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. This evidence concerns the gene TNF and juvenile idiopathic arthritis.