title: Urinary estrogen metabolites and breast cancer: differential pattern of risk found with pre- versus post-treatment collection.
abstract: BACKGROUND
  The products of estrogen metabolism may affect breast carcinogenesis. The 16alpha-hydroxyestrone (16-OHE) metabolite has a higher affinity for the estrogen receptor (ER) than the 2-hydroxyestrone (2-OHE) metabolite, while conjugated 2-OHE metabolite may inhibit angiogenesis. We investigated the association between the relative concentrations of these metabolites in urine (2-OHE/16-OHE) and breast cancer in a case-control study of Chinese women living in Shanghai.
  
  
  METHODS
  Incident breast cancer cases between 25 and 65 years of age (n=110) were identified from hospital or population tumor registries in Shanghai, China. Controls (n=110) were randomly selected from a complete registry of the Shanghai population, and individually matched to cases by menopausal status, age, and pre-treatment or post-treatment urine collection time. Urine samples were collected prior to any breast cancer treatment or surgery among 78 case-control pairs, while urine was collected after surgery, and perhaps other treatments, among 32 case-control pairs. A commercial enzyme-immunoassay kit was used to measure urinary estrogen metabolite concentrations. Conditional logistic regression was used to calculate odds ratios summarizing the 2-OHE/16-OHE and breast cancer association within subjects providing either pre-treatment or post-treatment urine samples.
  
  
  RESULTS
  Subjects with a higher urinary 2-OHE/16-OHE ratio were less likely to be diagnosed with breast cancer, but only when urine samples were collected prior to breast cancer treatment (OR(Tertile3(T3)versusTertile1(T1))=0.5, 95% CI (0.2, 1.1)). In contrast, a higher 2-OHE/16-OHE ratio was significantly associated with breast cancer among subjects providing urine specimens after treatment initiation (OR(T3versusT1)=8.7, 95% CI (1.6, 47.1)). This observed cross-over modification occurred within both pre-menopausal and post-menopausal women, and independent of body mass index or recent dietary intake.
  
  
  CONCLUSIONS
  Cross-study differences in urine collection protocols may explain observed inconsistencies in the 2-OHE/16-OHE and breast cancer association. Our case-control analysis using pre-treatment urine samples suggested that a lower 2-OHE/16-OHE ratio was associated with an increased risk of pre-menopausal and post-menopausal breast cancer diagnosis among Chinese women.
authors.affiliation: Vanderbilt University Medical Center, Nashville, TN 37232-8300, USA. jay.fowke@vanderbilt.edu
authors.forename: Jay H
authors.initials: JH
authors.lastname: Fowke
authors.forename: Dai
authors.initials: D
authors.lastname: Qi
authors.forename: H Leon
authors.initials: HL
authors.lastname: Bradlow
authors.forename: Xiao Ou
authors.initials: XO
authors.lastname: Shu
authors.forename: Yu Tang
authors.initials: YT
authors.lastname: Gao
authors.forename: Jin Rong
authors.initials: JR
authors.lastname: Cheng
authors.forename: Fan
authors.initials: F
authors.lastname: Jin
authors.forename: Wei
authors.initials: W
authors.lastname: Zheng
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000175:diagnosis / Q000628:therapy / Q000652:urine*; D016022:Case-Control Studies; D002681:China; D004967:Estrogens / Q000378:metabolism / Q000652:urine*; D005260:Female; D006801:Humans; D006894:Hydroxyestrones / Q000652:urine; D008875:Middle Aged; D016017:Odds Ratio; D017698:Postmenopause / Q000652:urine; D017697:Premenopause / Q000652:urine; D012307:Risk Factors
chemical_list: D004967:Estrogens; D006894:Hydroxyestrones; C026702:16-hydroxyestrone