Active, but not passive cigarette smoking was inversely associated with mammographic density

Lesley M. Butler, Ellen B Gold, Shannon M. Conroy, Carolyn J. Crandall, Gail A. Greendale, Nina Oestreicher, Charles P. Quesenberry, Laurel A. Habel

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


Purpose The opposing carcinogenic and antiestrogenic properties of tobacco smoke may explain why epidemiologic studies have not consistently reported positive associations for active smoking and breast cancer risk, A negative relation between mammographic density, a strong breast cancer risk factor, and active smoking would lend support for an antiestrogenic mechanism. Methods We used multivariable linear regression to assess the associations of active smoking and secondhand smoke (SHS) exposure with mammographic density in 799 pre- and early perimenopausal women in the Study of Women's Health Across the Nation (SWAN). Results We observed that current active smoking was associated with 7.2% lower mammographic density, compared to never active smoking and no SHS exposure (p = 0.02). Starting to smoke before 18 years of age and having smoked ≥20 cigarettes/day were also associated with statistically significantly lower percent densities. Among nulliparous women having smoked ≥20 cigarettes/ day was associated with 23.8% lower density, compared to having smoked ≤9 cigarettes/day (p < 0.001). Conclusions Our findings support the hypothesis that tobacco smoke exerts an antiestrogenic effect on breast tissue, but counters the known increased risk of breast cancer with smoking prior to first full-term birth. Thus, our data suggest that the antiestrogenic but not the carcinogenic effects of smoking may be reflected by breast density.

Original languageEnglish (US)
Pages (from-to)301-311
Number of pages11
JournalCancer Causes and Control
Issue number2
StatePublished - Feb 2010


  • Breast cancer risk factor
  • Breast density
  • Cigarette smoking
  • Mammographic density
  • Secondhand smoke

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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