Night shift work and prostate cancer: a large cohort study from UK Biobank and Mendelian randomisation study.

OBJECTIVE

The global concern regarding the health implications of night shift work has escalated. Nevertheless, variations exist in the observed association between night shift work and prostate cancer (PCa). This study aims to systematically explore the association between night shift work and the risk of PCa.

DESIGN

Cohort study and Mendelian randomisation (MR) study were used.

SETTING

Cohort study data was from the UK Biobank (UKB). MR study using data was from the Finngen study and UKB through the Integrative Epidemiology Unit (IEU) Open Genome-Wide Association Study Project.

PARTICIPANTS

Participants without prior PCa in paid employment or self-employment were include in the current work schedule cohort, participants without PCa who provided employment history formed the lifetime night shift work cohort.

MAIN OUTCOME MEASURES

The outcome, incident PCa, was obtained from cancer register through linkage to national cancer databases. National cancer registries centralised information received from separate regional cancer centres around the UK.

RESULTS

A total of 130 853 participants were included in the current work schedule cohort, while the lifetime night shift work cohort comprised 49 511 participants. Over a median follow-up duration of 13.9 years, the current work schedule cohort witnessed 4993 incident cases of PCa, while the lifetime night shift work cohort recorded 2022 PCa cases. In the analysis of the current work schedule, final model showed that no significant association was found between shift work and PCa risk, whether it involved shift but no night shifts (HR 0.96, 95% CI 0.85 to 1.08), some night shifts (HR 1.16, 95% CI 0.99 to 1.33) and usual night shifts (HR 1.01, 95% CI 0.85 to 1.19). In the analysis of the average frequency of night shift work, final model showed no significant impact of different night shift frequencies (<3/month: HR 0.97, 95% CI 0.73 to 1.29; 3-8/month: HR 0.99, 95% CI 0.83 to 1.19; >8/month: HR 0.89, 95% CI 0.73 to 1.07) on the risk of PCa. No significant association was found for either <10 years (HR 0.89, 95% CI 0.72 to 1.09) or ≥10 years (HR 1.00, 95% CI 0.86 to 1.16) of night shift work. Subsequent subgroup and sensitivity analyses demonstrated consistent results without significant alterations. Furthermore, in the two-sample MR analysis, no statistically significant causal relationship was identified between night shift work and the incidence of PCa.

CONCLUSION

In both the cohort studies and MR analysis, our investigation did not find any association between night shift work and PCa.