Tilma Vistisen, Helene9; Helene Garde, Anne5; Marie Hansen, Aase6; Hansen, Johnni7; Christiansen, Peer10; Kolstad, Henrik9
1 Department of Clinical Medicine - Occupational Medicine, Department of Clinical Medicine, Health, Aarhus University2 Health, Aarhus University3 Department of Clinical Medicine - The Department of Surgical Gastroenterology L, Department of Clinical Medicine, Health, Aarhus University4 Department of Clinical Medicine, Health, Aarhus University5 National Research Center for the Working Enviroment, Copenhagen, Denmark.6 Institute of Environmental and Occupational Medicine, Faculty of Health Sciences, Aarhus University, Aarhus University7 Danish Cancer Society Research Center, Copenhagen, Denmark.8 Department of Clinical Medicine - Plastikkirurgisk afdeling Z, Department of Clinical Medicine, Health, Aarhus University9 Department of Clinical Medicine - Occupational Medicine, Department of Clinical Medicine, Health, Aarhus University10 Department of Clinical Medicine - Plastikkirurgisk afdeling Z, Department of Clinical Medicine, Health, Aarhus University
OBJECTIVES: Experimental evidence suggest a short-term effect of light at night on breast cancer oncogenesis. We studied the short-term effect of night work on breast cancer occurence. METHOD: We established a large, national cohort of employees in the public health care sector with a high prevalence of night shift work and with detailed data regarding occupational title and date and hour for beginning and end of every work duty: The Danish Working Hour Database (DWHD). DWHD encompasses payroll data as of 2007 and is updated on an annual basis. For this analysis we defined night work as at least 3 h of work between midnight and 05:00. From national cancer registers we retrieved information about breast cancer diagnosis for all female workers and their relatives. Reproductive history, hormone medications, attendance in mammography screening, and vital status were obtained from other national health registries. RESULTS: The 6-year follow up from 2007 to 2012 included 169.011 women of which 98.297 (58%) had ever worked nights during the follow up. A total of1.281 breast cancer cases occurred within the study population. 846 cases occurred among women never worked nights and 435 cases among women ever worked nights. CONCLUSIONS: Internal risk assessment of this dataset that includes alternative exposure metrics based on day-to-day night work exposure information will be presented.
Occupational and Environmental Medicine, 2014, Vol 71 Suppl 1