Title |
Night shift work and breast cancer: a pooled analysis of population-based case–control studies with complete work history
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Published in |
European Journal of Epidemiology, February 2018
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DOI | 10.1007/s10654-018-0368-x |
Pubmed ID | |
Authors |
Emilie Cordina-Duverger, Florence Menegaux, Alexandru Popa, Sylvia Rabstein, Volker Harth, Beate Pesch, Thomas Brüning, Lin Fritschi, Deborah C. Glass, Jane S. Heyworth, Thomas C. Erren, Gemma Castaño-Vinyals, Kyriaki Papantoniou, Ana Espinosa, Manolis Kogevinas, Anne Grundy, John J. Spinelli, Kristan J. Aronson, Pascal Guénel |
Abstract |
Night shift work has been suspected to increase breast cancer risk but epidemiological studies have been inconsistent due to heterogeneous assessment of exposure to night work. To overcome this limitation, we pooled data of five population-based case-control studies from Australia, Canada, France, Germany, and Spain into a single harmonized dataset using a common definition of night work including 6093 breast cancer cases and 6933 population controls. The odds ratio for breast cancer in women who ever worked at night for at least 3 h between midnight and 5 a.m. as compared to never night workers was 1.12 (95% CI 1.00-1.25). Among pre-menopausal women, this odds ratio was 1.26 [1.06-1.51], increasing to 1.36 [1.07-1.74] for night shifts ≥ 10 h, 1.80 [1.20-2.71] for work ≥ 3 nights/week, and 2.55 [1.03-6.30] for both duration of night work ≥ 10 years and exposure intensity ≥ 3 nights/week. Breast cancer risk in pre-menopausal women was higher in current or recent night workers (OR = 1.41 [1.06-1.88]) than in those who had stopped night work more than 2 years ago. Breast cancer in post-menopausal women was not associated with night work whatever the exposure metric. The increase in risk was restricted to ER+ tumors, particularly those who were both ER+ and HER2+ . These results support the hypothesis that night shift work increases the risk of breast cancer in pre-menopausal women, particularly those with high intensity and long duration of exposure. Risk difference between pre- and post-menopausal women deserves further scrutiny. |
X Demographics
Geographical breakdown
Country | Count | As % |
---|---|---|
Finland | 10 | 24% |
Canada | 3 | 7% |
United Kingdom | 2 | 5% |
United States | 2 | 5% |
Spain | 1 | 2% |
France | 1 | 2% |
India | 1 | 2% |
Unknown | 21 | 51% |
Demographic breakdown
Type | Count | As % |
---|---|---|
Members of the public | 34 | 83% |
Practitioners (doctors, other healthcare professionals) | 4 | 10% |
Scientists | 3 | 7% |
Mendeley readers
Geographical breakdown
Country | Count | As % |
---|---|---|
Unknown | 124 | 100% |
Demographic breakdown
Readers by professional status | Count | As % |
---|---|---|
Student > Bachelor | 19 | 15% |
Student > Ph. D. Student | 16 | 13% |
Student > Master | 16 | 13% |
Researcher | 10 | 8% |
Student > Doctoral Student | 5 | 4% |
Other | 21 | 17% |
Unknown | 37 | 30% |
Readers by discipline | Count | As % |
---|---|---|
Medicine and Dentistry | 21 | 17% |
Biochemistry, Genetics and Molecular Biology | 12 | 10% |
Nursing and Health Professions | 8 | 6% |
Agricultural and Biological Sciences | 8 | 6% |
Neuroscience | 5 | 4% |
Other | 28 | 23% |
Unknown | 42 | 34% |