Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, California, USA.
School of Community and Global Health, Claremont Graduate University, Claremont, California, USA.
Chronobiol Int. 2021 Aug;38(8):1151-1161. doi: 10.1080/07420528.2021.1912073. Epub 2021 Apr 27.
Working at night causes circadian disruption and it has been classified as a probable carcinogen. An evening chronotype, or preference for late day activity, has been shown to increase risk for several adverse health effects, such as metabolic disorders and recently, breast cancer. To further explore this emerging area of interest, we examined the association between endometrial cancer (EC) risk, another common cancer in women, and chronotype. The women in this study were members of the California Teachers Study cohort, which was established in 1995. Chronotype was reported on a subsequent questionnaire (Q5), administered in 2012-2013. The women included in this analysis were under age 90 years, were post-menopausal at Q5, and had no hysterectomy. The cancer cases, identified through linkages to the California Cancer Registry, were diagnosed between 1996 and 2014. We used unconditional logistic regression models to estimate the odds ratios (ORs) and 95% confidence intervals (CIs) of the associations between chronotype and EC diagnosis. There were 437 EC cases and 26,753 cancer-free controls included in this analysis. Controls were more likely to classify themselves as current morning chronotypes than were cases (39% and 34%, respectively). Compared to morning types, women who were definite evening types had a statistically significantly elevated OR of 1.44 (95% CI 1.09-1.91). This association was more pronounced among obese women as compared to non-obese women. For evening type compared to morning type, the OR among obese women was 2.01 (95% CI 1.23, 3.29) while the OR for non-obese women was 1.12 (95% CI 0.77, 1.63). To our knowledge, the association between EC risk and evening chronotype has not been previously reported, but is consistent with the small body of literature which suggests increased breast cancer risks among evening chronotypes. Because this study was based on a retrospective analysis in a cohort of mostly white female teachers in California, further analysis of chronotype as a potential EC risk factor should be considered in other cohorts and in prospective analyses in order to further explore this relationship.
夜间工作会导致生物钟紊乱，并且已被归类为可能的致癌物质。夜间型或喜欢晚些时候活动的人，已被证明会增加几种不良健康影响的风险，例如代谢紊乱，最近还会增加乳腺癌的风险。为了进一步探索这一新兴研究领域，我们研究了子宫内膜癌（EC）风险与生物钟之间的关系，EC 是女性中另一种常见的癌症。本研究中的女性是加利福尼亚教师研究队列的成员，该队列成立于 1995 年。随后在 2012-2013 年进行的问卷（Q5）中报告了生物钟类型。在此分析中包括的女性年龄在 90 岁以下，在 Q5 时已绝经，并且没有子宫切除术。通过与加利福尼亚癌症登记处的链接确定癌症病例，这些病例的诊断时间在 1996 年至 2014 年之间。我们使用无条件逻辑回归模型来估算生物钟类型与 EC 诊断之间的关联的优势比（OR）和 95％置信区间（CI）。在这项分析中，有 437 例 EC 病例和 26,753 例无癌症对照。与病例相比，对照更有可能将自己归类为当前的晨型（分别为 39％和 34％）。与晨型相比，明确的夜间型女性发生 EC 的风险比（OR）统计学上显著升高 1.44（95％CI 1.09-1.91）。与非肥胖女性相比，这种关联在肥胖女性中更为明显。与晨型相比，肥胖女性的夜间型 OR 为 2.01（95％CI 1.23，3.29），而非肥胖女性的 OR 为 1.12（95％CI 0.77，1.63）。据我们所知，以前尚未报道过 EC 风险与夜间生物钟之间的关联，但与表明夜间型的乳腺癌风险增加的少量文献一致。由于这项研究是基于加利福尼亚州主要为白人女教师的队列中的回顾性分析，因此应在其他队列和前瞻性分析中进一步考虑生物钟作为潜在的 EC 风险因素，以进一步探索这种关系。
