title: Sexual activity and prostate cancer risk in men diagnosed at a younger age.
abstract: OBJECTIVE
  To examine, in a case-control study, the association between the frequency of sexual activity (intercourse, masturbation, overall) and prostate cancer risk in younger men diagnosed at < or = 60 years old.
  
  
  METHODS
  In all, 431 prostate cancer cases and 409 controls participated and provided information on their sexual activity. In particular, the frequencies of intercourse and masturbation during the participants' different age decades (20s, 30s, 40s, 50s) were collected.
  
  
  RESULTS
  Whereas frequent overall sexual activity in younger life (20s) increased the disease risk, it appeared to be protective against the disease when older (50s). Alone, frequent masturbation activity was a marker for increased risk in the 20s and 30s but appeared to be associated with a decreased risk in the 50s, while intercourse activity alone was not associated with the disease.
  
  
  CONCLUSIONS
  These findings could imply different mechanisms by which sexual activity is involved in the aetiology of prostate cancer at different ages. Alternatively, there is a possibility of reverse causation in explaining part of the protective effect seen for men in their 50s.
authors.affiliation: University of Nottingham Medical School, Queens Medical Centre, Nottingham, UK. pd317@medschl.cam.ac.uk
authors.forename: Polyxeni
authors.initials: P
authors.lastname: Dimitropoulou
authors.forename: Artitaya
authors.initials: A
authors.lastname: Lophatananon
authors.forename: Douglas
authors.initials: D
authors.lastname: Easton
authors.forename: Richard
authors.initials: R
authors.lastname: Pocock
authors.forename: David P
authors.initials: DP
authors.lastname: Dearnaley
authors.forename: Michelle
authors.initials: M
authors.lastname: Guy
authors.forename: Steven
authors.initials: S
authors.lastname: Edwards
authors.forename: Lynne
authors.initials: L
authors.lastname: O'Brien
authors.forename: Amanda
authors.initials: A
authors.lastname: Hall
authors.forename: Rosemary
authors.initials: R
authors.lastname: Wilkinson
authors.forename: Rosalind
authors.initials: R
authors.lastname: Eeles
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Muir
mesh_terms: D000328:Adult; D000367:Age Factors; D016022:Case-Control Studies; D003075:Coitus; D006801:Humans; D008297:Male; D008418:Masturbation / Q000150:complications*; D008875:Middle Aged; D015999:Multivariate Analysis; D011471:Prostatic Neoplasms / Q000209:etiology*; D012307:Risk Factors; D055815:Young Adult