Night shifts, breast cancer link disputed
medwireNews: Night shift work may not elevate the risk of breast cancer after all.
The findings of the meta-analysis are in contrast to those of the 2007 WHO report that classified circadian rhythm-disrupting night work as a probable carcinogen, based mainly on animal studies, the UK team says in the Journal of the National Cancer Institute.
The current analysis of 10 prospective studies comprising 1.4 million women found no association between night shifts and breast cancer incidence, even in the case of long-term shift work (>20 or >30 years).
Ruth Travis, from the University of Oxford, and co-researchers included three new analyses of the Million Women Study, EPIC-Oxford and UK Biobank cohorts, none of which independently showed a link.
Although they cannot rule out a small increase in the relative risk of breast cancer incidence and also urge further follow-up, Travis et al conclude that “the prospective evidence now available shows that classification of night shift work as a probable human (breast) carcinogen is no longer justified.”
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