Article Text
Abstract
Background Night shift work can disrupt circadian rhythm and cause chronic sleep deprivation, which might increase the risk of lymphoma through immunosuppression and oxidative stress.
Material and methods We investigated the association between night shift work and risk of lymphoma subtypes in 867 incident cases and 774 controls, who participated in a multicentre Italian study between 2011 and 2017. Based on questionnaire information, occupational experts assessed the lifetime probability of night shift work, the total number of night shifts and years of night shift work among study participants. OR and 95% CI for lymphoma and its major subtypes associated with night shift work was calculated with logistic regression, adjusting by age, gender, education, study area, marital status and family history of haemolymphatic cancer.
Results Ever working night shifts was associated with an increase in the risk of chronic lymphocytic leukaemia (CLL) (OR 1.9, 95% CI 1.14 to 3.32), which was highest after a 15–34 years latency. However, there was not a linear increase in risk by probability of exposure, years of night shift work, nor lifetime number of night shifts whether under rotating or permanent work schedules. Risk of lymphoma overall, B cell lymphoma (BCL), its major subtypes other than CLL, and other less prevalent BCL subtypes combined did not show an association.
Conclusions We found conflicting evidence of an association between night shift work and the risk of CLL. We did not observe an association with other lymphoma subtypes.
- hematology
- sleep
- retrospective studies
- shift work schedule
- occupational health
Data availability statement
Data are available on reasonable request. Data are preserved in the digital archives of the Department of Medical Sciences and Public Health of the Cagliari University in aggregated form, and they are publicly available as such. Please contact PC (pcocco@unica.it) for any requests.
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Data availability statement
Data are available on reasonable request. Data are preserved in the digital archives of the Department of Medical Sciences and Public Health of the Cagliari University in aggregated form, and they are publicly available as such. Please contact PC (pcocco@unica.it) for any requests.
Footnotes
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Contributors PC is the author responsible for the overall content as the guarantor, conceived the study, supervised and revised the epidemiological analysis, revised the draft manuscript, wrote the final version, and provided overall supervision; FM, AM, IP and MiP conducted the epidemiological analysis and drafted the manuscript; MaP, AG, GMF, SP, RZ, GCL and MZ conducted the study in the field; CM, LM, GM, GMF, LV, RZ, AS and SDM were responsible for data management and revised the manuscript; PC, SP and LM coordinated the exposure assessment; EA and MoP revised the manuscript and provided overall supervision. All authors participated in the interpretation of the results, provided critical feedback and approved the final version.
Funding This study was funded within the following programmes: (1) the Italian Ministry for Education, University and Research (PRIN 2007 Prot. 2007WEJLZB and PRIN 2009 Prot. 20092ZELR2); (7) the Italian Association for Cancer Research (IG 2011/11855).
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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