Night Shift Work Increases the Risks of Multiple Primary Cancers in Women: A Systematic Review and Meta-analysis of 61 Articles

Disruption of Circadian Clock Induces Abnormal Mammary Morphology and Aggressive Basal Tumorigenesis by Enhancing LILRB4 Signaling

Epidemiological studies have shown that circadian rhythm disruption (CRD) is associated with the risk of breast cancer. However, the role of CRD in mammary gland morphology and aggressive basal mammary tumorigenesis and the molecular mechanisms underlying CRD and cancer risk remain unknown. To investigate the effect of CRD on aggressive tumorigenesis, a genetically engineered mouse model that recapitulates the human basal type of breast cancer was used for this study. The effect of CRD on mammary gland morphology was investigated using wild-type mice model. The impact of CRD on the tumor microenvironment was investigated using the tumors from LD12:12 and CRD mice via scRNA seq. ScRNA seq was substantiated by multiplexing immunostaining, flow cytometry, and realtime PCR. The effect of LILRB4 immunotherapy on CRD-induced tumorigenesis was also investigated. Here we identified the impact of CRD on basal tumorigenesis and mammary gland morphology and identified the role of LILRB4 on CRD-induced lung metastasis. We found that chronic CRD disrupted mouse mammary gland morphology and increased tumor burden, and lung metastasis and induced an immunosuppressive tumor microenvironment by enhancing LILRB4a expression. Moreover, CRD increased the M2-macrophage and regulatory T-cell populations but decreased the M1-macrophage, and dendritic cell populations. Furthermore, targeted immunotherapy against LILRB4 reduced CRD-induced immunosuppressive microenvironment and lung metastasis. These findings identify and implicate LILRB4a as a link between CRD and aggressive mammary tumorigenesis. This study also establishes the potential role of the targeted LILRB4a immunotherapy as an inhibitor of CRD-induced lung metastasis.

Evaluation of the Impact of Night Shift Work on Disease Severity in Psoriatic Patients: A Case-Control Study with Clinical, Hormonal, and Immunological Evaluation

INTRODUCTION

Night shift work disrupts circadian rhythms and has been associated with immune system alterations and various health conditions. However, there is limited data regarding its impact on psoriasis. The aim of our study was to compare psoriasis severity and the hormonal and immunological profile in patients with a night shift work to those with a daytime occupation.

METHODS

In this case-control study, we enrolled psoriatic patients aged >18 years engaged in night shift work and a control group of psoriatic patients with a daytime occupation. A further categorization was performed by the duration of night shift work: < or ≥7 days a month and < or ≥8 years. Disease severity was evaluated by PASI, BSA, and DLQI, and blood samples were taken to measure various hormonal and immunological markers. Univariable and multivariable analysis were performed to assess differences between the two groups.

RESULTS

A total of 40 night shift workers were included, along with 36 patients in the control group. Patients who worked night shifts at least 7 days a month had significantly higher PASI scores (11.2 ± 6.6 vs. 8.5 ± 6.6; p = 0.04) and higher IL-8 serum (115.33 ± 463.65 pg/mL vs. 19.98 ± 29.78 pg/mL; p = 0.006) compared to patients who did not. Night shifts workers for at least 8 years had higher BMI (28.65 ± 4.56 vs. 25.32 ± 5.50, p = 0.010), and females had higher testosterone levels (0.46 ± 0.53 ng/mL vs. 0.23 ± 0.13 ng/mL; p = 0.055).

CONCLUSION

Night shift might increase psoriasis severity and have an impact on chronic inflammation, obesity, and hormonal imbalances.

Cell state dependent effects of Bmal1 on melanoma immunity and tumorigenicity

The circadian clock regulator Bmal1 modulates tumorigenesis, but its reported effects are inconsistent. Here, we show that Bmal1 has a context-dependent role in mouse melanoma tumor growth. Loss of Bmal1 in YUMM2.1 or B16-F10 melanoma cells eliminates clock function and diminishes hypoxic gene expression and tumorigenesis, which could be rescued by ectopic expression of HIF1α in YUMM2.1 cells. By contrast, over-expressed wild-type or a transcriptionally inactive mutant Bmal1 non-canonically sequester myosin heavy chain 9 (Myh9) to increase MRTF-SRF activity and AP-1 transcriptional signature, and shift YUMM2.1 cells from a Sox10high to a Sox9high immune resistant, mesenchymal cell state that is found in human melanomas. Our work describes a link between Bmal1, Myh9, mouse melanoma cell plasticity, and tumor immunity. This connection may underlie cancer therapeutic resistance and underpin the link between the circadian clock, MRTF-SRF and the cytoskeleton.

Consequences of Shift Work and Night Work: A Literature Review

Nonstandard work schedules such as shift work and night work tend to trigger problems for workers in different areas. To illustrate the diversity of areas affected and the relative interest of the scientific community, we conducted a literature review of the effects of shift work and night work on workers. In particular, we intended to identify the main variables addressed in the field of health, the family sphere, and the organizational context. The literature review was carried out using the Web of Science with the following terms: "shift work", "rotating shifts", and "night work". Inclusion criteria incorporated empirical studies and articles written in Portuguese or English published in 2019. We selected 129 of the 619 articles identified. Regarding the impacts of shift work and night work, there existed a high discrepancy of focus between the three defined areas: health, family life, and organizational context. Specifically, health-related variables were the most studied (83.4%), followed by organizational variables (9.2%), and, lastly, family variables (7.4%). Based on these results, it is essential to extend the study of the two underrepresented impacts to other crucial areas, not only for the worker but also for organizations.

