How the Intensity of Night Shift Work Affects Breast Cancer Risk

Szkiela, Marta; Kusideł, Ewa; Makowiec-Dąbrowska, Teresa; Kaleta, Dorota

doi:10.3390/ijerph18094570

Cited by 17 publications

(23 citation statements)

References 35 publications

(51 reference statements)

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“…The observed trend of increased risk by longer exposure to night shift work is supported by earlier studies,2 but with some exceptions 7 21. Case–control studies with much more detailed exposure indicators than available in the cohort studies show generally more positive trends in the association of longer duration of night shifts and risk of breast cancer (eg, refs 19 22 23).…”

Section: Discussionsupporting

confidence: 54%

Shift work with and without night shifts and breast cancer risk in a cohort study from Finland

et al. 2022

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ObjectivesTo examine the association of shift work with and without night work with breast cancer among women in the public sector.MethodsUsing the Finnish Public Sector cohort study (N=33 359, mean age of 40.6 years at baseline), we investigated the associations of shift work and potential confounders with incident breast cancer. Exposure to permanent day work or shift work was defined from first two consecutive surveys from 2000, 2004, 2008 or 2012 and past information on exposure in a subcohort (n=20 786). Incident cases of breast cancer (n=1129) were retrieved from the National Cancer Register and the cohort members were followed to the end of 2016. HR and 95% CI from Cox proportional hazard regression models were calculated.ResultsShift work with and without night shifts was not overall associated with breast cancer. When stratified according to age, both shift work without nights (HR 2.01, 95% CI 1.12 to 3.60) and shift work with nights (OR 2.05, 95% CI 1.04 to 4.01) were associated with an increased risk after a period of 10 years or more follow-up among women aged 50 years or older, when adjusted for age, socioeconomic status, children, smoking, alcohol and body mass index. In a subgroup with past information on exposure to shift work, the increased risk by longer exposure to shift work was not significant.ConclusionsThis study provides support for an increased risk of breast cancer among elderly shift workers. However, insufficient information on exposure and intensity of night work may attenuate the risk estimates.

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Section: Discussionsupporting

confidence: 54%

Shift work with and without night shifts and breast cancer risk in a cohort study from Finland

et al. 2022

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“…The jet lag protocol used here mimics the effects of rotating shift work or frequent eastbound trans-meridian flights and has been previously shown to cause severe perturbations of circadian rhythmicity ( 6, 7, 9 ). A recent epidemiological study showed that night shift work affects the risk of developing breast cancer by 2.34 times ( 53 ). Consistent with the results of published studies ( 7 ), we found that CRD affected the rhythmicity of many clock genes (e.g., Clock, Bmal1, Per1 , and Cry1 ) in the mammary glands; however, Per2 expression remained rhythmic after CRD, indicating that Per2 is more sensitive to phase entrainment signals of molecular oscillators in peripheral tissues.…”

Section: Discussionmentioning

confidence: 99%

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

Ogunlusi,

Sarkar,

Chakrabarti

et al. 2024

Preprint

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Epidemiological studies have shown that circadian rhythm disruption (CRD) caused by shift work or frequent jet lag is associated with the risk of breast cancer development. However, the role of CRD in mammary gland morphology and aggressive mammary tumorigenesis and the molecular mechanisms underlying CRD and cancer risk remain unknown. We found that chronic CRD disrupted mouse mammary gland morphology and increased tumor burden and lung metastasis in a genetically engineered mouse model of aggressive breast cancer and induced an immunosuppressive tumor microenvironment by enhancing leukocyte immunoglobulin-like receptor 4a (LILRB4a or LILRB4) expression. Moreover, CRD increased the M2 macrophage (anti-inflammatory) and regulatory T-cell populations but decreased the M1 macrophage (proinflammatory) populations. These findings identify and implicate LILRB4a as a link between CRD and aggressive mammary tumorigenesis.

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“…Younger workers have fewer chronic diseases, can recover from illness and injury earlier, and are more likely to have absences due to minor health problems or motivational issues compared with older workers 33 . In terms of the night shift, shift work negatively affects an employee's health and can increase the risk of cardiovascular diseases, gastrointestinal disorders, and cancer 35–37 . It was suggested that the intensity or the number of consecutive night shifts was a risk factor for a long‐term SA, 38,39 although detailed schedules of shift work were not included in this study, such as rotation types, the number of consecutive night shifts or intensity, and years of shift work.…”

Section: Discussionmentioning

confidence: 99%

Sickness absence among employees of healthcare organizations in the public sector in Mongolia: A cross-sectional study

Sukhee

Sovd

Khaltar

et al. 2023

Journal of Occupational Health

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Objectives This study aimed to understand the rate of sickness absence (SA) among employees of public healthcare organizations in Mongolia, to identify factors associated with long‐term SA, and to estimate costs due to SA. Methods This cross‐sectional study included employees of public healthcare organizations who had certified SA from 2016 to 2018. Sociodemographic and occupational characteristics of absentees and the data on absences were collected. A logistic regression analysis was performed to identify factors associated with long‐term SA (≥15 days) among employees who had SA. Absence parameters and the average costs due to SA were calculated and the total cost due to SA at all public healthcare organizations was estimated. Results From 2016 to 2018, there were 13 653 absentees and 21 043 SA, and the absence rate was 0.9%. The average absence length per absence and absentee were 9.63 days and 14.85 days, respectively. Factors associated with long‐term SA were age ≥40 years, 10–19 years in employment, working at the second and tertiary levels, and night shift. The average cost per absentee was 295.5 USD, and the estimated total cost for all health organizations was 1 796 993 USD per year. Conclusions The absence rate was 0.9% and older age, longer work experience, higher organizational level, and night shift were associated with taking a long‐term SA. To reduce the costs of absenteeism and promote the health of employees in healthcare organizations, policymakers should review the policies related to SA and develop national guidelines on SA for employers, healthcare managers, and employees.

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How the Intensity of Night Shift Work Affects Breast Cancer Risk

Cited by 17 publications

References 35 publications

Shift work with and without night shifts and breast cancer risk in a cohort study from Finland

Shift work with and without night shifts and breast cancer risk in a cohort study from Finland

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

Sickness absence among employees of healthcare organizations in the public sector in Mongolia: A cross-sectional study

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