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Increased incidence of squamous cell carcinoma of the skin after long-term treatment with azathioprine in patients with auto-immune inflammatory rheumatic diseases

Authors


  • Conflicts of interest
    The other authors declare no conflicts of interest for this article. J.M.P.A. van den Reek carries out clinical trials for Abbott and Janssen and has received reimbursement for attending a symposium from Janssen. P.P.M. van Lümig carries out clinical trials for Abbott and Janssen. P.P.M. van Lümig has received speaking and consulting fees from Wyeth and Schering-Plough and has received reimbursement for attending a symposium from Janssen, Schering-Plough and Pfizer. P.C.M. van de Kerkhof serves as a consultant for Schering-Plough, Celgene, Centocor, Allmirall, UCB, Wyeth, Pfizer, Sofinnova, Abbott, Actelion, Galderma, Novartis, Janssen-Cilag and LEO Pharma. P.C.M. van de Kerkhof receives research grants from Centocor, Wyeth, Schering-Plough, Merck Serono, Abbott and Philips Lighting. M.M.B. Seyger has served as a consultant for Wyeth, Pfizer and Abbott, and received grants from Wyeth, Pfizer and LeoPharma. E.M.G.J. de Jong served as a consultant for Biogen, Merck Serono, Wyeth and Abbott. E.M.G.J. de Jong has received research grants from or was involved in clinical trials from Schering-Plough, Abbott, Merck Serono, Wyeth, Centocor and Janssen-Cilag.

  • Funding sources
    This was an investigator initiated study. The Radboud University Nijmegen Medical Centre was supported in part by UMC St Radboud Foundation, who received funding from Pfizer and Abbott for the project. Pfizer and Abbott played no role in the design and conduct of the study, data collection, data management, data analysis, interpretation of the data, manuscript preparation, manuscript review or manuscript approval.

Abstract

Background  Auto-immune inflammatory rheumatic diseases (AIRD) are often successfully treated with the immunosuppressant azathioprine for years. Treatment with azathioprine has been proven to increase the risk of non-melanoma skin cancer (NMSC) in transplant patients and possibly in patients with inflammatory bowel disease as well. Little is known about the risk of NMSC in AIRD patients treated with azathioprine.

Objectives  The aim of this study is to determine the incidence of NMSC in patients with AIRD treated with azathioprine for at least 1 year, as compared with the general Dutch population.

Methods  Data were extracted from a historical cohort of patients with AIRD in a tertiary care centre. We compared the incidence to an age-matched control population and analysed risk factors for NMSC with univariate logistic regression.

Results  Fifty-nine patients were analysed. No patients were diagnosed with basal cell carcinoma and four patients with a single squamous cell carcinoma (SCC). Patients with SCC had a higher cumulative dose of azathioprine (≥500 g: OR 30.0 [95% CI 2.6–345.1]) and longer treatment duration (≥11 years: OR 13.5 [95% CI 1.3–143.6]). The risk of SCC compared with the general Dutch population was increased (standardized incidence ratio of 16.0 [95% CI 0.3–31.7]).

Conclusions  In this cohort of patients with AIRD treated with azathioprine for at least 1 year, the risk of SCC was increased, as compared with the general population. An individual cumulative dose of at least 500 g azathioprine and a treatment duration of at least 11 years were quantified as risk factors.

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