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Malignancy incidence in 5294 patients with juvenile arthritis
  1. Omid Zahedi Niaki1,
  2. Ann E Clarke2,
  3. Rosalind Ramsey-Goldman3,
  4. Rae Yeung4,
  5. Kristen Hayward5,
  6. Kiem Oen6,
  7. Ciarán M Duffy7,
  8. Alan Rosenberg8,
  9. Kathleen M O'Neil9,
  10. Emily von Scheven10,
  11. Laura Schanberg11,
  12. Jeremy Labrecque1,
  13. Shirley M L Tse4,
  14. Rachana Hasija4,
  15. Jennifer L F Lee1 and
  16. Sasha Bernatsky1,12
  1. 1Department of Medicine, McGill University, Montreal, Quebec, Canada
  2. 2Department of Medicine, University of Calgary, Calgary, Alberta, Canada
  3. 3Northwestern University, Feinberg School of Medicine, Chicago, Illinois, USA
  4. 4Division of Rheumatology, The Hospital for Sick Children, Toronto, Ontario, Canada
  5. 5Department of Rheumatology, Seattle Children's Hospital, Seattle, Washington, USA
  6. 6Department of Pediatrics, University of Manitoba, Winnipeg, Manitoba, Canada
  7. 7Department of Pediatrics, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
  8. 8Department of Pediatrics, Royal University Hospital, Saskatoon, Saskatchewan, Canada
  9. 9Division of Pediatric Rheumatology, Riley Hospital for Children, Indianapolis, Indiana, USA
  10. 10Department of Pediatric Rheum San Francisco, University of California, San Francisco, California, USA
  11. 11Department of Pediatrics, Duke University Medical Center, Durham, North Carolina, USA
  12. 12Division of Clinical Epidemiology, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
  1. Correspondence to Dr Sasha Bernatsky; Sasha.bernatsky{at}mcgill.ca

Abstract

Objective To determine cancer incidence in a large clinical juvenile-onset arthritis population.

Methods We combined data from 6 existing North American juvenile-onset arthritis cohorts. Patients with juvenile-onset arthritis were linked to regional cancer registries to detect incident cancers after cohort entry, defined as first date seen in the paediatric rheumatology clinic. The expected number of malignancies was obtained by multiplying the person-years observed (defined from cohort entry to end of follow-up) by the geographically matched age, sex and calendar year-specific cancer rates. The standardised incidence ratios (SIR; ratio of cancers observed to expected) were generated, with 95% CIs.

Results The 6 juvenile arthritis registries provided a total of 5294 patients. The mean age at cohort entry was 8.9 (SD 5.0) years and 68% of participants were female. The mean duration of follow-up was 6.8 years with a total of 36 063 person-years spanning 1978–2012. During follow-up, 9 invasive cancers occurred, compared with 10.9 expected (SIR 0.82, 95% CI 0.38 to 1.5). 3 of these were haematological (Hodgkin's, non-Hodgkin's lymphoma and leukaemia). 6 of the patients with cancer were exposed to disease-modifying drugs; 5 of these had also been exposed to biological agents.

Conclusions We did not clearly demonstrate an increase in overall malignancy risk in patients with juvenile-onset arthritis followed for an average of almost 7 years. 3 of the 9 observed cancers were haematological. 5 of the cancers arose in children exposed to biological agents. Longer follow-up of this population is warranted, with further study of drug effects.

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  • Received November 16, 2015.
  • Revision received March 8, 2016.
  • Accepted March 9, 2016.
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