Résumé :
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[BDSP. Notice produite par INIST-CNRS sm9R0x7r. Diffusion soumise à autorisation]. Recent studies suggest that vitamin D may be associated with reduced breast cancer risk, but most studies have evaluated only dietary vitamin D intake. The associations among ultraviolet radiation from sunlight, factors related to cutaneous vitamin D production, and breast cancer risk were evaluated in a population-based case-control study conducted in Ontario, Canada, between 2003 and 2004 (n=3,101 cases and n=3,471 controls). Time spent outdoors was associated with reduced breast cancer risk during 4 periods of life (>21 vs.<6 hours/week age-adjusted odds ratio (OR)=0.71,95% confidence interval (CI) : 0.60,0.85 in the teenage years ; OR=0.64,95% CI : 0.53,0.76 in the 20s-30s ; OR=0.74,95% CI : 0.61,0.88 in the 40s-50s ; and OR=0.50,95% CI : 0.37,0.66 in the 60s-74 years). Sun protection practices and ultraviolet radiation were not associated with breast cancer risk. A combined solar vitamin D score, including all the variables related to vitamin D production, was significantly associated with reduced breast cancer risk. These associations were not confounded or modified by menopausal status, dietary vitamin D intake, or physical activity. This study suggests that factors suggestive of increased cutaneous production of vitamin D are associated with reduced breast cancer risk.
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