title: Estrogen receptor expression in benign breast epithelium and breast cancer risk.
abstract: BACKGROUND
  Estrogen exposure is a major risk factor for breast cancer. Increased estrogen responsiveness of breast epithelium may enhance this effect. We examined the relationship between breast cancer diagnosis and 1) the presence and absence of estrogen receptor expression in benign breast epithelium, 2) the level of expression and 3) its variation during the menstrual cycle, and 4) other established risk factors. e.g., age, age at menarche, parity, and family history.
  
  
  METHODS
  We measured estrogen receptor expression (as % of positive cells) by immunohistochemistry in normal breast epithelium from 376 women undergoing diagnostic or therapeutic breast surgery. Data on established risk factors were collected prior to surgery and those on menstrual cycle dates at the time of surgery. Logistic regression was used to assess risks (odds ratios [ORs]).
  
  
  RESULTS
  The crude OR for breast cancer in women with estrogen receptor-positive breast epithelium versus those without was 3.16 (95% confidence interval [CI] = 1.89-5.28), with an OR of 2.49 (95% CI = 1.25-4.96) for premenopausal and an OR of 3.32 (95% CI = 1.43-7.68) for postmenopausal women. The ORs remained high and statistically significant after controlling for age and other breast cancer risk factors. The level of estrogen receptor expression was higher in patients with breast cancer than in control subjects and it was related to breast cancer risk in postmenopausal women (P trend <.005). Expression declined as expected in premenopausal control subjects as the menstrual cycle progressed but rose in breast cancer patients (P trend <.015).
  
  
  CONCLUSIONS
  The overexpression of estrogen receptors in normal breast epithelium may augment estrogen sensitivity and hence the risk of breast cancer.
authors.affiliation: Department of Surgery, State University of New York Health Science Center, Syracuse 13210, USA. khans@mailbox.hscsyr.edu
authors.forename: S A
authors.initials: SA
authors.lastname: Khan
authors.forename: M A
authors.initials: MA
authors.lastname: Rogers
authors.forename: K K
authors.initials: KK
authors.lastname: Khurana
authors.forename: M M
authors.initials: MM
authors.lastname: Meguid
authors.forename: P J
authors.initials: PJ
authors.lastname: Numann
mesh_terms: D000328:Adult; D001940:Breast / Q000378:metabolism*; D001943:Breast Neoplasms / Q000209:etiology / Q000378:metabolism* / Q000503:physiopathology; D016022:Case-Control Studies; D004848:Epithelium / Q000378:metabolism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D008597:Menstrual Cycle; D008875:Middle Aged; D016017:Odds Ratio; D015995:Prevalence; D011960:Receptors, Estrogen / Q000378:metabolism*; D012306:Risk; D012307:Risk Factors
chemical_list: D011960:Receptors, Estrogen