Association between Breast Cancer and Second Primary Lung Cancer among the Female Population in Taiwan: A Nationwide Population-Based Cohort Study

PURPOSE

A special association between breast cancer and second primary lung cancer in Taiwanese women has been discovered not only in clinical practice, but also in a large population-based study. We hereby investigate the association between breast cancer and second primary lung cancer in Taiwanese women.

METHODS

This study was conducted from the National Health Insurance Research Database (NHIRD) from Taiwan National Health Insurance (NHI). Patients older than 18 years old and hospitalized with a first diagnosis of breast cancer during 2000 to 2012 were enrolled in the breast cancer group. Patients who were cancer free were frequency-matched with the breast cancer group by age (every five-year span) and index year. The ratio of breast cancer group to non-breast cancer group was 1:4. The event as the outcome in this study was lung cancer. The comorbidities viewed as important confounding factors included coronary artery disease, stroke, hypertension, diabetes, chronic obstructive pulmonary disease, hyperlipidemia, tuberculosis, chronic kidney disease, and chronic liver disease and cirrhosis. We estimated the hazard ratios (HRs), adjusted hazard ratios (aHRs), and 95% confidence intervals (CIs) for risk of lung cancer in the breast cancer group and non-breast cancer group using Cox proportional hazard models. Sensitivity analysis was also done using propensity score matching. All of the statistical analyses were performed using SAS statistical software, version 9.4 (SAS Institute Inc., Cary, NC).

RESULTS

There were 94,451 breast cancer patients in the breast cancer group and 377,804 patients in the non-breast cancer group in this study. After being stratified by age, urbanization level, and comorbidities, the patients with breast cancer had a significantly higher risk of lung cancer compared with the patients without breast cancer, particularly for those who aged between 20 and 49 years (aHR = 2.10, 95% CI = 1.71-2.58), 50 and 64 years (aHR = 1.35, 95% CI = 1.15-1.58), and those without any comorbidities (aHR = 1.92, 95% CI = 1.64-2.23).

CONCLUSION

Patients with breast cancer had a significantly higher risk of developing second primary lung cancer compared with patients without breast cancer, particularly in younger groups and in those without any comorbidities. The special association may be attributed to some potential risk factors such as genetic susceptibility and long-term exposure to PM2.5, and is supposed to increase public awareness. Further studies are necessary given the fact that inherited genotypes, different subtypes of breast cancer and lung cancer, and other unrecognized etiologies may play vital roles in both cancers' development.

On-Call Duties: The Perceived Impact on Veterinarians' Job Satisfaction, Well-Being and Personal Relationships

Objective: To assess the impact of on-call duties on veterinarians' job satisfaction, well-being and personal relationships.

Design: Cross-sectional survey.

Sample: The sample was obtained from Veterinary Information Network (VIN) members in private practice within the United States.

Procedures: A link to an anonymous online survey was distributed via an email invitation to all Veterinary Information Network (VIN) members with access from August 15, 2017 to October 21, 2017.

Results: A total of 1,945 responses were recorded. The majority of those who reported having on-call duties were female associates. Composite scales were created to assess the impact of on-call shifts on job satisfaction and well-being. Multiple linear regression was conducted and found that gender (p = 0.0311), associate status (p < 0.0001), and age (p = 0.0293) were all significantly associated with on-call related job satisfaction. Additionally, multiple linear regression found that gender (p = 0.0039), associate status (p < 0.0057), and age (p < 0.0001) were all significantly associated with on-call related well-being. On-call shifts were reported by many to have a negative impact on job satisfaction and well-being; this was especially pronounced for female associates. Females had on-call related job satisfaction scores that were, on average, 1.27 points lower than that of males (lower scores equates to lower job satisfaction). Further, females' average on-call related well-being scores were 1.15 points higher than that of males (lower scores equates to higher well-being).

Conclusions and Clinical Relevance: This study suggests that on-call shifts have a negative impact on veterinarian job satisfaction, well-being and personal relationships. The negative impact on job satisfaction and well-being is greatest for female associates. Veterinary medicine has been identified as a stressful occupation that can lead to psychological distress. It is therefore important to critically assess current practices that appear to increase stress and reduce emotional well-being. For this reason, it is suggested that veterinary hospitals explore alternative options to traditional on-call shifts.

