title: Oxychlordane and trans-nonachlor in breast adipose tissue and risk of female breast cancer.
abstract: BACKGROUND
  Organochlorine compounds, including organochlorine pesticides, have been suggested by some, but not all, studies to be associated with female breast-cancer risk. So far, studies relating organochlorine compounds and breast-cancer risk have mainly focused on polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDT) as risk factors for female breast cancer. This paper examines the hypothesis that environmental exposure to trans-nonachlor (TNC) and oxychlordane (OCD), a major metabolite of the insecticide chlordane, increases the
  
  
  METHODS
  A total of 304 histologically confirmed, incident primary breast-cancer patients and 186 histologically confirmed incident benign breast-disease controls were included in the study between 1994 and 1997. Breast adipose tissue not needed for diagnostic purposes was collected and analysed for TNC, OCD and other organochlorine compounds. A standardised, structured questionnaire was used to obtain information on major known, or suspected, risk factors for breast cancer.
  
  
  RESULTS
  The age and lipid-adjusted geometric mean adipose-tissue levels of OCD were similar between the cases [36.4 p.p.b., 95% confidence interval (CI) 34.7-38.2 p.p.b.] and controls (38.0 p.p.b., 95% Cl 35.7-40.6 p.p.b.). The age and lipid-adjusted geometric mean adipose-tissue levels of TNC between the cases (55.5 p.p.b., 95% CI 52.6-58.5 p.p.b.) and controls (58.1 p.p.b., 95% CI 54.2-62.3 p.p.b.) were also similar. There was no association between breast-cancer risk and mean adipose-tissue levels of OCD and TNC. The covariate-adjusted odds ratio (OR) was 0.7 (95% CI 0.4-1.3) for OCD and 1.1 (95% CI 0.6-1.9) for TNC, when the highest quartile was compared with the lowest. The risk also did not vary based on oestrogen or progesterone receptor status or menopausal status.
  
  
  CONCLUSIONS
  We found no significantly increased risk of breast cancer associated with breast adipose-tissue levels of OCD or TNC; this is consistent with recent epidemiological studies, indicating that environmental exposure to organochlorine compounds does not have an overall significant impact on breast-cancer risk.
authors.affiliation: Yale University School of Medicine and Yale Cancer Center, New Haven, USA.
authors.forename: T
authors.initials: T
authors.lastname: Zheng
authors.forename: T R
authors.initials: TR
authors.lastname: Holford
authors.forename: J
authors.initials: J
authors.lastname: Tessari
authors.forename: S T
authors.initials: ST
authors.lastname: Mayne
authors.forename: S H
authors.initials: SH
authors.lastname: Zahm
authors.forename: P H
authors.initials: PH
authors.lastname: Owens
authors.forename: B
authors.initials: B
authors.lastname: Zhang
authors.forename: B
authors.initials: B
authors.lastname: Ward
authors.forename: D
authors.initials: D
authors.lastname: Carter
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: W
authors.initials: W
authors.lastname: Zhang
authors.forename: R
authors.initials: R
authors.lastname: Dubrow
authors.forename: P
authors.initials: P
authors.lastname: Boyle
mesh_terms: D000273:Adipose Tissue / Q000737:chemistry / Q000378:metabolism*; D000328:Adult; D000368:Aged; D001940:Breast / Q000737:chemistry / Q000378:metabolism*; D001943:Breast Neoplasms / Q000139:chemically induced / Q000378:metabolism*; D016022:Case-Control Studies; D002706:Chlordan / Q000031:analogs & derivatives* / Q000032:analysis / Q000493:pharmacokinetics; D002849:Chromatography, Gas / Q000379:methods / Q000706:statistics & numerical data; D005260:Female; D006533:Heptachlor / Q000032:analysis / Q000493:pharmacokinetics*; D006801:Humans; D007306:Insecticides / Q000032:analysis / Q000493:pharmacokinetics*; D016015:Logistic Models; D008875:Middle Aged; D012307:Risk Factors
chemical_list: D007306:Insecticides; D002706:Chlordan; C008743:oxychlordane; D006533:Heptachlor