The role of sleep traits in prostate, endometrial, and epithelial ovarian cancers: An observational and Mendelian randomisation study

Background:
Sleep traits may influence cancer risk; however, their associations with prostate (PCa), endometrial (ECa), and epithelial ovarian (EOCa) cancer remain unclear.

Methods:
We conducted an observational analysis using the UK Biobank cohort and a two-sample Mendelian randomisation (MR) analysis to investigate the association between six sleep traits-duration, chronotype, insomnia, daytime napping, daytime sleepiness, and snoring-with PCa, ECa, and EOCa risk. Cox proportional hazards models were used for the observational analysis, while the inverse variance-weighted (IVW) method was applied in MR, with multiple sensitivity analyses. A Bonferroni correction was applied to account for multiple testing.

Results:
Among 8608 PCa, 1079 ECa, and 680 EOCa incident diagnoses (median follow-up: 6.9 years), snoring was associated with reduced EOCa risk (HR=0.78, 95 %CI: 0.62–0.98), while daytime sleepiness was associated with increased EOCa risk (HR=1.23, 95 %CI: 1.03–1.47). However, these associations were not confirmed in MR. MR suggested higher odds of PCa (ORIVW=1.05, 95 %CI: 1.01–1.11) and aggressive PCa (ORIVW=1.10, 95 %CI: 1.02–1.19) for evening compared to morning chronotype. None of the findings survived multiple testing correction.

Conclusion:
Sleep traits were not associated with PCa, ECa, or EOCa risk; however, an evening chronotype may increase PCa risk. Further research is needed to verify this association and investigate potential underlying mechanisms.