Minimizing Cancer Risk in Shift Workers

描述（由申请人提供）：近1500万美国人经常轮班工作，包括夜班、夜班和轮班。轮班工作是现代劳动力不可或缺的一部分，它涵盖了所有年龄和种族。观察性研究一直将轮班工作与癌症风险的增加联系起来，促使世界卫生组织在2007年12月将夜班工作列为可能的致癌物——其主要运作机制被认为是通过抑制褪黑激素来扰乱昼夜节律。根据护士健康研究II （NHS2）的结果，2009年3月，丹麦成为世界上第一个开始向夜班工作20年以上的患乳腺癌的妇女支付金钱补偿的国家。由于目前还没有明确的策略来降低与倒班工作引起的昼夜节律紊乱相关的癌症风险，因此确定倒班时间表的哪些方面对健康最有害是倒班工作和疾病预防的下一个前沿。到目前为止，还没有研究调查轮班安排的具体方面，包括轮班的长度、频率和每周工作时间，是如何相互作用和与癌症风险相关的。此外，是否存在一个年龄段的人特别容易受到昼夜节律紊乱的影响也尚不清楚。未来的研究将受益于对工作时间表及其对人类癌症风险的影响的清晰和完整的描述。2009年，我们在NHS2的主要问卷中增加了一系列轮班工作的问题。我们最新评估护士工作时间表的具体方面，包括轮班时间表的类型和整个职业生涯的变化。此外，还评估了与昼夜节律中断潜在相关的其他因素，包括每个不同生命时期的早晚性和睡眠持续时间。为了评估轮班工作时间表的某些方面与乳腺癌风险的关系比其他方面更强的假设，我们将使用队列和横断面研究方法。我们估计2009年至2013年期间有1108例新诊断的乳腺癌病例。我们将使用这些病例以及流行病例来增强亚分析的力量，到2013年，估计总共有4295名诊断为乳腺癌的妇女。由于倒班工作与乳腺癌风险之间的联系机制与其他癌症相似，因此这项研究的结果可能不仅会影响乳腺癌的风险，还会影响其他癌症和男性的风险。我们期望我们的成果的影响将远远超出我们目前提出的具体目标。最终，随着时间的推移和护士年龄的增长，这些数据和新增加的轮班工作问题将为全面而独特的轮班工作对老年工作者健康需求的研究奠定基础。

DESCRIPTION (provided by applicant): 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.