Intermittent fasting in the prevention and treatment of cancer

Chronic caloric restriction (CR) has powerful anticarcinogenic actions in both preclinical and clinical studies but may be difficult to sustain. As an alternative to CR, there has been growing interest in intermittent fasting (IF) in both the scientific and lay community as a result of promising study results, mainly in experimental animal models. According to a survey by the International Food Information Council Foundation, IF has become the most popular diet in the last year, and patients with cancer are seeking advice from oncologists about its beneficial effects for cancer prevention and treatment. However, as discussed in this review, results from IF studies in rodents are controversial and suggest potential detrimental effects in certain oncologic conditions. The effects of IF on human cancer incidence and prognosis remain unknown because of a lack of high-quality randomized clinical trials. Preliminary studies suggest that prolonged fasting in some patients who have cancer is safe and potentially capable of decreasing chemotherapy-related toxicity and tumor growth. However, because additional trials are needed to elucidate the risks and benefits of fasting for patients with cancer, the authors would not currently recommend patients undergoing active cancer treatment partake in IF outside the context of a clinical trial. IF may be considered in adults seeking cancer-prevention benefits through means of weight management, but whether IF itself affects cancer-related metabolic and molecular pathways remains unanswered.

Women's health and night shift work: Potential targets for future strategies in breast cancer (Review)

Breast cancer is the leading cause of cancer-associated amongst women worldwide. Several studies have shown that individual, environmental and occupational factors can serve an important role in the onset of breast cancer; although the majority of studies have demonstrated this association, and several studies have investigated the biological pathways, it is impossible to describe with certainty the causal relationship that involve circadian rhythm disruption and melatonin dysregulation with the oncogenic processes. Over the years, due to the introduction of more effective screening tools, an increase in the incidence of breast cancer as well as a decrease in the age at diagnosis has been witnessed. Subsequently, an increasing number of individuals have obtained care at a younger age, which has meant that after surgery and chemotherapy, these workers have had to return to work. In light of these paradigmatic changes, the aim of the present review was to identify potential targets for future organisational strategies that should be adopted in the workplace by occupational physicians, both for prevention and for the return-to-work process of working women who have suffered from breast cancer.

Are we still in the dark? A systematic review on personal daily light exposure, sleep-wake rhythm, and mood in healthy adults from the general population

Insufficient light exposure is assumed to be related to a wide array of health problems, though few studies focus on the role of whole-day light exposure in the habitual setting in the development of these health problems. The current review aims to describe the association between personal light exposure in the habitual setting and sleep-wake rhythm and mood in healthy adults from the general population. Five databases (Embase, Medline Epub, Web of Science, PsycINFO, and Google Scholar) were searched in June 2019. The inclusion criteria included: assessment directly of light exposure on the participants for at least one full day; reporting on both individual personal light exposure and outcomes. The quality of the papers was assessed using the Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies of the National Heart, Lung and Blood Institute. The current review followed the PRISMA guidelines. In total, 8140 papers were identified in the database search. Twenty-five papers were eventually included in this review. All included studies were cross-sectional, and individual light exposure was usually measured with a wrist-worn device. Five studies received a "good" quality rating, 16 received a "fair" rating, and the remaining 4 a "poor" quality rating. The overall quality of the included studies was considered low because of the lack of intervention studies and the fact that light exposure was measured on the wrist. Given the low quality of the included studies, the current review can only provide a first exploration on the association between light exposure and sleep-wake rhythm and mood in healthy adults from the general population. Limited evidence is presented for a positive relationship between the amount and timing of light exposure on the one hand and rest-activity rhythm and some estimates of sleep architecture on the other. The evidence on an association between light exposure and circadian phase, sleep estimates, sleep quality, and mood is conflicting. Data from intervention studies are needed to gain insight into the causal mechanism of the relationship between light exposure and sleep-wake rhythm and mood.

Night-shift work duration and breast cancer risk: an updated systematic review and meta-analysis

BACKGROUND

The International Agency for Research on Cancer (IARC) has classified shift work as a possible human carcinogen. The results of systematic on this topic is contradictory. This systematic review and meta-analysis, therefore, aimed to update the current evidence regarding the relationship between night-shift work duration and breast cancer risk.

METHODS

PubMed, Web of Science, and Scopus as well as reference list of included studies were searched until December 19, 2020. Observational case-control or cohort studies investigating the relationship between the duration of night-shift work and breast cancer in women were included, which all quantified night-shift work exposure. All statistical analyses were done by Stata version 11.2.

RESULTS

Our literature search was resulted in retrieval of 4854 publications from which 26 eligible studies with 1,313,348 participants were included in the meta-analyses. The pooled relative risk (RR) and 95% confidence intervals (CIs) of breast cancer for short-term night-shift workers (< 10 years) was 1.13 (95% CI 1.03-1.24, p = 0.008, I2 = 71.3%), and for long-term night-shift workers (≥ 10 years) was 1.08 (95% CI 0.99-1.17, p = 0.09, I2 = 42.2%), with moderate to substantial statistical heterogeneity observed in both analyses. The results of subgroup analysis showed that flight attendants with long overnight flights were at an elevated risk of breast cancer, but unmeasured confounders limited these results. The risk of breast cancer in case control studies, adjusted for reproductive factors and family history of breast cancer as well as studies with high quality was increased in both short term and long term night-shift workers.

CONCLUSIONS

This systematic review found a positive statistical relationship between night work and breast cancer risk in short-term night-shift workers but no increase was observed in the long-term night-shift workers.

Morning and evening salivary melatonin, sleepiness and chronotype: A comparative study of nurses on fixed day and rotating night shifts

AIMS

To compare morning and evening salivary melatonin levels, sleep quality and chronotype between nurses working fixed day shifts and those working rotating night shifts.

