title: History of chronic inflammatory disorders increases the risk of Merkel cell carcinoma, but does not correlate with Merkel cell polyomavirus infection.
abstract: BACKGROUND
  We aimed to assess the connection between chronic inflammatory disorders (CIDs) and Merkel cell carcinoma (MCC).
  
  
  METHODS
  Merkel cell carcinoma cases diagnosed in 1978-2009 were extracted from the Finnish Cancer Registry and controls from the Population Registry. Information on reimbursed CIDs was linked to clinicopathological data including Merkel cell polyomavirus (MCV) status by qPCR and immunohistochemistry for the large T antigen of MCV (LTA), Ki-67 and tumour-infiltrating lymphocytes.
  
  
  RESULTS
  Chronic inflammatory disorders increased the risk of MCC significantly (odds ratio (OR) 1.39, 95% confidence interval (CI) 1.03-1.88), specifically connective tissue/systemic diseases (OR 1.75, 95% CI 1.09-1.80) and diabetic conditions (OR 1.51, 95% CI 1.03-2.22). Chronic inflammatory disorders associated with larger tumour diameter (P=0.02) and higher Ki-67 expression (P=0.005). The expression of LTA was seen significantly more often in the absence of CIDs (P=0.05).
  
  
  CONCLUSIONS
  Patients with CID are at significantly higher risk for aggressive MCC. Merkel cell polyomavirus positivity is more common in MCC patients unafflicted by CID.
authors.affiliation: Department of Dermatology and Allergology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
authors.forename: Helka
authors.initials: H
authors.lastname: Sahi
authors.affiliation: Laboratory of Molecular Oncology and Translational Cancer Biology Research Program, University of Helsinki, Helsinki, Finland.
authors.forename: Harri
authors.initials: H
authors.lastname: Sihto
authors.affiliation: Finnish Cancer Registry, Institute for Statistical and Epidemiological Cancer Research, Helsinki, Finland.|School of Health Sciences, University of Tampere, Tampere, Finland.
authors.forename: Miia
authors.initials: M
authors.lastname: Artama
authors.affiliation: Department of Plastic Surgery, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
authors.forename: Virve
authors.initials: V
authors.lastname: Koljonen
authors.affiliation: Department of Pathology, University of Helsinki and HUSLAB, Helsinki, Finland.
authors.forename: Tom
authors.initials: T
authors.lastname: Böhling
authors.affiliation: Finnish Cancer Registry, Institute for Statistical and Epidemiological Cancer Research, Helsinki, Finland.|School of Health Sciences, University of Tampere, Tampere, Finland.
authors.forename: Eero
authors.initials: E
authors.lastname: Pukkala
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015266:Carcinoma, Merkel Cell / Q000453:epidemiology* / Q000821:virology; D016022:Case-Control Studies; D002908:Chronic Disease; D004279:DNA, Viral / Q000032:analysis; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D007249:Inflammation / Q000150:complications / Q000453:epidemiology*; D008297:Male; D059965:Merkel cell polyomavirus / Q000235:genetics / Q000302:isolation & purification; D008875:Middle Aged; D027601:Polyomavirus Infections / Q000453:epidemiology* / Q000821:virology; D012042:Registries; D012307:Risk Factors; D012878:Skin Neoplasms / Q000453:epidemiology* / Q000821:virology; D014412:Tumor Virus Infections / Q000453:epidemiology* / Q000821:virology
chemical_list: D004279:DNA, Viral