Malignancies in juvenile idiopathic arthritis: a preliminary report.
OBJECTIVE
To present preliminary data on incidence of malignancy in juvenile idiopathic arthritis (JIA), compared to general population rates.


METHODS
We examined cancer occurrence within JIA registries at 3 Canadian pediatric rheumatology centers. The subjects in the clinic registries were linked to regional tumor registries to determine the occurrence of invasive cancers over the observation period (spanning 1974-2006). The total number of cancers expected was determined by multiplying the person-years in the cohort by age, sex, and calendar year-specific cancer rates. The standardized incidence ratio (SIR, ratio of cancers observed to expected) was generated, with 95% confidence intervals.


RESULTS
The study sample consisted of 1834 patients. The female proportion was 67.6%; average age at entry to cohort was 8.6 years (SD 5.1). The majority were Caucasian. Subjects contributed 22,341 patient-years (average 12.2, SD 7.8). Within this observation period, one invasive cancer occurred, compared to 7.9 expected (SIR 0.12, 95% CI 0.0, 0.70). This was a hematological cancer (Hodgkin's lymphoma), representing a SIR for hematological malignancies of 0.76 (95% CI 0.02, 4.21).


CONCLUSIONS
Only one invasive cancer was identified in this large sample of individuals with JIA, observed for an average of 12.2 years each. These data suggest that, at least in the initial years following diagnosis of JIA, the risk of invasive cancers overall is not markedly increased. The results do not rule out the possibility of a baseline increased risk of hematological malignancies.
McGill University Health Centre, Montreal, Canada. sasha.bernatsky@mail.mcgill.ca
Sasha
S
Bernatsky
Alan M
AM
Rosenberg
Kiem G
KG
Oen
Ciaran M
CM
Duffy
Rosalind
R
Ramsey-Goldman
Jeremy
J
Labrecque
Yvan
Y
St Pierre
Ann E
AE
Clarke
D000293:Adolescent; D018501:Antirheumatic Agents / Q000627:therapeutic use; D001171:Arthritis, Juvenile / Q000150:complications* / Q000188:drug therapy / Q000453:epidemiology*; D002170:Canada / Q000453:epidemiology; D002648:Child; D005260:Female; D006801:Humans; D009369:Neoplasms / Q000453:epidemiology* / Q000209:etiology* / Q000473:pathology; D012042:Registries; D012307:Risk Factors
D018501:Antirheumatic Agents