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J Epidemiol Biostat. 1999;4(4):297-302.

A cohort study of cigarette smoking and risk of fibroadenoma.

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  • 1Department of Public Health Sciences, University of Toronto, Canada.

Abstract

BACKGROUND:

This cohort study examines the association between cigarette smoking and risk of fibroadenoma.

METHODS:

The study was conducted among the 56,537 women in the Canadian National Breast Screening Study (NBSS) who completed self-administered lifestyle and dietary questionnaires. (The NBSS is a randomised, controlled trial of screening for breast cancer in women aged 40-59 at recruitment.) Cases were the 222 women who were diagnosed with biopsy-confirmed incident fibroadenoma. For comparative purposes, a subcohort, consisting of a random sample of 5,681 women was selected from the full dietary cohort. After exclusions for various reasons, the analyses were based on 222 cases and 5,488 non-cases. Incidence rate ratios (IRR) and 95% confidence intervals (CI) were estimated using Poisson regression.

RESULTS:

Cigarette smoking was associated with reduced risk of fibroadenoma, the IRR (95% CI) for more than 550 cigarette-years of exposure being 0.66 (0.40-1.10). Although the reduction in risk was evident for all smokers combined (ex-smokers and current smokers), it was indicative largely of an inverse association in current smokers, in whom the IRR (95% CI) for > 300 cigarette-years of exposure was 0.49 (0.24-0.98). The results were mostly the same when examined in strata defined by method of detection of fibroadenoma, menopausal status and history of previous breast disease. There was no evidence for a reduction in risk with time since last use of cigarettes.

CONCLUSIONS:

The results of this study suggest that cigarette smoking is associated with reduced risk of fibroadenoma, especially in current smokers.

PMID:
10764243
[PubMed - indexed for MEDLINE]
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