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Author (up) Hansen, J.; Lassen, C.F.
Title Nested case-control study of night shift work and breast cancer risk among women in the Danish military Type Journal Article
Year 2012 Publication Occupational and Environmental Medicine Abbreviated Journal Occup Environ Med
Volume 69 Issue 8 Pages 551-556
Keywords Adult; Aged; Aged, 80 and over; Breast Neoplasms/*etiology; Case-Control Studies; *Circadian Rhythm; Denmark/epidemiology; Female; Humans; Logistic Models; Middle Aged; Military Personnel; *Occupations; Odds Ratio; Risk Factors; *Sunlight; *Work; *Work Schedule Tolerance; oncogenesis
Abstract OBJECTIVES: Growing but limited evidence suggests that night shift work is associated with breast cancer. The authors conducted a nationwide case-control study nested within a cohort of 18,551 female military employees born in 1929-1968 to investigate the risk for breast cancer after night shift work and to explore the role of leisure time sun exposure and diurnal preference. METHODS: The authors documented 218 cases of breast cancer (1990-2003) and selected 899 age-matched controls from the cohort by incidence density sampling. Information on shift work, sun exposure habits, diurnal preference and other potential confounders was obtained from a structured questionnaire. ORs were estimated by multivariate conditional logistic regression. RESULTS: Overall, the authors observed an adjusted OR of 1.4 (95% CI 0.9 to 2.1) among women with ever compared with never night shifts. The RR for breast cancer tended to increase with increasing number of years of night shift work (p=0.03) and with cumulative number of shifts (p=0.02),with a neutral risk for fewer than three night shifts per week. The OR for the group with the highest tertile of cumulative exposure was 2.3 (95% CI 1.2 to 4.6). The most pronounced effect of night shift work on breast cancer risk was observed in women with morning chronotype preference and intense night shifts (OR=3.9, 95% CI 1.6 to 9.5). Night shift workers tended to sunbathe more frequently than day workers. CONCLUSIONS: The results indicate that frequent night shift work increases the risk for breast cancer and suggest a higher risk with longer duration of intense night shifts. Women with morning preference who worked on night shifts tended to have a higher risk than those with evening preference.
Address Institute of Cancer Epidemiology, Danish Cancer Society, Strandboulevarden 49, Copenhagen DK2100, Denmark. johnni@cancer.dk
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1351-0711 ISBN Medium
Area Expedition Conference
Notes PMID:22645325 Approved no
Call Number IDA @ john @ Serial 156
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