title: Head and neck cancer among marijuana users: a meta-analysis of matched case-control studies.
abstract: OBJECTIVE
  The scientific literature presents conflicting data on a possible causal relationship between marijuana users and the development of head and neck cancer.
  
  
  METHODS
  This study performed a systematic review with meta-analysis. Articles were selected from various electronic databases using keywords obtained from the Medical Subject Headings (MeSH). After reading by three reviewers and scoring of methodological quality, six articles (totaling nine case-control studies) were assessed with Comprehensive Meta-Analysis(®) software. The value of effect (odds ratio) was calculated, which represented the chance of developing head and neck cancer between individuals who had smoked marijuana in their lifetime in models controlled for age, gender, race, and tobacco consumption.
  
  
  RESULTS
  Approximately 12.6% of cases and 14.3% of controls were marijuana users. The meta-analysis found no association between exposure and disease (OR=1.021; IC 95%=0.912-1.14; p=0.718).
  
  
  CONCLUSIONS
  No association between lifetime marijuana use and the development of head and neck cancer was found. The different methods of collection/presentation of results in the selected articles prevented other analyzes from being conducted. Additional studies are needed to assess for long-term effects.
authors.affiliation: Graduate Program in Dentistry Faculty of Sciences of Health, Federal University of Minas Gerais - UFMG, Av. Pres. Antônio Carlos, 6627 - Campus Pampulha CEP: 31.270-901, Belo Horizonte, MG, Brazil. Electronic address: monize_c@hotmail.com.
authors.forename: M F F
authors.initials: MF
authors.lastname: de Carvalho
authors.affiliation: Graduate Program in Oral Pathology, Piracicaba Dental School, University of Campinas - Unicamp, Av. Limeira, 901 - Vila Rezende, Piracicaba, SP 13414-903, Brazil. Electronic address: mauricio_mrd@hotmail.com.
authors.forename: M R
authors.initials: MR
authors.lastname: Dourado
authors.affiliation: Graduate Program in Dentistry, Faculty of Sciences of Health, Federal University of Jequitinhonha and Mucuri Valleys - UFVJM, Rua da Glória, 187, Bairro Centro, CEP: 39.100-000, Diamantina, MG, Brazil. Electronic address: bellahfernandes@hotmail.com.
authors.forename: I B
authors.initials: IB
authors.lastname: Fernandes
authors.affiliation: Department of Dentistry, Faculty of Sciences of Health, Federal University of Jequitinhonha and Mucuri Valleys - UFVJM, Rua da Glória, 187, Bairro Centro, CEP: 39.100-000, Diamantina, MG, Brazil. Electronic address: ctpimenta@gmail.com.
authors.forename: C T P
authors.initials: CT
authors.lastname: Araújo
authors.affiliation: Department of Dentistry, Faculty of Sciences of Health, Federal University of Jequitinhonha and Mucuri Valleys - UFVJM, Rua da Glória, 187, Bairro Centro, CEP: 39.100-000, Diamantina, MG, Brazil. Electronic address: hanamesquita@hotmail.com.
authors.forename: A T
authors.initials: AT
authors.lastname: Mesquita
authors.affiliation: Department of Dentistry, Faculty of Sciences of Health, Federal University of Jequitinhonha and Mucuri Valleys - UFVJM, Rua da Glória, 187, Bairro Centro, CEP: 39.100-000, Diamantina, MG, Brazil. Electronic address: mlramosjorge@gmail.com.
authors.forename: M L
authors.initials: ML
authors.lastname: Ramos-Jorge
mesh_terms: D016022:Case-Control Studies; D006258:Head and Neck Neoplasms / Q000453:epidemiology*; D006801:Humans; D008385:Marijuana Smoking; D012307:Risk Factors
keywords: Cannabis sativa; Case–control; Head and neck cancer; Meta-analysis