School of Occupational and Public Health, Ryerson University, Toronto ON, Canada.
Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada.
Ann Work Expo Health. 2020 Apr 30;64(4):387-401. doi: 10.1093/annweh/wxaa017.
Shift work with circadian disruption is a suspected human carcinogen. Additional population-representative human studies are needed and large population-based linkage cohorts have been explored as an option for surveillance shift work and cancer risk. This study uses a surveillance linkage cohort and job-exposure matrix to test relationships.
We estimated associations between shift work and breast, ovarian, and prostate cancer using the population-based Canadian Census Health and Environment Cohort (CanCHEC), linking the 1991 Canadian census to national cancer registry and mortality databases. Prevalence estimates from population labour survey data were used to estimate and assign probability of night, rotating, or evening shifts by occupation and industry. Cohort members were assigned to high (>50%), medium (>25 to 50%), low (>5 to 25%), or no (<5%) probability of exposure categories. Cox proportional hazards modelling was used to estimate associations between shift work exposure and incidence of prostate cancer in men and ovarian and breast cancer in women.
The cohort included 1 098 935 men and 939 520 women. Hazard ratios (HRs) indicated null or inverse relationships comparing high probability to no exposure for prostate cancer: HR = 0.96, 95% confidence interval (CI) = 0.91-1.02; breast cancer: HR = 0.94, 95% CI = 0.90-0.99; and ovarian cancer: HR = 0.99, 95% CI = 0.87-1.13.
This study showed inverse and null associations between shift work exposure and incidence of prostate, breast, or ovarian cancer. However, we explore limitations of a surveillance cohort, including a possible healthy worker survivor effect and the possibility that this relationship may require the nuanced exposure detail in primary collection studies to be measurable.
打乱昼夜节律的轮班工作被怀疑是人类的一种致癌因素。需要进行更多具有代表性的人群的医学研究，并且已经探索了基于人群的大型关联队列作为监测轮班工作和癌症风险的一种选择。本研究使用监测关联队列和工作暴露矩阵来检验相关性。
我们使用基于人群的加拿大人口普查健康与环境队列（CanCHEC）来估计轮班工作与乳腺癌、卵巢癌和前列腺癌之间的关系，该队列将 1991 年的加拿大人口普查与国家癌症登记处和死亡率数据库联系起来。使用来自人口劳动力调查数据的流行率估计值来按职业和行业估计和分配夜间、轮班或傍晚班次的概率。将队列成员分配到高（>50%）、中（>25%至 50%）、低（>5%至 25%）或无（<5%）暴露概率类别。使用 Cox 比例风险模型来估计轮班工作暴露与男性前列腺癌、女性卵巢癌和乳腺癌发病率之间的关联。
该队列包括 1098935 名男性和 939520 名女性。危险比（HRs）表明，与高概率暴露相比，高概率暴露与无暴露相比，前列腺癌的风险比（HR）为 0.96，95%置信区间（CI）为 0.91-1.02；乳腺癌：HR = 0.94，95%CI = 0.90-0.99；卵巢癌：HR = 0.99，95%CI = 0.87-1.13。
本研究表明，轮班工作暴露与前列腺癌、乳腺癌或卵巢癌的发病率之间存在反向和零关联。然而，我们探讨了监测队列的局限性，包括可能存在的健康工人幸存者效应，以及这种关系可能需要在原始收集研究中进行细致的暴露细节测量才能测量的可能性。
