title: Meta-analysis of the association of dermatomyositis and polymyositis with cancer.
abstract: BACKGROUND
  Although some features of dermatomyositis (DM) and polymyositis (PM) have been reported as possible prognostic indicators for cancer development, previous studies were small in size and were unable to establish a definitive relationship between neoplasms and DM and PM.
  
  
  OBJECTIVE
  To evaluate risk factors for developing malignancies in patients with DM and PM.
  
  
  METHODS
  Meta-analysis of the studies reported in the literature was performed to unveil risk factors for developing cancer among patients with DM and PM. The included studies were either cohort or retrospective case-control studies with information on cancer status. Risk for malignancy was determined as the odds ratio (OR) or weighted mean difference (WMD) with a 95% confidence interval (CI), determined by fixed and random effects models. Stata 10.0 software was used to identify possible publication bias.
  
  
  RESULTS
  Twenty studies with 380 patients and 1575 controls were included in the analysis. The factors that may increase the risk of cancer in patients with DM and PM were older age (WMD 11·41, 95% CI 9·84-12·98), male sex (OR 1·92, 95% CI 1·49-2·48), cutaneous necrosis (OR 5·52, 95% CI 3·49-8·74) and dysphagia (OR 2·41, 95% CI 1·50-3·86), whereas those that may provide protection against cancer included arthritis (OR 0·38, 95% CI 0·24-0·61) and interstitial lung disease (OR 0·32, 95% CI 0·20-0·51).
  
  
  CONCLUSIONS
  Our data suggest that age, sex, cutaneous necrosis, dysphagia, arthritis and lung complications may influence susceptibility to cancer in patients with DM and PM.
authors.affiliation: Shanghai Children's Hospital, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: G
authors.initials: G
authors.lastname: Guo
authors.forename: G
authors.initials: G
authors.lastname: Chen
authors.forename: B
authors.initials: B
authors.lastname: Wu
authors.forename: L
authors.initials: L
authors.lastname: Lu
authors.forename: L
authors.initials: L
authors.lastname: Bao
mesh_terms: D000367:Age Factors; D016022:Case-Control Studies; D003680:Deglutition Disorders / Q000209:etiology; D003882:Dermatomyositis / Q000150:complications*; D004198:Disease Susceptibility; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009336:Necrosis; D009369:Neoplasms / Q000209:etiology*; D017285:Polymyositis / Q000150:complications*; D017594:Publication Bias; D012189:Retrospective Studies; D012307:Risk Factors; D012737:Sex Factors; D012867:Skin / Q000473:pathology