title: Population-based cohort study on the risk of malignancy in East Asian children with juvenile idiopathic arthritis.
abstract: BACKGROUND
  To investigate the association and magnitude of risk between JIA, its associated treatment and cancer development in Taiwanese children.
  
  
  METHODS
  Nationwide population-based 1:4 age- and gender-matched retrospective cohort study was designed using the National Health Insurance Research Database of Taiwan. A cohort of 2,892 children <16 years old with JIA was formed as well as a non-JIA cohort of 11,568 in year 2003 to 2005. They were followed up till a diagnosis of malignancy or up to 8 years until 2010. Relative risk (RR), incidence rate ratio (IRR), and adjusted hazard ratio (aHR) of developing malignancy were calculated.
  
  
  RESULTS
  The female to male ratio was 0.79:1. There were 3 cases of incident cancer in the "MTX use, biologics-naïve" group, only 1 in the anti-TNF biologics-containing group and 29 in the "both MTX- and biologics-naïve" group, in comparison, there were 50 cases of cancer in the non-JIA comparator group. During a 16114.16 patient-years follow-up, the RR and IRR for developing a malignancy in both methotrexate- and anti-tumor necrosis factor (TNF) biologics-naïve JIA children were 2.75 (95% confidence interval, 1.75 - 4.32) and 3.21 (2.01 - 5.05), respectively. For leukemia, the IRR was 7.38 (2.50 - 22.75); lymphoma, 8.30 (1.23 - 69.79); and soft tissue sarcoma, 11.07 (0.84 - 326.4). The IRR of other cancers was 2.08 (1.11 - 3.71). The aHR on cancer risk was 3.14 (1.98 - 4.98) in methotrexate- and biologics-naïve group. There were no statistically significant increased risk in JIA patients treated with methotrexate and/or anti-TNF biologics.
  
  
  CONCLUSIONS
  Compared with children without JIA, children with JIA have 3-fold increase of risk on malignancy in East Asia. Seemingly neither methotrexate nor anti-TNF biologics increases the risk further.
authors.forename: Victor C
authors.initials: VC
authors.lastname: Kok
authors.affiliation: Population-Health and Clinical Informatics Research Group, Department of Biomedical Informatics, Asia University Taiwan, Taichung, Taiwan. horng@db.csie.ncu.edu.tw.
authors.forename: Jorng-Tzong
authors.initials: JT
authors.lastname: Horng
authors.forename: Jing-Long
authors.initials: JL
authors.lastname: Huang
authors.forename: Kuo-Wei
authors.initials: KW
authors.lastname: Yeh
authors.forename: Jia-Jing
authors.initials: JJ
authors.lastname: Gau
authors.forename: Cheng-Wei
authors.initials: CW
authors.lastname: Chang
authors.forename: Lai-Zhen
authors.initials: LZ
authors.lastname: Zhuang
mesh_terms: D000293:Adolescent; D001171:Arthritis, Juvenile / Q000188:drug therapy* / Q000453:epidemiology; D001688:Biological Products / Q000009:adverse effects* / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D005202:Asia, Eastern / Q000453:epidemiology; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008727:Methotrexate / Q000009:adverse effects* / Q000627:therapeutic use; D009369:Neoplasms / Q000139:chemically induced / Q000453:epidemiology*; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors*
chemical_list: D001688:Biological Products; D014409:Tumor Necrosis Factor-alpha; D008727:Methotrexate