<1 drink per day |
1–2 drinks per day |
≥3 drinks per day |
P-values for interaction | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cases | HR | 95% CI | Cases | HR | 95% CI | Cases | HR | 95% CI | Cases | HR | 95% CI | ||
| Smoking status | |||||||||||||
| Never smoker | 7746 | 1 | 8075 | 1.01 | (0.98, 1.05) | 1110 | 1.06 | (0.99, 1.14) | 303 | 1.21 | (1.06, 1.38) | 0.03 | |
| Former | 2396 | 1.01 | (0.97, 1.06) | 6239 | 1.09 | (1.05, 1.13) | 1415 | 1.25 | (1.18, 1.34) | 528 | 1.33 | (1.19, 1.49) | |
| Current | 1262 | 1.01 | (0.95, 1.08) | 3207 | 1.11 | (1.06, 1.16) | 556 | 1.21 | (1.11, 1.33) | 417 | 1.32 | (1.16, 1.49) | |
| Cigarettes per day in current smokers | |||||||||||||
| Never smoker | 7746 | 1 | 8075 | 1.01 | (0.98, 1.05) | 1110 | 1.06 | (0.99, 1.15) | 303 | 1.2 | (1.04, 1.38) | 0.02 | |
| <10 | 225 | 0.94 | (0.82, 1.07) | 763 | 1.11 | (1.02, 1.20) | 116 | 1.4 | (1.16, 1.69) | 38 | 1.43 | (1.03, 2.00) | |
| 10–19 | 437 | 1.1 | (0.99, 1.21) | 1188 | 1.11 | (1.04, 1.19) | 169 | 1.19 | (1.01, 1.39) | 71 | 1 | (0.78, 1.29) | |
| 20–29 | 366 | 0.95 | (0.86, 1.06) | 815 | 1.07 | (1.00, 1.16) | 166 | 1.18 | (1.01, 1.38) | 147 | 1.3 | (1.08, 1.56) | |
| 30–39 | 139 | 1 | (0.85, 1.18) | 266 | 1.15 | (1.02, 1.31) | 79 | 1.22 | (0.97, 1.53) | 82 | 1.28 | (1.01, 1.62) | |
| ≥40 | 85 | 1.18 | (0.95, 1.47) | 121 | 1.17 | (0.97, 1.40) | 24 | 0.89 | (0.59, 1.33) | 79 | 1.85 | (1.45, 2.36) | |
| P-value for linear trenda | 0.16 | 0.07 | 0.55 | 4×10–3 | |||||||||
| Years of smoking in current smokers | |||||||||||||
| Never smoker | 7746 | 1 | 8075 | 1.01 | (0.98, 1.05) | 1110 | 1.06 | (0.98, 1.14) | 303 | 1.19 | (1.03, 1.37) | 0.03 | |
| <10 | 29 | 1.25 | (0.87, 1.80) | 49 | 0.92 | (0.7, 1.23) | 3 | 0.63 | (0.20, 1.96) | 1 | 0.35 | (0.05, 2.51) | |
| 10–19 | 188 | 1.11 | (0.96, 1.29) | 499 | 1.15 | (1.04, 1.26) | 46 | 1.09 | (0.81, 1.46) | 27 | 1.09 | (0.74, 1.60) | |
| 20–39 | 725 | 0.96 | (0.89, 1.04) | 2097 | 1.11 | (1.05, 1.17) | 338 | 1.15 | (1.03, 1.30) | 282 | 1.31 | (1.13, 1.51) | |
| ≥40 | 294 | 1.07 | (0.95, 1.21) | 545 | 1.07 | (0.97, 1.17) | 146 | 1.45 | (1.23, 1.72) | 99 | 1.42 | (1.13, 1.79) | |
| P-value for linear trenda | 0.25 | 0.12 | 3×10–3 | 7×10–3 | |||||||||
| Years of smoking in former smokers | |||||||||||||
| Never smoker | 7746 | 1 | 8075 | 1.02 | (0.98, 1.05) | 1110 | 1.06 | (0.98, 1.14) | 303 | 1.2 | (1.04, 1.38) | ||
| <5 | 380 | 1 | (0.90, 1.10) | 950 | 1.08 | (1.01, 1.16) | 112 | 1.06 | (0.87, 1.28) | 35 | 1.06 | (0.75, 1.50) | |
| 5–10 | 312 | 1.03 | (0.92, 1.15) | 883 | 1.02 | (0.95, 1.10) | 174 | 1.33 | (1.14, 1.55) | 68 | 1.54 | (1.20, 1.99) | |
| 10–20 | 586 | 0.99 | (0.91, 1.08) | 1876 | 1.13 | (1.07, 1.19) | 388 | 1.34 | (1.20, 1.49) | 153 | 1.35 | (1.13, 1.62) | |
| 20–30 | 444 | 1 | (0.91, 1.10) | 1265 | 1.12 | (1.06, 1.20) | 268 | 1.14 | (1.01, 1.30) | 103 | 1.13 | (0.91, 1.40) | |
| 30–40 | 357 | 1.1 | (0.99, 1.23) | 751 | 1.08 | (1.00, 1.17) | 212 | 1.29 | (1.12, 1.48) | 100 | 1.46 | (1.17, 1.82) | |
