title: What is the impact of chronic systemic inflammation such as rheumatoid arthritis on mortality following cancer?
abstract: BACKGROUND
  Emerging evidence links inflammation and immune competence to cancer progression and outcome. Few studies addressing cancer survival in the context of rheumatoid arthritis (RA) have reported reduced survival without accounting for the underlying mortality risk in RA. Whether this increased mortality is a cancer-specific phenomenon, an effect of the decreased lifespan in RA or a combination of both remains unknown.
  
  
  METHODS
  Using Swedish register data (2001-2009), we performed a cohort study of individuals with RA (N=34 930), matched to general population comparators (N=169 740), incident cancers (N=12 676) and deaths (N=14 291). Using stratified Cox models, we estimated HRs of death associated with RA in the presence and absence of cancer, by stage and time since cancer diagnosis, for all cancers and specific sites.
  
  
  RESULTS
  In the absence of cancer, RA was associated with a doubled mortality rate (HR=2.1, 95% CI 2.0 to 2.2). In the presence of cancer, the relative effect of RA on mortality was varied by stage. For cancer (tumour, node, metastases) stages I and II at diagnosis, the relative effect of RA on mortality was the same as in the absence of cancer. For cancers diagnosed at advanced stages with absolute higher mortality, the effect decreased (HR=1.2, 95% CI 1.1 to 1.3). These associations remained across time since cancer diagnosis and were reasonably similar across cancer sites.
  
  
  CONCLUSIONS
  Much of the increase in mortality in patients with RA diagnosed with cancer seems to reside with effects of RA independently of the cancer.
authors.affiliation: Clinical Epidemiology Unit, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden Division of Epidemiology, Department of Health Research & Policy, Stanford School of Medicine, Stockholm, Sweden.
authors.forename: J F
authors.initials: JF
authors.lastname: Simard
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
authors.forename: S
authors.initials: S
authors.lastname: Ekberg
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
authors.forename: A L V
authors.initials: AL
authors.lastname: Johansson
authors.affiliation: Clinical Epidemiology Unit, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden Department of Rheumatology, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Askling
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000150:complications / Q000401:mortality*; D002908:Chronic Disease; D015897:Comorbidity; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D009369:Neoplasms / Q000209:etiology / Q000401:mortality* / Q000473:pathology; D012042:Registries; D013548:Sweden / Q000453:epidemiology
keywords: Epidemiology; Outcomes research; Rheumatoid Arthritis