Dietary and Environmental Exposure to Cadmium and the Risk of Breast Cancer.

摘要

This study examined whether exposure to cadmium (Cd) from dietary or environmental sources increases the risk of breast cancer. We examined this hypothesis using information collected from the California Teachers Study (CTS) cohort, a group of approximately 130,000 female school employees living in California followed for breast cancer since 1995. Information collected by questionnaire included residential addresses, exposure to tobacco smoke, and food and beverage consumption. We assessed levels of dietary and environmental exposure by linking these collected data with available information on Cd residue levels in foods and beverages and environmental sources of Cd pollution near women s residences. In addition, we used existing urine samples provided by a subset of 296 women in the CTS to identify predictors of urinary Cd concentrations, which is considered a good measure of cumulative lifetime exposure. In this analysis, estimates of dietary Cd intake and environmental Cd exposure were not associated with urinary Cd concentrations and we observed only modest agreement between repeat measurements of urinary Cd concentrations in the exposure sub-study. We then evaluated whether dietary and environmental exposure to Cd increased the risks of estrogen-receptor (ER) subtypes of breast cancer in the entire CTS cohort. We observed an increased risk for ER-negative breast cancer associated with residential proximity to high vehicular traffic density and with residence in a census tract with an elevated Cd concentration in ambient air. We observed a modest increase in risk for ER-positive breast cancer, particularly among women with larger body size (BMI 30 kg/m2). We failed to observe an association between dietary Cd intake and breast cancer risk. This final report summarizes the work conducted over the entire research period.