Cigarette smoking and mammographic density in the Danish Diet, Cancer and Health cohort

Katja Kemp Jacobsen, Elsebeth Lynge, Ilse Vejborg, Anne Tjønneland, My von Euler-Chelpin, Zorana J. Andersen

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    Purpose Smoking before first childbirth increases breast
    cancer risk, but the biological mechanism remains
    unknown and may involve mammographic density (MD),
    one of the strongest biomarkers of breast cancer risk. We
    aimed to examine whether active smoking and passive
    smoking were associated with MD.
    Methods For the 5,356 women (4,489 postmenopausal)
    from the Danish Diet, Cancer and Health cohort
    (1993–1997) who attended mammographic screening in
    Copenhagen (1993–2001), we used MD (mixed/dense or
    fatty) assessed at the first screening after cohort entry.
    Active smoking (status, duration, and intensity) and passive
    smoking were assessed at cohort baseline (1993–1997) via
    questionnaire, together with other breast cancer risk factors.
    Logistic regression was used to estimate associations
    (odds ratios, 95 % confidence intervals) between smoking
    and MD, adjusting for confounders.
    Results Two thousand and twenty-six (56.5 %) women
    had mixed/dense MD, 2,214 (41.4 %) were current, and
    1,175 (21.9 %) former smokers. Current smokers had
    significantly lower odds (0.86, 0.75–0.99) of having mixed/
    dense MD compared to never smokers, while former
    smoking was not associated with MD. Inverse association
    between smoking and MD was strongest in women who
    initiated smoking before age of 16 years (0.79, 0.64–0.96),
    smoked C15 cigarettes/day (0.83, 0.71–0.98), smoked C5
    pack-years (0.62, 0.43–0.89), smoked [30 years (0.86,
    0.75–0.99), and smoked C11 years before first childbirth
    (0.70, 0.51–0.96). Association between smoking and MD
    diminished after smoking cessation, with increased odds of
    having mixed/dense breasts in women who quit smoking
    [20 years ago as compared to current smokers (1.37,
    1.01–1.67). There was no association between passive
    smoking and MD.
    Conclusions We found an inverse association between
    active smoking and MD.
    TidsskriftCancer Causes & Control
    Udgave nummer2
    Sider (fra-til)271-280
    Antal sider9
    StatusUdgivet - feb. 2016


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