title: Male circumcision and penile cancer: a systematic review and meta-analysis.
abstract: OBJECTIVE
  We systematically reviewed the evidence of an association between male circumcision and penile cancer.
  
  
  METHODS
  Databases were searched using keywords and text terms for the epidemiology of penile cancer. Random effects meta-analyses were used to calculate summary odds ratios (ORs) and 95% confidence intervals (CI).
  
  
  RESULTS
  We identified eight papers which evaluated the association of circumcision with penile cancer, of which seven were case-control studies. There was a strong protective effect of childhood/adolescent circumcision on invasive penile cancer (OR = 0.33; 95% CI 0.13-0.83; 3 studies). In two studies, the protective effect of childhood/adolescent circumcision on invasive cancer no longer persisted when analyses were restricted to boys with no history of phimosis. In contrast, there was some evidence that circumcision in adulthood was associated with an increased risk of invasive penile cancer (summary OR = 2.71; 95% CI 0.93-7.94; 3 studies). There was little evidence for an association of penile intra-epithelial neoplasia and in situ penile cancer with circumcision performed at any age.
  
  
  CONCLUSIONS
  Men circumcised in childhood/adolescence are at substantially reduced risk of invasive penile cancer, and this effect could be mediated partly through an effect on phimosis. Expansion of circumcision services in sub-Saharan Africa as an HIV prevention strategy may additionally reduce penile cancer risk.
authors.affiliation: MRC Tropical Epidemiology Group, Department of Infectious Disease Epidemiology, Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. Natasha.larke@lshtm.ac.uk
authors.forename: Natasha L
authors.initials: NL
authors.lastname: Larke
authors.forename: Sara L
authors.initials: SL
authors.lastname: Thomas
authors.forename: Isabel
authors.initials: I
authors.lastname: dos Santos Silva
authors.forename: Helen A
authors.initials: HA
authors.lastname: Weiss
mesh_terms: D016022:Case-Control Studies; D002944:Circumcision, Male / Q000009:adverse effects / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D010412:Penile Neoplasms / Q000453:epidemiology* / Q000209:etiology; D012307:Risk Factors