BACKGROUND

Rotating night shift work is an inevitable part of nursing and is a major reason for disrupted sleep.

DESIGN

Cross-sectional comparative design.

PARTICIPANTS AND SETTINGS

We used cluster sampling to recruit 520 female nurses working fixed day and rotating night shifts in the United Arab Emirates.

METHODS

Morning and evening melatonin were measured from corresponding saliva samples. The Pittsburgh Sleep Quality Index used to evaluate sleep quality and self-assessment of preferred circadian times was used to assess participants' chronotypes. Data were collected between October 2017-December 2018.

RESULTS

Rotating night shift nurses had significantly lower evening melatonin compared with the fixed day shift group. No significant difference was found in sleep quality between the groups, although more participants in the rotating night shift group (N = 110, 42.31%) expressed better sleep quality than those in the fixed day group (N = 90, 36.00). Participants in the rotating night shift group expressed better subjective sleep, longer sleep duration, less disturbed sleep and better daily function (p > .05) than the fixed day group. Rotating night shift participants were more likely to have evening or intermediate chronotypes and more likely to report alignment of shift work to their chronotype compared with fixed day shift participants (p = .001). Longer shift duration, marital status and city location were associated with reduced evening melatonin among nurses on rotating night shifts.

CONCLUSION

Rotating night shift nurses showed evidence of better sleep than those from the fixed day shift. Proper shift assignment, chronotype and alignment with shift work appeared to produce better sleep quality.

IMPACT

Organizational policy must consider a novel model for work schedules that allow adequate off-duty days for sleep recovery among nurses.

Light Exposure during Days with Night, Outdoor, and Indoor Work

OBJECTIVE

To assess light exposure during days with indoor, outdoor, and night work and days off work.

METHODS

Light intensity was continuously recorded for 7 days across the year among indoor (n = 170), outdoor (n = 151), and night workers (n = 188) in Denmark (55-56°N) equipped with a personal light recorder. White light intensity, duration above 80, 1000, and 2500 lux, and proportion of red, green, and blue light was depicted by time of the day and season for work days and days off work.

RESULTS

Indoor workers' average light exposure only intermittently exceeded 1000 lux during daytime working hours in summer and never in winter. During daytime working hours, most outdoor workers exceeded 2500 lux in summer and 1000 lux in winter. Night workers spent on average 10-50 min >80 lux when working night shifts. During days off work, indoor and night workers were exposed to higher light intensities than during work days and few differences were seen between indoor, outdoor, and night workers. The spectral composition of light was similar for indoor, outdoor, and night workers during days at and off work.

CONCLUSION

The night workers of this study were during night hours on average exposed for a limited time to light intensities expected to suppress melatonin. The indoor workers were exposed to light levels during daylight hours that may reduce general well-being and mood, especially in winter. Outdoor workers were during summer daylight hours exposed to light levels comparable to those used for the treatment of depression.

Shift work and risk of skin cancer: A systematic review and meta-analysis

Shift work with circadian disruption has been considered as a carcinogenic risk factor for skin cancer. The few prior studies that investigated the association between shift work and skin cancer have inconclusive results. Our main objective was to evaluate the associations between shift work and the risks of different types of skin cancer. We systematically searched PubMed, Web of Science, Cochrane Library, EMBASE and Science Direct until October 2018 for studies that included a relationship between shift work and skin cancer. Our search yielded 193 articles and 9 studies met the criteria for our review. The included studies involved 3,579,147 participants and 17,308 skin cancer cases. Overall, ever shift work, was associated with increased risk of melanoma (RR = 1.10, 95% CI = 1.05–1.16) and a significant decrease in the risk of BCC (RR = 0.90, 95% CI = 0.88–0.93). No association between shift work and the risk of SCC was detected. Interestingly, our dose response analysis demonstrated that the risk of melanoma cumulatively increases by 2% for every year of shift work (RR = 1.02; 95% CI = 1.00–1.03). In conclusion, shift work is associated with increased risk of melanoma and deceased risk of BCC. Further studies are needed to confirm our findings and to elucidate the related potential biological mechanisms.

Night Shift Work-A Risk Factor for Breast Cancer

Shift work is considered a risk factor for some health problems. This study aimed to determine whether night shift work is a significant factor for breast cancer risk. The case-control study was conducted from 2015-2019 in the Łódź region. The case group included 494 women diagnosed with malignant breast cancer; the control group included 515 healthy women. The research tool was an anonymous questionnaire. In the case group, the percentage of women working shift work was 51.9%, whereas in the control group, it was 34.1% (OR = 2.08 (95% CI: 1.61; 2.69)). A more insightful examination of shift work showed that only night work has a significant impact on breast cancer (OR = 2.61 (95% CI: 1.94; 3.53)). Even after considering the effect of other possible cancer factors (like high BMI, smoking, early menstruation, late menopause, pregnancy history, age, place of living, education), the odds of developing cancer were twice as high in the group of shift workers (OR = 2.20 (95% CI: 1.57; 3.08)). Considering a significantly higher risk of cancer among people working at night and a high percentage of such employees in Poland, the government should consider special action in the prophylactic treatment of cancers.

