title: Androgens, growth factors, and risk of prostate cancer: the Multiethnic Cohort.
abstract: BACKGROUND
  Androgens and growth factors are thought to be associated with prostate cancer risk, although past research has produced mixed results.
  
  
  METHODS
  We conducted a nested case-control study of biomarkers of prostate cancer risk within the Multiethnic Cohort. We compared prediagnostic levels of testosterone, dihydrotestosterone (DHT), sex hormone-binding globulin (SHBG), 3alpha-androstanediol glucuronide (3alpha-diol G), insulin-like growth factor I (IGF-I), IGF-II, IGF-binding protein 1 (IGFBP-1), and IGFBP-3 in serum from 467 incident prostate cancer cases and 934 cancer-free controls. Controls were matched to the cases on geographic site (HI, LA), ethnicity, age at specimen collection (+/-1 year), date (+/-1 month) and time of day (+/-2 hr) of sample collection, and fasting status (<6, 6-7, 8-9, >10 hr). Multivariate conditional logistic regression models were used to compute adjusted odds ratios (ORs) and 95% confidence intervals (CIs).
  
  
  RESULTS
  Serum concentrations of testosterone, DHT, SHBG, 3alpha-diol G, IGF-I, IGF-II, IGFBP-1, and IGFBP-3 were not associated with risk of prostate cancer. Tests for trend of quartiles of serum concentrations also did not show any association. Results were relatively unchanged for men with advanced prostate cancer and their matched controls. However, the follow-up period was relatively short (mean of 1.9 years). Analysis by ethnic group showed an increased risk for Latino men in the second (OR = 3.67, 95% CI: 1.63-8.24) and third (OR = 2.96, 95% CI: 1.19-7.40) tertiles of IGF-I serum levels compared with the first tertile.
  
  
  CONCLUSIONS
  The suggested increased risk for IGF-I in Latino men merits further study, with greater statistical power.
authors.affiliation: Department of Health Science, California State University, Fullerton, CA, USA. jasmeetgill@fullerton.edu
authors.forename: Jasmeet K
authors.initials: JK
authors.lastname: Gill
authors.forename: Lynne R
authors.initials: LR
authors.lastname: Wilkens
authors.forename: Michael N
authors.initials: MN
authors.lastname: Pollak
authors.forename: Frank Z
authors.initials: FZ
authors.lastname: Stanczyk
authors.forename: Laurence N
authors.initials: LN
authors.lastname: Kolonel
mesh_terms: D000368:Aged; D000728:Androgens / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007335:Insulin-Like Growth Factor II / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D011471:Prostatic Neoplasms / Q000097:blood* / Q000208:ethnology; D011863:Radioimmunoassay; D012044:Regression Analysis; D018570:Risk Assessment; D012307:Risk Factors; D011795:Surveys and Questionnaires
chemical_list: D000728:Androgens; D015415:Biomarkers; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II