title: Association between sex hormones and colorectal cancer risk in men and women.
abstract: OBJECTIVE
  There is observational and clinical evidence that indicates that sex hormones affect development of colorectal cancer in men and women. However, the relationship between endogenous sex hormone levels and colorectal cancer is unclear.
  
  
  METHODS
  We collected data on lifestyle, medical history, and diet (through 2008), along with blood samples, from the Nurses' Health Study, the Women's Health Study, the Health Professional Follow-up Study, and the Physicians' Health Study II. We measured plasma levels of estrone, estradiol, testosterone, sex hormone binding globulin (SHBG), and C-peptide among 730 women (293 cases of colorectal cancer and 437 healthy individuals as controls) and 1158 men (439 colorectal cancer cases and 719 controls) and used unconditional logistic regression to estimate relative risks (RRs) and 95% confidence intervals. All statistical tests were 2-sided.
  
  
  RESULTS
  Total testosterone, SHBG, and the ratio of estradiol to testosterone were associated with colorectal cancer in men after adjustments for matching and risk factors for colorectal cancer, including body mass index and plasma levels of C-peptide. The RRs in the highest relative to the lowest quartile were 0.62 for testosterone (95% confidence interval, 0.40-0.96), 0.65 for SHBG (95% confidence interval, 0.42-0.99), and 2.63 for the ratio (95% confidence interval, 1.58-4.36) (P values for trend ≤ .02). However, in women, only the ratio of estradiol to testosterone was (inversely) associated with colorectal cancer after adjustments for all factors (RR, 0.43; 95% confidence interval, 0.22-0.84; P value for trend = .03).
  
  
  CONCLUSIONS
  On the basis of combined data from 4 population studies, there appears to be an association between levels of sex hormones and colorectal cancer risk in men. There also appears to be an inverse association between the ratio of estradiol to testosterone and colorectal cancer in postmenopausal women.
authors.affiliation: Division of Preventive Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02215, USA. jhlin@rics.bwh.harvard.edu
authors.forename: Jennifer H
authors.initials: JH
authors.lastname: Lin
authors.forename: Shumin M
authors.initials: SM
authors.lastname: Zhang
authors.forename: Kathryn M
authors.initials: KM
authors.lastname: Rexrode
authors.forename: Joann E
authors.initials: JE
authors.lastname: Manson
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Chan
authors.forename: Kana
authors.initials: K
authors.lastname: Wu
authors.forename: Shelley S
authors.initials: SS
authors.lastname: Tworoger
authors.forename: Susan E
authors.initials: SE
authors.lastname: Hankinson
authors.forename: Charles
authors.initials: C
authors.lastname: Fuchs
authors.forename: J Michael
authors.initials: JM
authors.lastname: Gaziano
authors.forename: Julie E
authors.initials: JE
authors.lastname: Buring
authors.forename: Edward
authors.initials: E
authors.lastname: Giovannucci
mesh_terms: D000368:Aged; D002096:C-Peptide / Q000097:blood; D015179:Colorectal Neoplasms / Q000453:epidemiology*; D005260:Female; D012739:Gonadal Steroid Hormones / Q000097:blood*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018570:Risk Assessment; D012738:Sex Hormone-Binding Globulin / Q000032:analysis
chemical_list: D002096:C-Peptide; D012739:Gonadal Steroid Hormones; D012738:Sex Hormone-Binding Globulin