Revision 1

Accepted · first revision · record

Title: Causal cancer risk from diagnostic CT exposure
Plain: Children scanned by CT show slightly more cancers later, but sicker children get scanned more often, which could explain the association by itself.
Precise: Establish whether the excess leukaemia, haematological-cancer and brain-tumour incidence observed in paediatric CT cohorts, reported as excess relative risk of about 1 to 2.5 per 10 rad organ dose, is causal after removing reverse causation from scans prompted by the undiagnosed disease and from cancer-predisposition syndromes, and after correcting organ-dose reconstruction errors. An answer is a causal risk coefficient or a demonstration that the association is confounded.
Settled by: Cohorts with clinical indication for each scan recorded, adequate lag exclusion and individual organ-dose reconstruction.
Kind: well-posed
Answer type: yes-no
References: (empty)
Literature status: contested
Status note: EPI-CT (2023; ERR about 1.3 per 10 rad for brain cancer, about 2.0 per 10 rad for haematological malignancy) and a North American cohort of about 3.7 million children (Smith-Bindman et al., NEJM 2025; ERR about 2.5 per 10 rad for haematologic cancer) report dose-related excesses; residual confounding by indication and by cancer-predisposition syndromes is still debated.
Posed since: 2012