Smoking and risk of breast cancer in the Generations Study cohort

Michael E Jones, Minouk J Schoemaker, Lauren B Wright, Alan Ashworth, Anthony J Swerdlow

Research output: Contribution to journalArticlepeer-review


BACKGROUND: Plausible biological reasons exist regarding why smoking could affect breast cancer risk, but epidemiological evidence is inconsistent.

METHODS: We used serial questionnaire information from the Generations Study cohort (United Kingdom) to estimate HRs for breast cancer in relation to smoking adjusted for potentially confounding factors, including alcohol intake.

RESULTS: Among 102,927 women recruited 2003-2013, with an average of 7.7 years of follow-up, 1815 developed invasive breast cancer. The HR (reference group was never smokers) was 1.14 (95% CI 1.03-1.25; P = 0.010) for ever smokers, 1.24 (95% CI 1.08-1.43; P = 0.002) for starting smoking at ages < 17 years, and 1.23 (1.07-1.41; P = 0.004) for starting smoking 1-4 years after menarche. Breast cancer risk was not statistically associated with interval from initiation of smoking to first birth (P-trend = 0.97). Women with a family history of breast cancer (ever smoker vs never smoker HR 1.35; 95% CI 1.12-1.62; P = 0.002) had a significantly larger HR in relation to ever smokers (P for interaction = 0.039) than women without (ever smoker vs never smoker HR 1.07; 95% CI 0.96-1.20; P = 0.22). The interaction was prominent for age at starting smoking (P = 0.003) and starting smoking relative to age at menarche (P = 0.0001).

CONCLUSIONS: Smoking was associated with a modest but significantly increased risk of breast cancer, particularly among women who started smoking at adolescent or peri-menarcheal ages. The relative risk of breast cancer associated with smoking was greater for women with a family history of the disease.

Original languageEnglish
Article number118
Number of pages14
JournalBreast cancer research : BCR
Publication statusPublished - 22 Nov 2017

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© The Author(s). 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
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  • Adult
  • Biomarkers, Tumor
  • Breast Neoplasms/epidemiology
  • Cohort Studies
  • Female
  • History, 21st Century
  • Humans
  • Middle Aged
  • Population Surveillance
  • Risk Assessment
  • Risk Factors
  • Smoking/adverse effects
  • Surveys and Questionnaires
  • United Kingdom/epidemiology

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