title: Estimated dietary dioxin exposure and breast cancer risk among women from the French E3N prospective cohort.
abstract: BACKGROUND
  Dioxins are environmental and persistent pollutants mostly emitted from combustion facilities (e.g. waste incinerators, metal and cement industries). Known to be endocrine disrupting chemicals, dioxins are suspected to increase breast cancer (BC) risk. Although diet is considered the primary source of dioxin exposure, no previous study has been published on dietary dioxin exposure in relation to BC risk. We aimed to assess dietary dioxin exposure among women from the E3N cohort and estimate BC risk associated with this exposure.
  
  
  METHODS
  The study included 63,830 women from the E3N cohort who completed a diet history questionnaire (DHQ) in 1993 and were followed until 2008. Dietary dioxin exposure was estimated by combining consumption data from the E3N DHQ and food dioxin contamination data from a French national monitoring program. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated by Cox models adjusted for BC risk factors.
  
  
  RESULTS
  Mean dietary dioxin exposure was estimated at 1.3 ± 0.4 pg/kg body weight (BW)/day. A 0.4 pg/kg BW/d increase in dioxin intake was not associated with overall BC risk (HR = 1.00; 95% CI: 0.96, 1.05). A significant decrease in risk of estrogen receptor negative (ER-)/progesterone receptor negative (PR-) tumors was observed among post-menopausal women in the upper quartile of estimated dioxin intake (HR for Q4 vs. Q1: 0.65; 95% CI: 0.45, 0.96; P for trend across quartiles = 0.0463).
  
  
  CONCLUSIONS
  Overall, no association between estimated dietary dioxin exposure and BC risk was found among E3N women. Further studies should include both dietary and environmental exposures to determine whether low-dose dioxin exposure is associated with BC risk.
authors: Aurélie M N
authors: AM
authors: Danjou
authors: Béatrice
authors: B
authors: Fervers
authors: Marie-Christine
authors: MC
authors: Boutron-Ruault
authors: Thierry
authors: T
authors: Philip
authors: Françoise
authors: F
authors: Clavel-Chapelon
authors: Laure
authors: L
authors: Dossus
mesh_terms: D001943:Breast Neoplasms / Q000453:epidemiology* / Q000209:etiology* / Q000473:pathology; D004032:Diet / Q000009:adverse effects*; D004147:Dioxins / Q000009:adverse effects*; D005260:Female; D005500:Follow-Up Studies; D005506:Food Contamination; D005602:France / Q000453:epidemiology; D006801:Humans; D008875:Middle Aged; D011159:Population Surveillance; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012306:Risk; D011795:Surveys and Questionnaires
chemical_list: D004147:Dioxins