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Eur J Epidemiol. 2017 Aug;32(8):683-690. doi: 10.1007/s10654-017-0282-7. Epub 2017 Jul 14.

A possible dual effect of cigarette smoking on the risk of postmenopausal breast cancer.

Author information

1
Department of Epidemiology, GROW- School for Oncology and Developmental Biology, Maastricht University Medical Centre, PO Box 616, 6200, MD, Maastricht, The Netherlands. PA.vandenBrandt@maastrichtuniversity.nl.
2
Department of Epidemiology, CAPHRI- School for Public Health and Primary Care, Maastricht University Medical Centre, Maastricht, The Netherlands. PA.vandenBrandt@maastrichtuniversity.nl.

Abstract

Smoking seems modestly associated with breast cancer, but the potential dual effect of smoking (with opposing properties: carcinogenic vs anti-estrogenic) is understudied. The relationship between smoking before and after menopause and risk of postmenopausal breast cancer was investigated in the Netherlands Cohort Study (NLCS). In the NLCS, 62,573 women aged 55-69 years provided information on smoking, dietary and other lifestyle habits in 1986. Follow-up for cancer incidence until 2007 (20.3 years) consisted of record linkages with the Netherlands Cancer Registry and the Dutch Pathology Registry PALGA. Multivariate case-cohort analyses were based on 2526 incident breast cancer cases and 1816 subcohort members with complete data on smoking. When smoking during pre- and postmenopausal periods was mutually adjusted for, breast cancer risk was significantly positively associated with premenopausal smoking pack-years, but inversely associated with postmenopausal smoking pack-years, both in a dose-dependent manner. In continuous analyses, the hazard ratios (95% CI) were 1.35 (1.10-1.65), and 0.47 (0.28-0.80) per increment of 20 premenopausal, and postmenopausal pack-years, respectively. The interaction between pre- and postmenopausal pack-years in relation to breast cancer risk was significant (P < 0.001). This study highlights the importance of distinguishing and adjusting for smoking in different life periods, and suggests dual effects of smoking on postmenopausal breast cancer risk.

KEYWORDS:

Breast cancer; Cohort study; Menopause; Smoking

PMID:
28710542
PMCID:
PMC5591344
DOI:
10.1007/s10654-017-0282-7
[Indexed for MEDLINE]
Free PMC Article

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