Circadian Disruption from Night-shift Work and Colorectal Cancer Risk: A Systematic Review and Meta-analysis
Rabiu Musa Isah *
Department of Human Physiology, Faculty of Basic Medical Sciences, College of Medical Sciences, Federal University of Health Sciences, Azare, Bauchi State, Nigeria.
Mahdi Gambo Dissi
Department of Human Physiology, Faculty of Basic Medical Sciences, College of Health Sciences, Bayero University, Kano, Nigeria.
Abdul-karim Yusuf Idris
Department of Veterinary, Physiology and Biochemistry, University of Jos, Plateau State, Nigeria.
Saad Zubair Maitama
Department of Human Physiology, Faculty of Basic Medical Sciences, College of Health Sciences, Bayero University, Kano, Nigeria.
Basira Idris Musa
Department of Human Physiology, Faculty of Basic Medical Sciences, College of Health Sciences, Bayero University, Kano, Nigeria.
Muhammad Ali Salim
Department of Human Physiology, Faculty of Basic Medical Sciences, College of Health Sciences, Bayero University, Kano, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Background: Night-shift work significantly disrupts the circadian rhythm and has been classified by the International Agency for Research on Cancer as a probable human carcinogen. However, evidence regarding its association with colorectal cancer (CRC) remains inconsistent. This systematic review and meta-analysis aimed to assess the relationship between night-shift work and the risk of CRC.
Methods: Following PRISMA 2020 guidelines, registered with PROSPERO (CRD420251014202), we systematically searched PubMed, ProQuest, PsycINFO, Cochrane Library, and Google Scholar for cohort and case-control studies published between January 2020 and March 2025. Studies assessing night-shift work exposure with CRC outcomes and effect estimates were included. Study quality was assessed using the Newcastle-Ottawa Scale. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using fixed- effects models, with subgroup, sensitivity and dose-response analyses.
Results: Five studies involving 143,058 participants were included. Meta-analysis demonstrated a significantly increased CRC risk among individuals exposed to ALAN or night- shift work (pooled OR = 1.62; 95% CI: 1.28–2.05; p < 0.001), with moderate heterogeneity (I² = 45%). Subgroup analyses revealed stronger associations among females (OR = 1.29) and European populations (OR = 1.62). A dose-response relationship was observed, with long-term exposure (≥10 years) associated with higher risk (HR = 1.64, 95% CI: 1.01–2.66). Sensitivity analyses confirmed robustness, and no significant publication bias was detected (Begg‘s test p = 0.35).
Conclusion: This study suggests that night-shift work may increase the risk of colorectal cancer, highlighting circadian disruption as a potentially modifiable occupational risk factor. Future research employing objective measures of light exposure and sleep disruption is needed to clarify this association.
Keywords: Circadian rhythm, night-shift schedule, colorectal neoplasm, meta-analysis as topic