Nightshift work and risk of breast and prostate cancer: a systematic review and meta-analysis, 2012-2023
Abstract
Background: The International Agency for Research on Cancer classifies night shift work as Group 2A, a probable human carcinogen. This study updates the evidence on the association between night shift work and the risk of breast and prostate cancer.
Methods: Searches were conducted in PubMed and Web of Science. Case-control and cohort studies were included if they assessed night work as a risk factor for breast or prostate cancer, had =100 participants, provided full text in English or Spanish, scored =6 on the Newcastle-Ottawa Scale, and reported relative risks or odds ratio with 95% confidence interval. Heterogeneity and study quality were evaluated. Data synthesis followed PRISMA guidelines.
Results: Twenty-one studies including 586,890 participants were analysed. For breast cancer, significant association were found only in cohort studies, both overall (RR=0.82; 95%CI: 0.67-0.99; I2=91%) and for <10 years of night work (RR=0.75; 95% CI: 0.68-0.82; I2=0%). Average study quality was acceptable (score 7), although heterogeneity was substantial. For prostate cancer, case-control studies reported an OR of 1.14 (95%CI; 1.02-1.27; I2=25%). For exposures =10 years, both RR (2.20; 95%CI: 1.35-3.59) and OR (1.16; 95%CI: 1.03-1.30) were significant. Overall quality was moderate (score 6) with low heterogeneity (25%).
Conclusions: Weak associations between night shift work and prostate cancer are observed in case-control studies and among individuals with =10 years of exposure, but…
How strong is the evidence?
Evidence Hub reads this as a meta-analysis, done in people. Its evidence level is 1 of 5 (Highest · pooled evidence). Pooled evidence from several studies sits at the top of the evidence pyramid. Reported size: 586,890 participants or records.
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