Cancer in young people with Juvenile Idiopathic Arthritis (JIA) is exceedingly rare

What is it about?

What is already known? Juvenile Idiopathic Arthritis (JIA) is an auto-immune condition that starts in childhood, diagnosed in before the age of 16 years old. It affects approximately 1 or 2 in every 2’000 children and young people. Many adult-onset rheumatological conditions have been shown to increase the risk of cancer (malignancy) compared with the general population. However, there is conflicting information on whether those with JIA also have an increased risk, and most research to date have been on more historical populations of JIA who were diagnosed prior to the availability of advanced arthritis therapies. What was discovered? Using information from General Practices (GPs; primary care) in England, we identified 3’714 individuals with JIA, and 10’858 similar individuals without JIA. Those with JIA were on average 9 years old when diagnosed with JIA (or entering into the GP database), with 57% being female, 85% White, and 12% having systemic JIA. Socioeconomic position was balanced, matching the English population. For those with JIA, there was an average of over 6 years of information available following their JIA diagnosis (or entry into the GP database), and over this time, there were 19 cancers reported. This generated a malignancy rate of 6.8 per 10’000 person years. When compared to those without JIA, individuals with JIA had double the rate of malignancy. Similarly, they had higher malignancy rates that you would have expected given their age and gender when compared to the general population (information taken from the Office for National Statistics).

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Why is it important?

This research found that cancer in young people with JIA is exceedingly rare. For every 2’700 people with JIA seen each year, we identified that there would be approximately one additional cancer over and above what you would expect in this population. It is important to note that while there was a doubling risk for malignancies in individuals with JIA, the real-world risk in these individuals remains very low.