Table 4.

Circadian rhythm disruption as a risk factor for breast cancer

Risk factor	Author	Year	Type of study	Conclusion	Population
Circadian rhythm disruption	Pronk et al.28	2010	Cohort study	Epidemiological evidence did not provide consistent support for this association.	Varied
	Lie et al.29	2011	Cohort study	Significantly higher risks were observed in nurses who worked for 6 consecutive night shifts over the course of 5 years.	Nurses
	Hansen et al.30	2012	Case-control study	Further evidence that night work can increase the risk of breast cancer.	Nurses
	Ijaz et al.31	2013	Meta-analysis	Insufficient evidence for a link between night work and breast cancer.	Varied
	He et al.33	2014	Meta-analysis	Circadian disruption is associated with an increased risk of breast cancer.	Varied
	Grundy et al.34	2014	Case-control study	Significant association between the two variables in the long term.	Varied
	Åkerstedt et al.35	2015	Cohort study	Increased risk of breast cancer in women, but only after relatively long exposure.	Varied
	Li et al.36	2015	Case-control study	Non-significant association.	Textile workers
	Cordina-Duverger et al.37	2017	Meta-analysis	Night work increases the risk of breast cancer in pre-menopausal women.	Varied
	Lee et al.38	2018	Review	Associations between breast cancer and night work were reported by several epidemiological investigations, including cohort studies, case-control studies and meta-analyses. However, the dose-response relationship was not clear.	Varied