PMC:13911 / 5584-8493
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{"target":"https://pubannotation.org/docs/sourcedb/PMC/sourceid/13911","sourcedb":"PMC","sourceid":"13911","source_url":"http://www.ncbi.nlm.nih.gov/pmc/13911","text":"Discussion:\nIn the present study we found a strong inverse relationship \t\t\t\tbetween current smoking and high-risk mammographic parenchymal patterns of \t\t\t\tbreast tissue as classified by Wolfe [12]. These \t\t\t\tfindings are not completely unprecedented; Greendale et al [18] found a reduced risk of breast density in association with \t\t\t\tsmoking, although the magnitude of the reduction was unclear. The present \t\t\t\tfindings suggest that this reduction is large.\nRecent studies [9,10] \t\t\t\thave suggested that breast cancer risk may be reduced among current smokers. In \t\t\t\ta multicentre Italian case-control study, Braga et al [10] found that, relative to nonsmokers, current smokers had a \t\t\t\treduced risk of breast cancer (OR 0.84, 95% CI 0.7-1.0). These findings were \t\t\t\trecently supported by Gammon et al [9], who \t\t\t\treported that breast cancer risk in younger women (younger than 45 years) may \t\t\t\tbe reduced among current smokers who began smoking at an early age (OR 0.59, \t\t\t\t95% CI 0.41-0.85 for age 15 years or younger) and among long-term smokers (OR \t\t\t\t0.70, 95% CI 0.52-0.94 for those who had smoked for 21 years or more).\nThe possible protective effect of smoking might be due to its \t\t\t\tanti-oestrogenic effect [1,2,19]. Recently there has been renewed interest in the potential \t\t\t\teffect of smoking on breast cancer risk, and whether individuals may respond \t\t\t\tdifferently on the basis of differences in metabolism of bioproducts of smoking \t\t\t\t[20,21]. Different relationships \t\t\t\tbetween smoking and breast cancer risk have been suggested that are dependent \t\t\t\ton the rapid or slow status of acetylators of aromatic amines [20,21]. More recent studies [22,23], however, do not support these \t\t\t\tfindings.\nThe present study design minimized the opportunity for bias to \t\t\t\tinfluence the findings. Because subjects were unaware of their own case-control \t\t\t\tstatus, the possibility of recall bias in reporting smoking status was \t\t\t\tminimized. Systematic error in the assessment of mammograms was avoided because \t\t\t\treading was done without knowledge of the risk factor data. Furthermore, the \t\t\t\tassociations observed are unlikely to be explained by the confounding effect of \t\t\t\tother known breast cancer risk factors, because we adjusted for these in the \t\t\t\tanalysis. We did not have information on passive smoking status, however, which \t\t\t\thas recently been reported to be a possible confounder [5,6,21,24].\nThe present data indicate that adjustment for current smoking \t\t\t\tstatus is important when evaluating the relationship between mammographic \t\t\t\tparenchymal pattern and breast cancer risk. They also indicate smoking as a \t\t\t\tprominent potential confounder when analyzing effects of other risk factors \t\t\t\tsuch as obesity-related variables. It seems that parenchymal patterns may act \t\t\t\tas an informative biomarker of the effect of cigarette smoking on breast cancer \t\t\t\trisk.","divisions":[{"label":"Title","span":{"begin":0,"end":11}}],"tracks":[]}