Night-Time Shift Work and Related Stress Responses: A Study on Security Guards

Work-related stress can induce a break in homeostasis by placing demands on the body that are met by the activation of two different systems, the hypothalamic–pituitary–adrenal axis and the sympathetic nervous system. Night-shift work alters the body’s exposure to the natural light–dark schedule and disrupts circadian (daily) rhythms. The greatest effect of night-shift work is the disruption of circadian rhythms. The impact that these disruptions may have on the pathogenesis of many diseases, including cancer, is unknown. This study aims to discover the relationship among three different job activities of security guards and their stress-related responses by evaluating salivary cortisol levels and blood pressure. Methods: Ninety security guards, including night-time workers and night-time and daily-shift workers, were recruited for this study. Each security guard provided two saliva samples before and after three scheduled time points: (i) at 22:00, (ii) at 06:30, and (iii) at 14:00. Results: The results of the study showed a significant alteration in cortisol levels. Night-time shift cortisol levels significantly increased before and after the work shifts. A physiological prevalence of the vagal tone on the cardiocirculatory activity was found during night-shift work. Conclusions: This study indicates that cortisol levels and blood pressure are sensitive markers of biological responses to severe work stress. Shift-change consequences may occur at the end of the night shift when there is a significant increase in the cortisol level and a significant variation in cardiovascular parameters.

Ten-Hour Time-Restricted Eating Reduces Weight, Blood Pressure, and Atherogenic Lipids in Patients with Metabolic Syndrome

In animal models, time-restricted feeding (TRF) can prevent and reverse aspects of metabolic diseases. Time-restricted eating (TRE) in human pilot studies reduces the risks of metabolic diseases in otherwise healthy individuals. However, patients with diagnosed metabolic syndrome often undergo pharmacotherapy, and it has never been tested whether TRE can act synergistically with pharmacotherapy in animal models or humans. In a single-arm, paired-sample trial, 19 participants with metabolic syndrome and a baseline mean daily eating window of ≥14 h, the majority of whom were on a statin and/or antihypertensive therapy, underwent 10 h of TRE (all dietary intake within a consistent self-selected 10 h window) for 12 weeks. We found this TRE intervention improves cardiometabolic health for patients with metabolic syndrome receiving standard medical care including high rates of statin and anti-hypertensive use. TRE is a potentially powerful lifestyle intervention that can be added to standard medical practice to treat metabolic syndrome. VIDEO ABSTRACT.

Working against the biological clock: a review for the Occupational Physician

The master clock of the biological rhythm, located in the suprachiasmatic nucleus of the anterior hypothalamus, synchronizes the molecular biological clock found in every cell of most peripheral tissues. The human circadian rhythm is largely based on the light-dark cycle. In night shift workers, alteration of the cycle and inversion of the sleep-wake rhythm can result in disruption of the biological clock and induce adverse health effects. This paper offers an overview of the main physiological mechanisms that regulate the circadian rhythm and of the health risks that are associated with its perturbation in shift and night workers. The Occupational Physician should screen shift and night workers for clinical symptoms related to the perturbation of the biological clock and consider preventive strategies to reduce the associated health risks.

BRCA1 and BRCA2 Gene Expression: Diurnal Variability and Influence of Shift Work

BRCA1 and BRCA2 genes are involved in DNA double-strand break repair and related to breast cancer. Shift work is associated with biological clock alterations and with a higher risk of breast cancer. The aim of this study was to investigate the variability of expression of BRCA genes through the day in healthy subjects and to measure BRCA expression levels in shift workers. The study was approached in two ways. First, we examined diurnal variation of BRCA1 and BRCA2 genes in lymphocytes of 15 volunteers over a 24-hour period. Second, we measured the expression of these genes in lymphocytes from a group of shift and daytime workers. The change in 24-hour expression levels of BRCA1 and BRCA2 genes was statistically significant, decreasing from the peak at midday to the lowest level at midnight. Lower levels for both genes were found in shift workers compared to daytime workers. Diurnal variability of BRCA1 and BRCA2 expression suggests a relation of DNA double-strand break repair system with biological clock. Lower levels of BRCA1 and BRCA2 found in shift workers may be one of the potential factors related to the higher risk of breast cancer.

Night shift work and risk of breast cancer in women: the Generations Study cohort

Background

It is plausible that night shift work could affect breast cancer risk, possibly by melatonin suppression or circadian clock disruption, but epidemiological evidence is inconclusive.

Methods

Using serial questionnaires from the Generations Study cohort, we estimated hazard ratios (HR) and 95% confidence intervals (95%CI) for breast cancer in relation to being a night shift worker within the last 10 years, adjusted for potential confounders.

Results

Among 102,869 women recruited in 2003–2014, median follow-up 9.5 years, 2059 developed invasive breast cancer. The HR in relation to night shift work was 1.00 (95%CI: 0.86–1.15). There was a significant trend with average hours of night work per week (P = 0.035), but no significantly raised risks for hours worked per night, nights worked per week, average hours worked per week, cumulative years of employment, cumulative hours, time since cessation, type of occupation, age starting night shift work, or age starting in relation to first pregnancy.

