title: A systematic review and meta-analysis of tobacco use and prostate cancer mortality and incidence in prospective cohort studies.
abstract: BACKGROUND
  An association between tobacco smoking and prostate cancer (PCa) incidence and mortality was suggested in an earlier meta-analysis of 24 prospective studies in which dose-response associations and risks per unit of tobacco use were not examined.
  
  
  OBJECTIVE
  We investigated the association between several measures of tobacco use and PCa mortality (primary outcome) and incidence (secondary outcome) including dose-response association.
  
  
  METHODS
  Relevant articles from prospective studies were identified by searching the PubMed and Web of Science databases (through January 21, 2014) and reference lists of relevant articles. Combined relative risks (RRs) and 95% confidence intervals (CIs) were calculated using random effects methods. We also calculated population attributable risk (PAR) for smoking and PCa mortality.
  
  
  RESULTS
  We included 51 articles in this meta-analysis (11823 PCa deaths, 50349 incident cases, and 4,082,606 cohort participants). Current cigarette smoking was associated with an increased risk of PCa death (RR: 1.24; 95% CI, 1.18-1.31), with little evidence for heterogeneity and publication bias. The number of cigarettes smoked per day had a dose-response association with PCa mortality (p=0.02; RR for 20 cigarettes per day: 1.20). The PAR for cigarette smoking and PCa deaths in the United States and Europe were 6.7% and 9.5%, respectively, corresponding to >10000 deaths/year in these two regions. Current cigarette smoking was inversely associated with incident PCa (RR: 0.90; 95% CI, 0.85-0.96), with high heterogeneity in the results. However, in studies completed in 1995 or earlier (considered as completed before the prostate-specific antigen screening era), ever smoking showed a positive association with incident PCa (RR: 1.06; 95% CI, 1.00-1.12) with little heterogeneity.
  
  
  CONCLUSIONS
  Combined evidence from observational studies shows a modest but statistically significant association between cigarette smoking and fatal PCa. Smoking appears to be a modifiable risk factor for PCa death.
  
  
  RESULTS
  Smoking increases the chance of prostate cancer death. Not smoking prevents this harm and many other tobacco-related diseases.
authors.affiliation: The Tisch Cancer Institute and Institute for Transitional Epidemiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA; Surveillance and Health Services Research, American Cancer Society, Atlanta, GA, USA; Digestive Oncology Research Center, Digestive Disease Research Institute, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Farhad
authors.initials: F
authors.lastname: Islami
authors.affiliation: The Arthur Smith Institute for Urology, North Shore Long Island Jewish Health System, New Hyde Park, NY, USA.
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Moreira
authors.affiliation: The Tisch Cancer Institute and Institute for Transitional Epidemiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
authors.forename: Paolo
authors.initials: P
authors.lastname: Boffetta
authors.affiliation: Urology Section, Veterans Affairs Medical Center, Durham, NC, USA; Division of Urology, Department of Surgery, and the Duke Prostate Center, Duke University School of Medicine, Durham, NC, USA; Department of Pathology, Duke University School of Medicine, Durham, NC, USA. Electronic address: steve.freedland@duke.edu.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Freedland
mesh_terms: D006801:Humans; D015994:Incidence; D008297:Male; D064887:Observational Studies as Topic; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000453:epidemiology / Q000401:mortality*; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects / Q000453:epidemiology*; D062789:Tobacco Products / Q000706:statistics & numerical data
keywords: Cigarettes; Meta-analysis; Prospective; Prostate cancer; Smoking