title: Comparison of estrogens and estrogen metabolites in human breast tissue and urine.
abstract: BACKGROUND
  An important aspect of the link between estrogen and breast cancer is whether urinary estrogen levels are representative of the intra-tissue levels of bioavailable estrogens.
  
  
  METHODS
  This study compares 15 estrogen and estrogen metabolite levels in breast tissue and urine of 9 women with primary breast cancer using a quantitative liquid chromatography-mass spectrometry method.
  
  
  RESULTS
  The average levels of estrogens (estrone, 17 beta-estradiol) were significantly higher in breast tissue than in urine. Both the 2 and the 16-hydroxylation pathways were less represented in breast tissue than urine; no components of the 4-hydroxypathway were detected in breast tissue, while 4-hydroxyestrone was measured in urine. However, the 2/16 ratio was similar in urine and breast tissue. Women carrying the variant CYP1B1 genotype (Leu/Val and Val/Val) showed significantly lower overall estrogen metabolite, estrogen, and 16-hydroxylation pathway levels in breast tissue in comparison to women carrying the wild type genotype. No effect of the CYP1B1 polymorphism was observed in urinary metabolites.
  
  
  CONCLUSIONS
  The urinary 2/16 ratio seems a good approximation of the ratio observed in breast tissue. Metabolic genes may have an important role in the estrogen metabolism locally in tissues where the gene is expressed, a role that is not readily observable when urinary measurements are performed.
authors.affiliation: SUNY Downstate Medical Center, Brooklyn, New York 11203, USA. emanuela.taioli@downstate.edu
authors.forename: Emanuela
authors.initials: E
authors.lastname: Taioli
authors.forename: Annie
authors.initials: A
authors.lastname: Im
authors.forename: Xia
authors.initials: X
authors.lastname: Xu
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Veenstra
authors.forename: Gretchen
authors.initials: G
authors.lastname: Ahrendt
authors.forename: Seymour
authors.initials: S
authors.lastname: Garte
mesh_terms: D000328:Adult; D000368:Aged; D001189:Aryl Hydrocarbon Hydroxylases; D001940:Breast / Q000378:metabolism* / Q000473:pathology; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000652:urine; D018270:Carcinoma, Ductal, Breast / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000652:urine; D016022:Case-Control Studies; D065633:Cytochrome P-450 CYP1B1; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism; D004958:Estradiol / Q000378:metabolism* / Q000652:urine*; D004967:Estrogens / Q000378:metabolism* / Q000652:urine*; D005260:Female; D005787:Gene Frequency; D006801:Humans; D007930:Leucine / Q000235:genetics; D053858:Metabolic Networks and Pathways / Q000235:genetics / Q000502:physiology; D055442:Metabolome; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide / Q000502:physiology; D014633:Valine / Q000235:genetics
chemical_list: D004967:Estrogens; D004958:Estradiol; D003577:Cytochrome P-450 Enzyme System; D001189:Aryl Hydrocarbon Hydroxylases; C585496:CYP1B1 protein, human; D065633:Cytochrome P-450 CYP1B1; D007930:Leucine; D014633:Valine