title: Serum estrogen levels and prostate cancer risk in the prostate cancer prevention trial: a nested case-control study.
abstract: OBJECTIVE
  Finasteride reduces prostate cancer risk by blocking the conversion of testosterone to dihydrotestosterone. However, whether finasteride affects estrogens levels or change in estrogens affects prostate cancer risk is unknown.
  
  
  METHODS
  These questions were investigated in a case-control study nested within the prostate cancer prevention trial (PCPT) with 1,798 biopsy-proven prostate cancer cases and 1,798 matched controls.
  
  
  RESULTS
  Among men on placebo, no relationship of serum estrogens with risk of prostate cancer was found. Among those on finasteride, those in the highest quartile of baseline estrogen levels had a moderately increased risk of Gleason score < 7 prostate cancer (for estrone, odds ratio [OR] = 1.51, 95% confidence interval [CI] = 1.06-2.15; for estradiol, OR = 1.50, 95% CI = 1.03-2.18). Finasteride treatment increased serum estrogen concentrations; however, these changes were not associated with prostate cancer risk.
  
  
  CONCLUSIONS
  Our findings confirm those from previous studies that there are no associations of serum estrogen with prostate cancer risk in untreated men. In addition, finasteride results in a modest increase in serum estrogen levels, which are not related to prostate cancer risk. Whether finasteride is less effective in men with high serum estrogens, or finasteride interacts with estrogen to increase cancer risk, is uncertain and warrants further investigation.
authors.affiliation: Department of Cancer Prevention and Control, Roswell Park Cancer Institute, Buffalo, NY, USA.
authors.forename: Song
authors.initials: S
authors.lastname: Yao
authors.forename: Cathee
authors.initials: C
authors.lastname: Till
authors.forename: Alan R
authors.initials: AR
authors.lastname: Kristal
authors.forename: Phyllis J
authors.initials: PJ
authors.lastname: Goodman
authors.forename: Ann W
authors.initials: AW
authors.lastname: Hsing
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Tangen
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Platz
authors.forename: Frank Z
authors.initials: FZ
authors.lastname: Stanczyk
authors.forename: Juergen K V
authors.initials: JK
authors.lastname: Reichardt
authors.forename: Li
authors.initials: L
authors.lastname: Tang
authors.forename: Marian L
authors.initials: ML
authors.lastname: Neuhouser
authors.forename: Regina M
authors.initials: RM
authors.lastname: Santella
authors.forename: William D
authors.initials: WD
authors.lastname: Figg
authors.forename: Douglas K
authors.initials: DK
authors.lastname: Price
authors.forename: Howard L
authors.initials: HL
authors.lastname: Parnes
authors.forename: Scott M
authors.initials: SM
authors.lastname: Lippman
authors.forename: Ian M
authors.initials: IM
authors.lastname: Thompson
authors.forename: Christine B
authors.initials: CB
authors.lastname: Ambrosone
authors.forename: Ashraful
authors.initials: A
authors.lastname: Hoque
mesh_terms: D058891:5-alpha Reductase Inhibitors / Q000008:administration & dosage*; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D004958:Estradiol / Q000097:blood*; D004970:Estrone / Q000097:blood*; D005260:Female; D018120:Finasteride / Q000008:administration & dosage*; D006801:Humans; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D011471:Prostatic Neoplasms / Q000097:blood* / Q000473:pathology / Q000517:prevention & control*; D012307:Risk Factors
chemical_list: D058891:5-alpha Reductase Inhibitors; D004970:Estrone; D004958:Estradiol; D018120:Finasteride