title: Circulating sex hormones play no role in the association between sexual activity and the risk of prostate cancer.
abstract: BACKGROUND
  High sexual activity (SA) has been reported to reduce the risk of prostate cancer (PC). The role of sex hormones (SHs) in this regard remains controversial.
  
  
  OBJECTIVE
  To determine the impact of SA and SHs on PC development.
  
  
  METHODS
  In a multicentric hospital-based case-control study, 194 newly diagnosed PC patients along with 317 age-matched controls were studied. Sociodemographic and medical characteristics of participants were recorded. History of vasectomy and sexually transmitted infection (STI), marital status, age at first intercourse, premarital sex, and the current frequency of sexual intercourses per month (SPM) were evaluated. Total testosterone (TT), free testosterone (FT), estradiol (ES), sex hormone binding globulin, and albumin were also measured. Logistic regression model was used to identify independent risk factors for PC.
  
  
  METHODS
  (i) The association between SA, SHs, and the risk of PC; (ii) The correlation between SHs and SA; (iii) The interaction between SHs and SA and established risk factors for PC and erectile dysfunction in determining the risk of PC; and (iv) The correlation between SHs and SA in determining the risk of PC in different decades of life.
  
  
  RESULTS
  Vasectomy, STI, and marital status did not differ significantly between two cohorts. Controls reported premarital sex more commonly than cases (P < 0.001). Cases had the first intercourse at older age (P = 0.03) and had less SPM (P < 0.001). TT, FT, and ES were higher in controls (P < 0.001). In multivariate analysis, TT, calculated FT, SPM >4, and age at time of marriage <24 were protective against PC. The protective effect of high SA and SHs increased as patients' age increased.
  
  
  CONCLUSIONS
  High SA as well as TT and FT were protective against PC. Their protective role enhances by each decade of increasing age. The protective effect of high SA was independent from circulating levels of SHs.
authors.affiliation: Urology Research Center, Sina Hospital, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Hamed
authors.initials: H
authors.lastname: Ahmadi
authors.forename: Farzad
authors.initials: F
authors.lastname: Allameh
authors.forename: Nima
authors.initials: N
authors.lastname: Baradaran
authors.forename: Laleh
authors.initials: L
authors.lastname: Montaser-Kouhsari
authors.forename: Shahrzad
authors.initials: S
authors.lastname: Bazargan-Hejazi
authors.forename: Sepehr
authors.initials: S
authors.lastname: Salem
authors.forename: Abdolrasoul
authors.initials: A
authors.lastname: Mehrsai
authors.forename: Gholamreza
authors.initials: G
authors.lastname: Pourmand
mesh_terms: D000367:Age Factors; D000368:Aged; D016022:Case-Control Studies; D004958:Estradiol / Q000097:blood; D012739:Gonadal Steroid Hormones / Q000097:blood*; D006801:Humans; D016015:Logistic Models; D008297:Male; D017533:Marital Status; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000097:blood / Q000209:etiology* / Q000503:physiopathology; D012307:Risk Factors; D012709:Serum Albumin / Q000032:analysis; D012738:Sex Hormone-Binding Globulin / Q000032:analysis; D012725:Sexual Behavior / Q000502:physiology*; D013739:Testosterone / Q000097:blood; D014659:Vasectomy
chemical_list: D012739:Gonadal Steroid Hormones; D012709:Serum Albumin; D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D004958:Estradiol