In 2007, based on good evidence from mouse studies and limited evidence from epidemiological studies, IARC declared that shift work involving night work was a probable carcinogen (mainly regarding breast cancer). Since then, several studies on shift work and breast cancer have been released, which are less supportive of the association. In the epidemiological literature, the dominant hypothesis regarding the underlying mechanism for the association is that light at night suppresses melatonin, resulting in a diminution of the anti-carcinogenic effects.
In this talk, Lin Fritschi, cancer epidemiologist and head of the Epidemiology Group at the Western Australian Institute for Medical Research in Perth, will outline the framework that includes an additional four possible mechanisms. This framework has been used to design a questionnaire that can disentangle various aspects of shift work, in order to determine which of the mechanisms are most related to any effect. Fritschi's group is using this questionnaire in a current case-control study of breast cancer.