Conclusions

The lack of overall association, and no association with all but one measure of dose, duration, and intensity in our data, does not support an increased risk of breast cancer from night shift work in women.

Shift Work Disorder

Shift work and its negative consequences are becoming more relevant as the economy becomes increasing globalized. For many individuals, shift work serves as a significant biological and psychosocial challenge leading to Shift Work Disorder (SWD). Beyond the symptoms of sleep and excessive sleepiness, the range of consequences for health and daily functioning in those with SWD are reviewed, along with evidence-based recommendations for clinical management, including comprehensive clinical assessments and intervention strategies that target multiple domains through pharmacologic and nonpharmacologic methods. A review of important recent scientific and technological developments for assessment and intervention is also provided.

Systems Biology Approaches and Precision Oral Health: A Circadian Clock Perspective

A vast majority of the pathophysiological and metabolic processes in humans are temporally controlled by a master circadian clock located centrally in the hypothalamic suprachiasmatic nucleus of the brain, as well as by specialized peripheral oscillators located in other body tissues. This circadian clock system generates a rhythmical diurnal transcriptional-translational cycle in clock genes and protein expression and activities regulating numerous downstream target genes. Clock genes as key regulators of physiological function and dysfunction of the circadian clock have been linked to various diseases and multiple morbidities. Emerging omics technologies permits largescale multi-dimensional investigations of the molecular landscape of a given disease and the comprehensive characterization of its underlying cellular components (e.g., proteins, genes, lipids, metabolites), their mechanism of actions, functional networks and regulatory systems. Ultimately, they can be used to better understand disease and interpatient heterogeneity, individual profile, identify personalized targetable key molecules and pathways, discover novel biomarkers and genetic alterations, which collectively can allow for a better patient stratification into clinically relevant subgroups to improve disease prediction and prevention, early diagnostic, clinical outcomes, therapeutic benefits, patient's quality of life and survival. The use of “omics” technologies has allowed for recent breakthroughs in several scientific domains, including in the field of circadian clock biology. Although studies have explored the role of clock genes using circadiOmics (which integrates circadian omics, such as genomics, transcriptomics, proteomics and metabolomics) in human disease, no such studies have investigated the implications of circadian disruption in oral, head and neck pathologies using multi-omics approaches and linking the omics data to patient-specific circadian profiles. There is a burgeoning body of evidence that circadian clock controls the development and homeostasis of oral and maxillofacial structures, such as salivary glands, teeth and oral epithelium. Hence, in the current era of precision medicine and dentistry and patient-centered health care, it is becoming evident that a multi-omics approach is needed to improve our understanding of the role of circadian clock-controlled key players in the regulation of head and neck pathologies. This review discusses current knowledge on the role of the circadian clock and the contribution of omics-based approaches toward a novel precision health era for diagnosing and treating head and neck pathologies, with an emphasis on oral, head and neck cancer and Sjögren's syndrome.

Working Time Society consensus statements: Individual differences in shift work tolerance and recommendations for research and practice

There is no standard definition of shift work universally, and no validated report of complete biological adjustment to shift work in workers. Similarly, the evidence for shift work tolerance is limited due to a small number of studies and a narrow range of outcome measures. This paper discusses evidence to date regarding individual differences in shift work tolerance and highlights areas for future research and recommendations for workplace practice. The few factors that are consistently associated with perceived or actual shift work tolerance are young age, low scores of morningness or being a late chronotype, low scores of languidity and neuroticism, high scores on extraversion, internal locus of control and flexibility and male sex. An important first step is to differentiate between factors that are potentially modifiable, such as those that are determined by lifestyle choices, and those factors specific to the working time arrangement. Identifying determinants of shift work tolerance and the ability to adjust to shift work, whether they are innate and/or acquired mechanisms, is important so workers who are less likely to tolerate shift work well can be self-identified and supported with appropriate harm/risk minimization strategies. This paper also identifies important areas for future research with the goal of increasing the evidence base on which we can develop evidence-based harm mitigation strategies for shift workers.

Tales from the Night:: Emergency MR Imaging in Pediatric Patients after Hours

Overnight in-house radiology has rapidly become an important part of contemporary practice models, and is increasingly the norm in pediatric radiology. MR imaging is an indispensable first-line and problem-solving tool in the pediatric population. This has led to increasingly complex MR imaging being performed "after hours" on pediatric patients. This article reviews the factors that have led to widespread overnight subspecialty radiology and the associated challenges for overnight radiologists, and provides an overview of up-to-date imaging techniques and imaging findings of the most common indications for emergent MR imaging in the pediatric population.

