title: Idiopathic inflammatory myopathy associated with malignancy: a retrospective cohort of 151 Korean patients with dermatomyositis and polymyositis.
abstract: OBJECTIVE
  To define the standardized incidence ratio (SIR) of malignancy and factors associated with malignancies in Korean patients with dermatomyositis (DM) and polymyositis (PM).
  
  
  METHODS
  The demographic, clinical, and laboratory features of 151 patients diagnosed with DM/PM were compared in patients with and without malignancies.
  
  
  RESULTS
  Malignancies were found in 23 of 98 patients with DM (23.5%) and in 2 of 53 with PM (3.8%). Lung cancer (8 patients) was the most common malignancy. Compared with the period-specific, sex-matched, and age-matched Korean population, the SIR for malignancy in patients with DM was 14.2 (95% CI 9.0-21.3). Univariate analysis showed that factors associated with malignancy included older age (p < 0.001), DM (p = 0.002), dysphagia (p < 0.001), the absence of interstitial lung disease (ILD; p = 0.001), and lower elevations in aspartate aminotransferase (p = 0.005) and lactate dehydrogenase concentrations (p < 0.001). Multivariate analysis showed that factors independently associated with malignancy included older age (per 10 years, OR 2.3, 95% CI 1.6-3.5, p < 0.001), DM (OR 5.9, 95% CI 1.3-26.2, p = 0.020), dysphagia (OR 2.6, 95% CI 1.2-6.6, p = 0.042), and the absence of ILD (OR 0.1, 95% CI 0.01-0.9, p = 0.040).
  
  
  CONCLUSIONS
  DM was associated with a greater risk of concomitant malignancies, especially lung cancer, than PM. Independent factors associated with malignancies in patients with DM/PM were older age, the presence of dysphagia, and the absence of ILD.
authors.affiliation: Division of Rheumatology, Department of Internal Medicine, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Min Wook
authors.initials: MW
authors.lastname: So
authors.forename: Bon San
authors.initials: BS
authors.lastname: Koo
authors.forename: Yong-Gil
authors.initials: YG
authors.lastname: Kim
authors.forename: Chang-Keun
authors.initials: CK
authors.lastname: Lee
authors.forename: Bin
authors.initials: B
authors.lastname: Yoo
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D016022:Case-Control Studies; D015331:Cohort Studies; D015897:Comorbidity; D003680:Deglutition Disorders / Q000453:epidemiology; D003882:Dermatomyositis / Q000150:complications* / Q000453:epidemiology / Q000208:ethnology*; D005260:Female; D006801:Humans; D017563:Lung Diseases, Interstitial / Q000453:epidemiology; D008175:Lung Neoplasms / Q000453:epidemiology* / Q000208:ethnology*; D008297:Male; D008875:Middle Aged; D017285:Polymyositis / Q000150:complications* / Q000453:epidemiology / Q000208:ethnology*; D015995:Prevalence; D056910:Republic of Korea; D012189:Retrospective Studies; D012307:Risk Factors