title: Risk factors for estrogen receptor-positive breast cancer.
abstract: OBJECTIVE
  Some risk factors associated with breast cancer may be more predictive of estrogen receptor (ER)- positive than ER-negative tumors.
  
  
  METHODS
  Survey of patients enrolled in a study of breast cancer risk factors.
  
  
  METHODS
  Community population in a northern California county.
  
  
  METHODS
  A total of 234 individuals diagnosed as having breast cancer between July 1, 1997, and June 30, 1999, reporting Marin County, California, residence and participating in a questionnaire regarding exposure to breast cancer risk factors.
  
  
  METHODS
  Diagnosis of ER-positive vs ER-negative breast cancer.
  
  
  RESULTS
  Comparison between ER-positive and ER-negative cases showed several factors predictive of ER-positive tumors. In a multivariate model, years of hormone therapy use remained the most significant predictor of ER-positive disease.
  
  
  CONCLUSIONS
  Patients diagnosed as having ER-positive breast cancer were more likely to have undergone hormone therapy. The excess of ER-positive breast cancers reported in Marin County could, therefore, in part, be related to hormone therapy.
authors.affiliation: Department of Surgery, University of California, San Francisco, Cancer Center, 94115, USA. shelley.hwang@ucsfmedctr.org
authors.forename: E Shelley
authors.initials: ES
authors.lastname: Hwang
authors.forename: Terri
authors.initials: T
authors.lastname: Chew
authors.forename: Stephen
authors.initials: S
authors.lastname: Shiboski
authors.forename: Georgianna
authors.initials: G
authors.lastname: Farren
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Benz
authors.forename: Margaret
authors.initials: M
authors.lastname: Wrensch
mesh_terms: D001943:Breast Neoplasms / Q000737:chemistry* / Q000453:epidemiology / Q000209:etiology; D002140:California / Q000453:epidemiology; D004812:Epidemiologic Methods; D005260:Female; D020249:Hormone Replacement Therapy / Q000009:adverse effects*; D006801:Humans; D008327:Mammography / Q000009:adverse effects; D008875:Middle Aged; D011960:Receptors, Estrogen; D011795:Surveys and Questionnaires; D013997:Time Factors
chemical_list: D011960:Receptors, Estrogen