Differences in twenty-four-hour profiles of blue-light exposure between day and night shifts in female medical staff

Light is the strongest zeitgeber currently known for the synchronization of the human circadian timing system. Especially shift workers are exposed to altered daily light profiles. Our objective is the characterization of differences in blue-light exposures between day and night shift taking into consideration modifying factors such as chronotype. We describe 24-hour blue-light profiles as measured with ambient light data loggers (LightWatcher) during up to three consecutive days with either day or night shifts in 100 female hospital staff including 511 observations. Linear mixed models were applied to analyze light profiles and to select time-windows for the analysis of associations between shift work, individual factors, and log mean light exposures as well as the duration of darkness per day. Blue-light profiles reflected different daily activities and were mainly influenced by work time. Except for evening (7-9 p.m.), all time windows showed large differences in blue-light exposures between day and night shifts. Night work reduced the duration of darkness per day by almost 4 h (β^ = -3:48 hh:mm, 95% CI (-4:27; -3.09)). Late chronotypes had higher light exposures in the morning and evening compared to women with intermediate chronotype (e.g. morning β^ = 0.50 log(mW/m²/nm), 95% CI (0.08; 0.93)). Women with children had slightly higher light exposures in the afternoon than women without children (β^ = 0.48, 95% CI (-0.10; 1,06)). Time windows for the description of light should be chosen carefully with regard to timing of shifts. Our results are helpful for future studies to capture relevant light exposure differences and potential collinearities with individual factors. Improvement of well-being of shift workers with altered light profiles may therefore require consideration of both - light at the workplace and outside working hours.

Prognostic Value of Lymphovascular Invasion in Node-Negative Upper Urinary Tract Urothelial Carcinoma Patients Undergoing Radical Nephroureterectomy

PURPOSE

This study aimed to evaluate the prognostic impact of lymphovascular invasion (LVI) in patients treated with radical nephroureterectomy (RNU) for upper urinary tract urothelial carcinoma (UTUC).

MATERIALS AND METHODS

We collected data from 180 patients who were treated with RNU from 2005 to 2013 at our institution. The Kaplan-Meier method with log-rank test and Cox proportional hazards regression models were used for univariate and multivariate analyses.

RESULTS

LVI was present in 28 patients (15.6%), which was associated with higher pathological tumor stage (p<0.001), tumor necrosis (p=0.012), lymph node metastasis (p=0.017) and multifocality (p=0.012). On multivariate analysis, LVI was an independent prognostic factor of recurrence-free survival [RFS: hazard ratio (HR)=2.954; 95% confidence interval (CI)=1.539-5.671; p=0.001] and cancer-specific survival (CSS: HR=3.530; 95% CI=1.701-7.325; p=0.001) in all patients. In patients with node-negative UTUC, LVI was also a significant predictor of RFS (HR=3.732; 95% CI 1.866-7.464; p<0.001) and CSS (HR=3.825; 95% CI=1.777-8.234; p=0.001).

CONCLUSION

LVI status was an independent predictor in patients with UTUC who underwent RNU. The estimate of LVI could help physicians identify high-risk patients and make a better medication regimen of adjuvant chemotherapy.

Shiftwork Association with Cardiovascular Diseases and Cancers Among Healthcare Workers: A Literature Review

The round-the-clock demands of healthcare services, coupled with the shortage of healthcare providers in many parts of the world, have made shiftwork widespread among healthcare workers. Understanding how to mitigate unfavourable effects of shiftwork on well-being is essential to improve health promotion, to prevent disease prevention, and to increase quality of life. This comprehensive review aims to present evidence linking shiftwork with cardiovascular diseases and cancers among healthcare workers. Several studies have demonstrated evidence indicating the relationship between long-term exposure to shiftwork tempo and a higher risk of cardiovascular diseases. Health workers are increasingly witnesing unfavourable effects of shiftwork on their health state. Shiftwork disturbs circadian rhythm and cardiopulmonary processes, leading to adverse health outcomes. Increasing prevalence of shiftwork in healthcare industries due to population expansion and public health threat of cancers call for investigation towards a better understanding of the underlying mechanism of shiftwork-induced diseases. The shift work period has been considered in different studies using various criteria, resulting in inconsistent definition of measurement criteria leading to misclassification of the study population. There is a need for a more considerable and holistic effort towards standardization of shiftwork definition and conduct an assessment to establish a more conveniently appliacable framework for intervention strategies.

Sex Differences in the Association between Night Shift Work and the Risk of Cancers: A Meta-Analysis of 57 Articles

Objectives

To identify the association between night shift work and the risk of various cancers with a comprehensive perspective and to explore sex differences in this association.

Methods

We searched PubMed, Embase, and Web of Science for studies on the effect of night shift work on cancer, including case-control, cohort, and nested case-control studies. We computed risk estimates with 95% confidence intervals (CIs) in a random or fixed effects model and quantified heterogeneity using the I ² statistic. Subgroup, metaregression, and sensitivity analyses were performed to explore potential sources of heterogeneity. Contour-enhanced funnel plots and the trim and fill method were used together to analyze bias. Linear dose-response analysis was used to quantitatively estimate the accumulative effect of night shift work on the risk of cancer.

Results

Fifty-eight studies were eligible for our meta-analysis, including 5,143,838 participants. In the random effects model, the pooled odds ratio (OR) of cancers was 1.15 (95% CI = 1.08-1.22, P < 0.001; I ² = 76.2%). Night shift work increased the cancer risk in both men (OR = 1.14, 95% CI = 1.05-1.25, P = 0.003) and women (OR = 1.12, 95% CI = 1.04-1.20, P = 0.002). Subgroup analyses showed that night shift work positively increased the risk of breast (OR = 1.22, 95% CI = 1.08-1.38), prostate (OR = 1.26, 95% CI = 1.05-1.52), and digestive system (OR = 1.15, 95% CI = 1.01-1.32) cancers. For every 5 years of night shift work, the cancer risk increased by 3.2% (OR = 1.032, 95% CI = 1.013-1.051).

