title: The serum estradiol concentration is the main determinant of the estradiol concentration in normal breast tissue.
abstract: BACKGROUND
  The estrogen concentration has been determined in breast tissue, focusing largely on samples obtained from breast cancers. In this study, estradiol concentration was determined in normal breast tissue obtained from women undergoing esthetic, and oncoplastic surgery.
  
  
  METHODS
  Normal breast tissue was obtained during 68 operations for esthetic or reconstructive indications in women with and without a history of breast cancer. Our study included six different groups of women. The first three groups were normal cycling women, women taking oral contraceptives, and normal postmenopausal women, all undergoing a bilateral esthetic breast reduction. The second three groups were premenopausal and postmenopausal women, with a history of breast cancer and currently taking tamoxifen treatment, or postmenopausal women currently taking an aromatase inhibitor, needing contra-lateral corrective esthetic surgery.
  
  
  RESULTS
  In the group of women without history of breast cancer, normal cycling women (n=24) presented a strong correlation (r=0.853; P<0.0001) between 17β-estradiol concentration in serum (median: 29.7 pg/mL; IQR: 10.8-82.3 pg/mL) and in breast tissue (30.6 pg/g; IQR: 18.6-183.8 pg/g). Postmenopausal women had low 17β-estradiol concentrations both in serum and breast tissue (r=0.813; P<0.0001, n=16). Women taking oral contraceptives (n=12) had low serum and breast tissue levels of estradiol (r=0.376; P=n.s.). Premenopausal women (n=6, mean age: 44.2 years) with a history of breast cancer and currently taking tamoxifen, had very high concentrations of 17β-estradiol both in serum (277.9 pg/mL; IQR: 96.2-544.7 pg/mL) and in epithelial cells (251.9 pg/g; IQR: 115.0-426.5 pg/g) (r=0.803; P<0.001). Postmenopausal women taking tamoxifen (n=4, mean age: 48.3) had low concentrations of 17β-estradiol in serum (7.0 pg/mL; IQR: 5.7-16.3 pg/mL) and in epithelial cells (14.6 pg/g IQR: 13.3-16.3 pg/g) (r=0.10; P=n.s.). The estradiol concentration in the breast of premenopausal women taking tamoxifen was 8.2 times higher that observed in the breast of normal cycling women, and 17.3 times higher that observed in postmenopausal women taking tamoxifen. Women taking adjuvant aromatase inhibitors had extremely low concentrations of 17β-estradiol both in serum and in breast tissue.
  
  
  CONCLUSIONS
  This study shows that serum estradiol levels largely determine estrogen levels in normal breast tissue.
authors.affiliation: Breast and Menopause Clinic, University Hospital, De Pintelaan 185, 9000 Gent, Belgium. Electronic address: herman.depypere@ugent.be.
authors.forename: H T
authors.initials: HT
authors.lastname: Depypere
authors.affiliation: Laboratory for Bioinformatics and Computational Genomics, Faculty of Bioscience Engineering, Ghent University, UGent, Coupure Links 653, 9000 Gent, Belgium.
authors.forename: S
authors.initials: S
authors.lastname: Bolca
authors.affiliation: Department of Experimental Cancer Research, University Hospital, De Pintelaan 185, 9000 Gent, Belgium.
authors.forename: M
authors.initials: M
authors.lastname: Bracke
authors.affiliation: Department of Clinical Chemistry, University Hospital, De Pintelaan 185, 9000 Gent, Belgium.
authors.forename: J
authors.initials: J
authors.lastname: Delanghe
authors.affiliation: Department of Endocrinology, University Hospital, De Pintelaan, 185, 9000 Gent, Belgium.
authors.forename: F
authors.initials: F
authors.lastname: Comhaire
authors.affiliation: Department of Esthetic and Reconstructive Surgery, University Hospital, De Pintelaan 185, 9000 Gent, Belgium.
authors.forename: Ph
authors.initials: P
authors.lastname: Blondeel
mesh_terms: D000293:Adolescent; D000328:Adult; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use; D047072:Aromatase Inhibitors / Q000627:therapeutic use; D001940:Breast / Q000737:chemistry*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000601:surgery; D003276:Contraceptives, Oral; D004958:Estradiol / Q000032:analysis* / Q000097:blood; D005260:Female; D006801:Humans; D008875:Middle Aged; D017698:Postmenopause / Q000097:blood; D017697:Premenopause / Q000097:blood; D013629:Tamoxifen / Q000627:therapeutic use; D055815:Young Adult
chemical_list: D018931:Antineoplastic Agents, Hormonal; D047072:Aromatase Inhibitors; D003276:Contraceptives, Oral; D013629:Tamoxifen; D004958:Estradiol
keywords: Aromatase inhibitor; Breast epithelium; Estradiol concentration; Tamoxifen