1. CANCER RISK IN CHILDREN EXPOSED TO CT SCANS Allison Low 3.10.2013

2. Clinical Question Do CT scans in children and adolescents increase their subsequent risk of developing cancer? P - children and adolescents I - CT scans C - no CT scans O - cancer

3. Clinical cases 13 year old boy with an incidental finding of papilloedema, neurological examination otherwise normal 4 year old girl, RTA, GCS of 9, visible head injury, no external abdominal injuries, haemodynamically stable

4. Current practice

6. Methods population based, cohort, data linkage study Australia 10.9 million people aged 0-19 (Medicare) over a 20 year period ending in 2005 monitoring until 2007

7. Methods Medicare records record all (funded) CT scans Australian Cancer Database (ICD-10 codes) socioeconomic status from SEIFA

8. Methods - missed scans state-based tertiary hospitals (not on records) scans outside of Australia

9. Analysis one year lag period (also five and ten year lags) IRRs exposed vs unexposed dosage: estimate by site, year of scan, age (changed after 2001)

10. Results

11. Scans in exposed patients

12. Results mean length of follow up: 17.3 years (unexposed), 9.5 years (exposed) 3150 exposed individuals developed cancer 57 524 non-exposed developed cancer overall, IRR 24% higher in exposed group (IRR 1.24, 95% CI 1.20-1.29)

13. Main results

14. Other results IRR increased with each additional CT scan (0.16, 95% CI 0.13-0.19) IRR increased for all cancers combined, also for all solid organ cancers, all lymphoid and haematopoeitic cancers site-specific eg leukaemia after CT abdo/pelvis gender difference for non-brain solid organ tumours: F>M (1.23) socioeconomic status: no significant difference

15. Brain cancer brain cancer - highest risk 1-4 years after exposure, higher risk for 15 years under five years riskiest ? reverse causation - analysis repeated excluding all brain cancers after CT brain - 1.20, 95% CI 1.15-1.24

16. CASP tool

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28. Discussion points (no trauma CT patients with subsequent leukaemia in Sheffield...) Image Gently/ALARA CT scans vs clinical skill