title: ω-3 and ω-6 Polyunsaturated fatty acid intakes and the risk of breast cancer in Mexican women: impact of obesity status.
abstract: BACKGROUND
  ω-3 polyunsaturated fatty acids (PUFA) could play a protective role on the risk of breast cancer; however, little is known about this relation among Mexican women. We evaluated the association between ω-3 and ω-6 PUFA intake and breast cancer risk by obesity status in Mexican women.
  
  
  METHODS
  A population-based case-control study was conducted in Mexico, including 1,000 incident breast cancer cases and 1,074 controls matched to cases by age, health care system, and region. Women provided information on health and diet by in-person interview. Body mass index (BMI) measures were used to define overall obesity. Obesity status was categorized as normal weight (18.5 < BMI < 25), overweight (25 ≤ BMI < 30), and obese (BMI ≥ 30). A conditional logistic regression model was used to assess the association between PUFA and breast cancer risk.
  
  
  RESULTS
  Overall, there was no significant association between ω-3 PUFA intake and breast cancer risk (P = 0.31). An increased risk of breast cancer was associated with increasing ω-6 PUFA intake in premenopausal women [OR = 1.92, 95% confidence interval (CI) = 1.13-3.26; P = 0.04]. A decreased risk of breast cancer was significantly associated with increasing ω-3 PUFA intake in obese women (OR = 0.58, 95% CI = 0.39-0.87; P = 0.008) but not in normal weight nor in overweight women (P(heterogeneity) = 0.017).
  
  
  CONCLUSIONS
  Obesity status may affect the association between ω-3 PUFA intake and breast cancer risk. The underlying mechanisms may be related to decreased inflammation and improved adipokin and estrogen levels induced by ω-3 PUFA in adipose tissue in obese women.
  
  
  CONCLUSIONS
  Increased intake of ω-3 PUFA should be recommended among Mexican women in particular in obese women.
authors.affiliation: Nutrition and Metabolism, International Agency for Research on Cancer, 150, cours Albert Thomas, 69372 Lyon cedex 08, France.
authors.forename: Véronique
authors.initials: V
authors.lastname: Chajès
authors.forename: Gabriela
authors.initials: G
authors.lastname: Torres-Mejía
authors.forename: Carine
authors.initials: C
authors.lastname: Biessy
authors.forename: Carolina
authors.initials: C
authors.lastname: Ortega-Olvera
authors.forename: Angélica
authors.initials: A
authors.lastname: Angeles-Llerenas
authors.forename: Pietro
authors.initials: P
authors.lastname: Ferrari
authors.forename: Eduardo
authors.initials: E
authors.lastname: Lazcano-Ponce
authors.forename: Isabelle
authors.initials: I
authors.lastname: Romieu
mesh_terms: D001943:Breast Neoplasms / Q000453:epidemiology*; D016022:Case-Control Studies; D015525:Fatty Acids, Omega-3 / Q000008:administration & dosage*; D043371:Fatty Acids, Omega-6 / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D008800:Mexico / Q000453:epidemiology; D008875:Middle Aged; D009765:Obesity / Q000453:epidemiology*; D012307:Risk Factors
chemical_list: D015525:Fatty Acids, Omega-3; D043371:Fatty Acids, Omega-6