Almost 15 million Americans regularly work alternate shifts, including evening, night, and rotating shifts. Shift work is integral to the modern work force, which spans all age and ethnic groups. Observational studies have consistently associated rotating shift work with increases in cancer risk, prompting the WHO in December 2007 to classify night shift work a probable carcinogen - the main operating mechanism being assumed circadian disruption by means of melatonin suppression. Based on results from the Nurses'Health Study II (NHS2), in March 2009, Denmark as the first country worldwide began paying monetary compensation to women who developed breast cancer after 20 or more years of night shift work. Because no definitive strategy currently exists to reduce the cancer risk associated with shift work-induced circadian disruption, determining what aspects of shift schedules are most detrimental to health is the next frontier in shift work and disease prevention. To date, no study has examined how specific aspects of shift schedules including length, frequency of rotation, and hours worked per week interact and relate to cancer risk. Moreover, whether there is an age range at which people are particularly vulnerable to the effects of circadian disruption also remains unclear. Future research would benefit from a clear and complete description of work schedules and their effects on human cancer risk. In 2009, we have added a battery of shift work questions to the main NHS2 questionnaire. We newly assess specific aspects of the nurses'work schedule including types of shift schedules and changes throughout their professional career. In addition, other factors of potential relevance to circadian disruption were assessed, including morningness-eveningness and sleep duration during each of the various life time periods. To evaluate the hypothesis that certain aspects of shift work schedules are more strongly associated with breast cancer risk than others, we will use both a cohort and cross-sectional study approach. We estimate 1,108 newly diagnosed cases of breast cancer between 2009 and 2013. We will use these cases, as well as prevalent cases to enhance the power of subanalyses, for an estimated total of 4,295 women with a diagnosis of breast cancer through 2013. Because mechanisms that link shift work to breast cancer risk are similar for other cancers, the findings from this proposal are likely to affect not only the risk of breast cancer but that of other cancers and men as well. We expect that the impact of our results will extend well beyond the specific aims we currently propose. Ultimately, as time progresses and nurses become older, this data and the newly added battery of shift work questions will lay the foundation for a comprehensive and unique study of shift work on the health needs of older workers.

Public Health Relevance

In December 2007, the WHO classified night shift work as probably inducing cancer - the main operating mechanism being assumed the suppression of melatonin and consequences thereof. Because no definitive strategy currently exists to reduce the cancer risk associated with shift work- induced changes in the body that could lead to cancer risk, determining what specific aspects of the nurses'work schedule including types of shift schedules and changes throughout their professional career are most detrimental to cancer risk is the next frontier in shift work and disease prevention. PROJECT NARRATIVE In December 2007, the WHO classified night shift work as probably inducing cancer - the main operating mechanism being assumed the suppression of melatonin and consequences thereof. Because no definitive strategy currently exists to reduce the cancer risk associated with shift work- induced changes in the body that could lead to cancer risk, determining what specific aspects of the nurses'work schedule including types of shift schedules and changes throughout their professional career are most detrimental to cancer risk is the next frontier in shift work and disease prevention.

Agency
National Institute of Health (NIH)
Institute
National Institute for Occupational Safety and Health (NIOSH)
Type
Research Project (R01)
Project #
5R01OH009803-05
Application #
8706120
Study Section
Safety and Occupational Health Study Section (SOH)
Program Officer
Childress, Adele M
Project Start
2010-08-01
Project End
2015-07-31
Budget Start
2014-08-01
Budget End
2015-07-31
Support Year
5
Fiscal Year
2014
Total Cost
Indirect Cost
Name
Brigham and Women's Hospital
Department
Type
DUNS #
City
Boston
State
MA
Country
United States
Zip Code
02115
Wegrzyn, Lani R; Tamimi, Rulla M; Rosner, Bernard A et al. (2017) Rotating Night-Shift Work and the Risk of Breast Cancer in the Nurses' Health Studies. Am J Epidemiol 186:532-540
Devore, Elizabeth E; Massa, Jennifer; Papantoniou, Kyriaki et al. (2017) Rotating night shift work, sleep, and colorectal adenoma in women. Int J Colorectal Dis 32:1013-1018
Heckman, Carolyn J; Kloss, Jacqueline D; Feskanich, Diane et al. (2017) Associations among rotating night shift work, sleep and skin cancer in Nurses' Health Study II participants. Occup Environ Med 74:169-175
Devore, Elizabeth E; Warner, Erica T; Eliassen, A Heather et al. (2017) Urinary Melatonin in Relation to Postmenopausal Breast Cancer Risk According to Melatonin 1 Receptor Status. Cancer Epidemiol Biomarkers Prev 26:413-419
Schernhammer, Eva S (2017) RE: Night Shift Work and Breast Cancer Incidence: Three Prospective Studies and Meta-analysis of Published Studies. J Natl Cancer Inst 109:
Vetter, Céline; Devore, Elizabeth E; Wegrzyn, Lani R et al. (2016) Association Between Rotating Night Shift Work and Risk of Coronary Heart Disease Among Women. JAMA 315:1726-34
Hersh, Caleb; Sisti, Julia; Richiutti, Vincent et al. (2015) The effects of sleep and light at night on melatonin in adolescents. Hormones (Athens) 14:399-409
Ramin, Cody A; Massa, Jennifer; Wegrzyn, Lani R et al. (2015) The association of body size in early to mid-life with adult urinary 6-sulfatoxymelatonin levels among night shift health care workers. BMC Public Health 15:467
Ramin, Cody; Devore, Elizabeth E; Wang, Weike et al. (2015) Night shift work at specific age ranges and chronic disease risk factors. Occup Environ Med 72:100-7
Vetter, Céline; Devore, Elizabeth E; Ramin, Cody A et al. (2015) Mismatch of Sleep and Work Timing and Risk of Type 2 Diabetes. Diabetes Care 38:1707-13

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