title: Red and processed meat consumption and risk of bladder cancer: a dose-response meta-analysis of epidemiological studies.
abstract: OBJECTIVE
  Several epidemiological studies have analyzed the associations between red and processed meat and bladder cancer risk but the shape and strength of the associations are still unclear. Therefore, we conducted a dose-response meta-analysis to quantify the potential association between red and processed meat and bladder cancer risk.
  
  
  METHODS
  Relevant studies were identified by searching the PubMed database through January 2016 and reviewing the reference lists of the retrieved articles. Results were combined using random-effects models.
  
  
  RESULTS
  Five cohort studies with 3262 cases and 1,038,787 participants and 8 cases-control studies with 7009 cases and 27,240 participants met the inclusion criteria. Red meat was linearly associated with bladder cancer risk in case-control studies, with a pooled RR of 1.51 (95% confidence interval (CI) 1.13, 2.02) for every 100 g increase per day, while no association was observed among cohort studies (P heterogeneity across study design = 0.02). Based on both case-control and cohort studies, the pooled relative risk (RR) for every 50 g increase of processed meat per day was 1.20 (95% CI 1.06, 1.37) (P heterogeneity across study design = 0.22).
  
  
  CONCLUSIONS
  This meta-analysis suggests that processed meat may be positively associated with bladder cancer risk. A positive association between red meat and risk of bladder cancer was observed only in case-control studies, while no association was observe in prospective studies.
authors.affiliation: Public Health Sciences, Karolinska Institutet, Tomtebodavagen 18A, 171 77, Stockholm, Sweden. alessio.crippa@ki.se.
authors.forename: Alessio
authors.initials: A
authors.lastname: Crippa
authors.affiliation: Unit of Nutritional Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Nobels Vag 13, 171 77, Stockholm, Sweden.
authors.forename: Susanna C
authors.initials: SC
authors.lastname: Larsson
authors.affiliation: Unit of Biostatistics, Institute of Environmental Medicine, Karolinska Institutet, Nobels Vag 13, 171 77, Stockholm, Sweden.
authors.forename: Andrea
authors.initials: A
authors.lastname: Discacciati
authors.affiliation: Unit of Nutritional Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Nobels Vag 13, 171 77, Stockholm, Sweden.
authors.forename: Alicja
authors.initials: A
authors.lastname: Wolk
authors.affiliation: Public Health Sciences, Karolinska Institutet, Tomtebodavagen 18A, 171 77, Stockholm, Sweden.
authors.forename: Nicola
authors.initials: N
authors.lastname: Orsini
mesh_terms: D000818:Animals; D002417:Cattle; D004032:Diet / Q000009:adverse effects*; D019317:Evidence-Based Medicine; D057141:Food, Preserved / Q000009:adverse effects*; D006801:Humans; D015994:Incidence; D008460:Meat / Q000009:adverse effects*; D008461:Meat Products / Q000009:adverse effects*; D015203:Reproducibility of Results; D012307:Risk Factors; D034561:Sheep, Domestic; D034421:Sus scrofa; D001749:Urinary Bladder Neoplasms / Q000453:epidemiology / Q000209:etiology*
keywords: Bladder cancer; Dose–response; Meta-analysis; Processed meat; Red meat