Department of Community Medicine, Mary Babb Randolph Cancer Center, West Virginia University, Morgantown, WV, USA.
BMJ. 2011 Mar 1;342:d1016. doi: 10.1136/bmj.d1016.
To examine the association between smoking and risk of invasive breast cancer using quantitative measures of lifetime passive and active smoking exposure among postmenopausal women.
Prospective cohort study.
40 clinical centres in the United States.
79,990 women aged 50-79 enrolled in the Women's Health Initiative Observational Study during 1993-8.
Self reported active and passive smoking, pathologically confirmed invasive breast cancer.
In total, 3520 incident cases of invasive breast cancer were identified during an average of 10.3 years of follow-up. Compared with women who had never smoked, breast cancer risk was elevated by 9% among former smokers (hazard ratio 1.09 (95% CI 1.02 to 1.17)) and by 16% among current smokers (hazard ratio 1.16 (1.00 to 1.34)). Significantly higher breast cancer risk was observed in active smokers with high intensity and duration of smoking, as well as with initiation of smoking in the teenage years. The highest breast cancer risk was found among women who had smoked for ≥ 50 years or more (hazard ratio 1.35 (1.03 to 1.77) compared with all lifetime non-smokers, hazard ratio 1.45 (1.06 to 1.98) compared with lifetime non-smokers with no exposure to passive smoking). An increased risk of breast cancer persisted for up to 20 years after smoking cessation. Among women who had never smoked, after adjustment for potential confounders, those with the most extensive exposure to passive smoking (≥ 10 years' exposure in childhood, ≥ 20 years' exposure as an adult at home, and ≥ 10 years' exposure as an adult at work) had a 32% excess risk of breast cancer compared with those who had never been exposed to passive smoking (hazard ratio 1.32 (1.04 to 1.67)). However, there was no significant association in the other groups with lower exposure and no clear dose response to cumulative passive smoking exposure.
Active smoking was associated with an increase in breast cancer risk among postmenopausal women. There was also a suggestion of an association between passive smoking and increased risk of breast cancer.
通过定量评估绝经后女性的终生被动吸烟和主动吸烟暴露情况，研究吸烟与浸润性乳腺癌风险之间的关联。
前瞻性队列研究。
美国 40 个临床中心。
1993 年至 1998 年期间参加妇女健康倡议观察研究的 79990 名年龄在 50-79 岁的女性。
主动和被动吸烟情况，经病理证实的浸润性乳腺癌。
在平均 10.3 年的随访期间，共发现 3520 例浸润性乳腺癌新发病例。与从不吸烟的女性相比，曾经吸烟者乳腺癌风险增加 9%（风险比 1.09（95%可信区间 1.02 至 1.17）），当前吸烟者乳腺癌风险增加 16%（风险比 1.16（1.00 至 1.34））。吸烟强度和持续时间较高，以及青少年时期开始吸烟的活跃吸烟者，乳腺癌风险显著升高。与终生不吸烟者相比，吸烟年限≥50 年或以上的女性乳腺癌风险最高（风险比 1.35（1.03 至 1.77）），与终生不吸烟者且无被动吸烟暴露的女性相比（风险比 1.45（1.06 至 1.98））。吸烟停止后长达 20 年，乳腺癌风险仍持续增加。在从未吸烟的女性中，在校正潜在混杂因素后，与从未接触过被动吸烟的女性相比，暴露于最多被动吸烟的女性（儿童时期暴露≥10 年，成年后在家中暴露≥20 年，成年后在工作中暴露≥10 年）乳腺癌风险增加 32%（风险比 1.32（1.04 至 1.67））。然而，在其他暴露水平较低的组中，没有明显的关联，也没有被动吸烟累积暴露量与风险之间的明确剂量反应关系。
绝经后女性主动吸烟与乳腺癌风险增加相关。此外，被动吸烟与乳腺癌风险增加之间存在关联。