Conclusion

This is the first meta-analysis identifying the positive association between night shift work and the risk of cancer and verifying that there is no sex difference in the effect of night shift work on cancer risk. Cancer risk increases with cumulative years of night shift work.

Feasibility and acceptability of brief behavioral therapy for cancer-related insomnia: effects on insomnia and circadian rhythm during chemotherapy: a phase II randomised multicentre controlled trial

BACKGROUND

This phase II RCT was conducted to determine the feasibility and acceptability of brief behavioral therapy for cancer-related insomnia (BBT-CI) in breast cancer patients undergoing chemotherapy. We also assessed the preliminary effects of BBT-CI on insomnia and circadian rhythm in comparison to a Healthy Eating Education Learning control condition (HEAL).

METHODS

Of the 71 participants recruited, 34 were randomised to receive BBT-CI and 37 to receive HEAL. Oncology staff was trained to deliver the intervention in four community clinics affiliated with the NCI. Insomnia was assessed with the Insomnia Severity Index (ISI), and circadian rhythm was assessed using a wrist-worn actiwatch.

RESULTS

Community staff interveners delivered 72% of the intervention components, with a recruitment rate of 77% and an adherence rate of 73%, meeting acceptability and feasibility benchmarks. Those randomised to BBT-CI improved their ISI scores by 6.3 points compared to a 2.5-point improvement in those randomised to HEAL (P = 0.041). Actigraphy data indicated that circadian functioning improved in the BBT-CI arm as compared to the HEAL arm at post-intervention (all P-values <0.05).

CONCLUSIONS

BBT-CI is an acceptable and feasible intervention that can be delivered directly in the community oncology setting by trained staff. The BBT-CI arm experienced significant improvements in insomnia and circadian rhythm as compared to the control condition.

Occupational inequalities in female cancer incidence in Japan: Hospital-based matched case-control study with occupational class

BACKGROUND

Socioeconomic inequalities in female cancer incidence have previously been undocumented in Japan.

METHODS

Using a nationwide inpatient dataset (1984-2016) in Japan, we identified 143,806 female cancer cases and 703,157 controls matched for sex, age, admission date, and admitting hospital, and performed a hospital-based matched case-control study. Based on standardized national classification, we categorized patients' socioeconomic status (SES) by occupational class (blue-collar, service, professional, manager), cross-classified by industry sector (blue-collar, service, white-collar). Using blue-collar workers in blue-collar industries as the reference group, we estimated the odds ratio (OR) for each cancer incidence using conditional logistic regression with multiple imputation, adjusted for major modifiable risk factors (smoking, alcohol consumption).

RESULTS

We identified lower risks among higher-SES women for common and overall cancers: e.g., ORs for managers in blue-collar industries were 0.67 (95% confidence interval [CI], 0.46-0.98) for stomach cancer and 0.40 (95% CI, 0.19-0.86) for lung cancer. Higher risks with higher SES were evident for breast cancer: the OR for professionals in service industries was 1.60 (95% CI, 1.29-1.98). With some cancers, homemakers showed a similar trend to subjects with higher SES; however, the magnitude of the OR was weaker than those with higher SES.

CONCLUSIONS

Even after controlling for major modifiable risk factors, socioeconomic inequalities were evident for female cancer incidence in Japan.

Training the Circadian Clock, Clocking the Drugs, and Drugging the Clock to Prevent, Manage, and Treat Chronic Diseases

Daily rhythms in behavior, physiology, and metabolism are an integral part of homeostasis. These rhythms emerge from interactions between endogenous circadian clocks and ambient light-dark cycles, sleep-activity cycles, and eating-fasting cycles. Nearly the entire primate genome shows daily rhythms in expression in tissue- and locus-specific manners. These molecular rhythms modulate several key aspects of cellular and tissue function with profound implications in public health, disease prevention, and disease management. In modern societies light at night disrupts circadian rhythms, leading to further disruption of sleep-activity and eating-fasting cycles. While acute circadian disruption may cause transient discomfort or exacerbate chronic diseases, chronic circadian disruption can enhance risks for numerous diseases. The molecular understanding of circadian rhythms is opening new therapeutic frontiers placing the circadian clock in a central role. Here, we review recent advancements on how to enhance our circadian clock through behavioral interventions, timing of drug administration, and pharmacological targeting of circadian clock components that are already providing new preventive and therapeutic strategies for several diseases, including metabolic syndrome and cancer.

Clocking in to immunity

Circadian rhythms are a ubiquitous feature of virtually all living organisms, regulating a wide diversity of physiological systems. It has long been established that the circadian clockwork plays a key role in innate immune responses, and recent studies reveal that several aspects of adaptive immunity are also under circadian control. We discuss the latest insights into the genetic and biochemical mechanisms linking immunity to the core circadian clock of the cell and hypothesize as to why the immune system is so tightly controlled by circadian oscillations. Finally, we consider implications for human health, including vaccination strategies and the emerging field of chrono-immunotherapy.