title: Risk for lung cancer in workers exposed to benzidine and/or beta-naphthylamine: a protocol for systematic review and meta-analysis.
abstract: BACKGROUND
  Risk for lung cancer in workers exposed to benzidine (BZ) and/or beta-naphthylamine (BNA), which are well-known bladder carcinogens, has been examined in many epidemiological studies, but individual epidemiological studies generally lack the power to examine the association between BZ/BNA exposure and lung cancer. We conduct a systematic review and meta-analysis to determine the risk for lung cancer among workers exposed to BZ/BNA occupationally.
  
  
  METHODS
  Studies will be identified by a MEDLINE, EMBASE, CDSR, and CINAHL search and by the reference lists of articles/relevant reviews. Eligible studies will be cohort and case-control studies that report occupational BZ/BNA exposure and the outcome of interest (lung cancer death/incidence). The method of meta-analysis will be used to combine standardized mortality ratios (SMRs) and/or standardized incidence ratios (SIRs) from retrospective and prospective cohort studies and odds ratios (ORs) from case-control studies. Two reviewers will independently screen articles, extract data, and assess scientific quality using standardized forms and published quality assessment tools tailored for each study design. Overall pooled risk estimates and their corresponding 95% confidence intervals (CIs) will be obtained using random effects model. This systematic review and meta-analysis will be conducted following the Meta-analysis of Observational Studies in Epidemiology (MOOSE) guidelines, and results will be reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement.
  
  
  CONCLUSIONS
  This review will identify and synthesize studies of the association between occupational BZ/BNA exposure and lung cancer. The findings will help to identify whether BZ/BNA could cause lung cancer and might indicate whether workers with exposure to BZ/BNA have a need for preventive measures against non-urological cancer besides bladder cancer.
  
  
  BACKGROUND
  PROSPERO CRD42014010250.
authors.affiliation: Department of Community Health and Epidemiology, Nara Medical University, Shijo-cho 840, Kashihara City, Nara 634-8521, Japan. tkimiko@naramed-u.ac.jp.
authors.forename: Kimiko
authors.initials: K
authors.lastname: Tomioka
authors.forename: Keigo
authors.initials: K
authors.lastname: Saeki
authors.forename: Kenji
authors.initials: K
authors.lastname: Obayashi
authors.forename: Yuu
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Norio
authors.initials: N
authors.lastname: Kurumatani
mesh_terms: D015081:2-Naphthylamine / Q000633:toxicity*; D001560:Benzidines / Q000633:toxicity*; D002617:Chemical Industry; D006801:Humans; D015994:Incidence; D008175:Lung Neoplasms / Q000453:epidemiology*; D016273:Occupational Exposure / Q000009:adverse effects*; D012107:Research Design; D012307:Risk Factors; D012408:Rubber; D000078202:Systematic Reviews as Topic; D015201:Meta-Analysis as Topic
chemical_list: D001560:Benzidines; C029876:benzidine; D012408:Rubber; D015081:2-Naphthylamine