Nightshift work and risk of breast and prostate cancer: a systematic review and meta-analysis, 2012-2023.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of observational (cohort and case-control) studies
PubMed 41473964 · doi:10.23938/ASSN.1149
What was done
A systematic review and meta-analysis following PRISMA guidelines examined the association between night shift work and breast or prostate cancer risk using PubMed and Web of Science searches (2012–2023). Included studies were cohort or case-control designs with at least 100 participants, a Newcastle-Ottawa Scale quality score of 6 or higher, full text in English or Spanish, and reported relative risks (RR) or odds ratios (OR) with 95% confidence intervals.
What was found
Twenty-one studies with 586,890 participants were analyzed. For breast cancer, significant associations were reported only in cohort studies, both overall (RR 0.82; 95% CI: 0.67–0.99; I² = 91%) and for under 10 years of night work (RR 0.75; 95% CI: 0.68–0.82; I² = 0%). For prostate cancer, case-control studies showed an OR of 1.14 (95% CI: 1.02–1.27; I² = 25%). For exposure of 10 or more years, both cohort RR (2.20; 95% CI: 1.35–3.59) and case-control OR (1.16; 95% CI: 1.03–1.30) were statistically significant.
Why it matters
These findings update evidence regarding night work carcinogenicity, showing potential long-term risk associations for prostate cancer but an absence of increased risk findings for breast cancer.
Limits
All included studies were observational, which limits causal inference due to potential confounding and exposure misclassification. The breast cancer cohort analysis showed substantial heterogeneity (I² = 91%), and study inclusion was restricted to English- and Spanish-language articles published between 2012 and 2023.
Cited by
- context Shift work and mistimed circadian rhythms are associated with a fourfold increase in cancer risk.