Article Text

Download PDFPDF
Shift work and breast cancer: do we need more evidence and what should this be?
  1. Kyriaki Papantoniou1,2,
  2. Manolis Kogevinas1,2
  1. 1Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain
  2. 2CIBER Epidemiología y Salud Pública (CIBERESP), Madrid, Spain
  1. Correspondence to Professor Manolis Kogevinas, Centre for Research in Environmental Epidemiology (CREAL), Doctor Aiguader 88, Barcelona 08003, Spain; kogevinas{at}

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.

Research on circadian disruption and cancer was stimulated by the 2007 evaluation by the International Agency for Research on Cancer of light at night and circadian rhythm disruption as probably carcinogenic to humans.1 Circadian rhythm disruption ultimately affects a large part of the population in modern societies and not only those in shift work. The experimental evidence on light at night and breast cancer is very strong, clearly showing the potential for light at night and circadian rhythm disruption to cause cancer. The evidence from epidemiological studies is mostly positive notwithstanding inconsistencies and lack of a clear dose–response. Since the first meta-analysis by Megdal et al,2 several systematic reviews and meta-analyses have been performed, three of them published in 2013, attempting to summarise the association between night shift work and breast cancer risk. Two3 ,4 of the three recent reviews concluded that the epidemiological evidence is overall weak or insufficient, whereas the third review5 supported the hypothesis. Even though inconclusive, all reviews highlighted the methodological limitations of the existing studies and the heterogeneity between studies in methods including basic definitions of exposure. So, do we need more evidence and what should this be?

The paper by Grundy et al6 provides more evidence supporting the association between shift work and breast cancer risk, as most case–control studies have done so far. In this well-conducted large case–control study, a twofold risk of breast …

View Full Text


  • Contributors KP and MK have contributed to this paper by drafting and revising this article. They have both aproved the final version of the manuscript

  • Funding KP has a fellowship from the Instituto Carlos III (PFIS/550306370), Madrid, Spain.

  • Competing interests None.

  • Provenance and peer review Commissioned; internally peer reviewed.

Linked Articles