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ABSTRACT: Background
The 2014?US Surgeon General's report noted research gaps necessary to determine a causal relationship between active cigarette smoking and invasive breast cancer risk, including the role of alcohol consumption, timing of exposure, modification by menopausal status and heterogeneity by oestrogen receptor (ER) status.Methods
To address these issues, we pooled data from 14 cohort studies contributing 934 681 participants (36 060 invasive breast cancer cases). Cox proportional hazard regression models were used to calculate multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs).Results
Smoking duration before first birth was positively associated with risk ( P -value for trend = 2 × 10 -7 ) with the highest HR for initiation >10 years before first birth (HR?=?1.18, CI 1.12-1.24). Effect modification by current alcohol consumption was evident for the association with smoking duration before first birth ( P -value=2×10 -4 ); compared with never-smoking non-drinkers, initiation >10 years before first birth was associated with risk in every category of alcohol intake, including non-drinkers (HR?=?1.15, CI 1.04-1.28) and those who consumed at least three drinks per day (1.85, 1.55-2.21). Associations with smoking before first birth were limited to risk of ER+ breast cancer ( P -value for homogeneity=3×10 -3 ). Other smoking timing and duration characteristics were associated with risk even after controlling for alcohol, but were not associated with risk in non-drinkers. Effect modification by menopause was not evident.Conclusions
Smoking, particularly if initiated before first birth, was modestly associated with ER+ breast cancer risk that was not confounded by amount of adult alcohol intake. Possible links with breast cancer provide additional motivation for young women to not initiate smoking.
SUBMITTER: Gaudet MM
PROVIDER: S-EPMC5837778 | biostudies-literature | 2017 Jun
REPOSITORIES: biostudies-literature
Gaudet Mia M MM Carter Brian D BD Brinton Louise A LA Falk Roni T RT Gram Inger T IT Luo Juhua J Milne Roger L RL Nyante Sarah J SJ Weiderpass Elisabete E Beane Freeman Laura E LE Sandler Dale P DP Robien Kim K Anderson Kristin E KE Giles Graham G GG Chen Wendy Y WY Feskanich Diane D Braaten Tonje T Isaacs Claudine C Butler Lesley M LM Koh Woon-Puay WP Wolk Alicja A Adami Hans-Olov HO White Emily E Margolis Karen L KL Thun Michael J MJ Gapstur Susan M SM
International journal of epidemiology 20170601 3
<h4>Background</h4>The 2014 US Surgeon General's report noted research gaps necessary to determine a causal relationship between active cigarette smoking and invasive breast cancer risk, including the role of alcohol consumption, timing of exposure, modification by menopausal status and heterogeneity by oestrogen receptor (ER) status.<h4>Methods</h4>To address these issues, we pooled data from 14 cohort studies contributing 934 681 participants (36 060 invasive breast cancer cases). Cox proporti ...[more]