| >40 | 124 | 1.1 | (0.92, 1.32) | 214 | 1.08 | (0.94, 1.24) | 80 | 1.59 | (1.27, 1.99) | 44 | 1.59 | (1.16, 2.18) | 2×10–4 |
| P-value for linear trenda | 0.01 | 0.04 | 0.36 | 0.43 | |||||||||
| Years since quitting smoking in former smokers | |||||||||||||
| Never smoker | 7746 | 1 | 8075 | 1.01 | (0.98, 1.05) | 1110 | 1.06 | (0.99, 1.14) | 303 | 1.2 | (1.05, 1.38) | 0.05 | |
| ≥31 | 474 | 1.02 | (0.93, 1.12) | 1209 | 1.05 | (0.98, 1.11) | 276 | 1.22 | (1.08, 1.38) | 95 | 1.19 | (0.95, 1.47) | |
| 21–30 | 634 | 0.97 | (0.89, 1.05) | 1914 | 1.09 | (1.04, 1.15) | 378 | 1.25 | (1.12, 1.39) | 168 | 1.47 | (1.24, 1.74) | |
| 11–20 | 789 | 1.07 | (0.99, 1.15) | 2177 | 1.14 | (1.09, 1.2) | 377 | 1.25 | (1.13, 1.40) | 190 | 1.31 | (1.12, 1.54) | |
| 1–10 | 1262 | 1.01 | (0.95, 1.07) | 3207 | 1.11 | (1.06, 1.16) | 556 | 1.21 | (1.10, 1.32) | 417 | 1.31 | (1.16, 1.48) | |
| P-value for linear trenda | 0.02 | 1×10–3 | 0.48 | 0.95 | |||||||||
| Age of smoking initiation in ever smokers | |||||||||||||
| Never smoker | 7746 | 1 | 8075 | 1.02 | (0.98, 1.05) | 1110 | 1.06 | (0.98, 1.13) | 303 | 1.2 | (1.05, 1.37) | ||
| <16 | 327 | 1.04 | (0.93, 1.16) | 817 | 1.01 | (0.94, 1.09) | 128 | 1.13 | (0.95, 1.35) | 84 | 1.34 | (1.06, 1.69) | |
| 16–20 | 2046 | 1.03 | (0.98, 1.08) | 5576 | 1.08 | (1.04, 1.12) | 1243 | 1.3 | (1.22, 1.39) | 639 | 1.35 | (1.21, 1.50) | |
| 21–25 | 776 | 0.96 | (0.90, 1.04) | 2294 | 1.2 | (1.14, 1.26) | 388 | 1.2 | (1.08, 1.33) | 155 | 1.32 | (1.11, 1.57) | |
| ≥25 | 399 | 1.03 | (0.93, 1.14) | 687 | 1.04 | (0.96, 1.12) | 120 | 1.12 | (0.93, 1.34) | 48 | 1.11 | (0.83, 1.48) | 5×10–6 |
| P-value for linear trenda | 0.79 | 0.75 | 0.04 | 0.13 | |||||||||
| Smoking initiation relative to first birth in parous ever smokers | |||||||||||||
| Never smoker | 6697 | 1 | 7024 | 1.03 | (1.00, 1.07) | 860 | 1.05 | (0.97, 1.14) | 258 | 1.24 | (1.08, 1.43) | 2×10–4 | |
| After first birth | 497 | 1.01 | (0.92, 1.10) | 907 | 1.12 | (1.04, 1.20) | 125 | 1.13 | (0.94, 1.35) | 61 | 1.18 | (0.91, 1.53) | |
| ≤5 years before birth | 1275 | 1 | (0.94, 1.07) | 3195 | 1.09 | (1.05, 1.14) | 591 | 1.24 | (1.14, 1.36) | 314 | 1.35 | (1.18, 1.54) | |
| 6–10 years before birth | 963 | 1.05 | (0.98, 1.12) | 2977 | 1.14 | (1.09, 1.19) | 665 | 1.34 | (1.23, 1.46) | 301 | 1.33 | (1.16, 1.52) | |
| >10 years before birth | 386 | 1.15 | (1.04, 1.28) | 1163 | 1.19 | (1.11, 1.27) | 197 | 1.3 | (1.12, 1.50) | 148 | 1.85 | (1.55, 2.21) | |
| P-value for linear trenda | 0.06 | 6×10–4 | 0.02 | 5×10–4 | |||||||||
*
Multivariable-adjusted models included age, cohort, race/ethnicity, education, birth year, family history of breast cancer, history of benign breast disease, ever use of oral contraceptives, menopausal status and age at menopause, age at menarche, ever use of menopausal hormone therapy, age at first birth and number of live births, body mass index and amount of alcohol use.
a
Linear trend was evaluated using a continuous version of the variable excluding never smokers.