There is limited evidence of an association between night shiftwork and breast cancer risk.
Studies showing a link between night shiftwork and a small increase in breast cancer risk have been conducted in limited groups of women – nurses and flight attendants – and appear to show an increase in risk after 20 years or more of shiftwork. However, not all studies have shown consistent results and some studies are open to questions of bias and confounding. Further research in this area is welcome.
The risk associated with nightshift work needs to reviewed in the context of other known modifiable risk factors for which there is strong evidence, such as alcohol consumption and postmenopausal weight gain.
National Breast and Ovarian Cancer Centre* awaits the publication of the International Agency for Research on Cancer’s (IARC) review of the published scientific evidence about night shiftwork and breast cancer risk so we can better assess the quality and strength of the evidence.
Please attribute this following statement to Dr Helen Zorbas, CEO National Breast and Ovarian Cancer Centre*...
Extract on night shiftwork from NBOCC’s* Breast cancer risk factors: A review of the evidence.