title: Endogenous estrogen, androgen, and progesterone concentrations and breast cancer risk among postmenopausal women.
abstract: BACKGROUND
  Levels of endogenous hormones have been associated with the risk of breast cancer among postmenopausal women. Little research, however, has investigated the association between hormone levels and tumor receptor status or invasive versus in situ tumor status. Nor has the relation between breast cancer risk and postmenopausal progesterone levels been investigated. We prospectively investigated these relations in a case-control study nested within the Nurses' Health Study.
  
  
  METHODS
  Blood samples were prospectively collected during 1989 and 1990. Among eligible postmenopausal women, 322 cases of breast cancer (264 invasive, 41 in situ, 153 estrogen receptor [ER]-positive and progesterone receptor [PR]-positive [ER+/PR+], and 39 ER-negative and PR-negative [ER-/PR-] disease) were reported through June 30, 1998. For each case subject, two control subjects (n = 643) were matched on age and blood collection (by month and time of day). Endogenous hormone levels were measured in blood plasma. We used conditional and unconditional logistic regression analyses to assess associations and to control for established breast cancer risk factors.
  
  
  RESULTS
  We observed a statistically significant direct association between breast cancer risk and the level of both estrogens and androgens, but we did not find any (by year) statistically significant associations between this risk and the level of progesterone or sex hormone binding globulin. When we restricted the analysis to case subjects with ER+/PR+ tumors and compared the highest with the lowest fourths of plasma hormone concentration, we observed an increased risk of breast cancer associated with estradiol (relative risk [RR] = 3.3, 95% confidence interval [CI] = 2.0 to 5.4), testosterone (RR = 2.0, 95% CI = 1.2 to 3.4), androstenedione (RR = 2.5, 95% CI = 1.4 to 4.3), and dehydroepiandrosterone sulfate (RR = 2.3, 95% CI = 1.3 to 4.1). In addition, all hormones tended to be associated most strongly with in situ disease.
  
  
  CONCLUSIONS
  Circulating levels of sex steroid hormones may be most strongly associated with risk of ER+/PR+ breast tumors.
authors.affiliation: Channing Laboratory, Brigham and Women's Hospital and Harvard Medical School, 181 Longwood Avenue, Boston, MA 02115, USA. stacey.missmer@channing.harvard.edu
authors.forename: Stacey A
authors.initials: SA
authors.lastname: Missmer
authors.forename: A Heather
authors.initials: AH
authors.lastname: Eliassen
authors.forename: Robert L
authors.initials: RL
authors.lastname: Barbieri
authors.forename: Susan E
authors.initials: SE
authors.lastname: Hankinson
mesh_terms: D000368:Aged; D000728:Androgens / Q000097:blood*; D000735:Androstenedione / Q000097:blood; D001943:Breast Neoplasms / Q000097:blood* / Q000737:chemistry*; D016022:Case-Control Studies; D016001:Confidence Intervals; D003687:Dehydroepiandrosterone / Q000097:blood; D004958:Estradiol / Q000097:blood; D004967:Estrogens / Q000097:blood*; D004970:Estrone / Q000031:analogs & derivatives* / Q000097:blood; D005260:Female; D006801:Humans; D008875:Middle Aged; D017698:Postmenopause / Q000097:blood*; D011374:Progesterone / Q000097:blood*; D011960:Receptors, Estrogen / Q000032:analysis*; D011980:Receptors, Progesterone / Q000032:analysis*; D018570:Risk Assessment; D012307:Risk Factors; D013739:Testosterone / Q000097:blood
chemical_list: D000728:Androgens; D004967:Estrogens; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D004970:Estrone; D013739:Testosterone; D000735:Androstenedione; D003687:Dehydroepiandrosterone; D011374:Progesterone; D004958:Estradiol; C017296:estrone sulfate