O10-1 Occupational exposure to extremely low frequency magnetic fields and risk of breast cancer in the mcc-spain study

Background Exposure to extremely low frequency magnetic fields (ELF-MF) is a suspected risk factor for leukaemia in children and possibly for brain tumours in adults. Though early studies suggested an association between ELF-MF and breast cancer, recent meta-analyses have been contradictory and, while some reported positive associations, in particular in post-menopausal women, others reported no evidence of an association. In this study, we examined the association between occupational ELF-MF and breast cancer risk in the MCC-Spain study using a recently updated version of an ELF-MF job-exposure matrix (JEM). Methods A total of 1,539 female breast cancer cases and 1,602 controls, recruited throughout ten Spanish regions between 2008 and 2013, were included in this analysis. Estimates of lifetime cumulative exposure to ELF-MF were assigned to study participants based on the ELF-JEM, recoded to the Spanish system of occupations (CNO94, four digits), and information collected on the subjects9 occupational histories. An analysis was performed using unconditional logistic regression adjusted for age, education, and region. Results A statistically significant positive association was observed for lifetime cumulative ELF-MF exposure, Odds Ratio (OR) per 10 unit log-transformed geometric mean = 1.10; 95% confidence interval (CI), 1.01–1.20; p = 0.027). Analyses including reproductive and hormonal factors as well as using average exposure and exposure in different time windows will be presented. Conclusions Occupational exposure to ELF-MF may play a role in breast cancer risk.