Use of radioactive iodine in children and young adults with differentiated thyroid cancer significantly increases the risk of future haematologic and solid malignancies, research confirms.

Although the treatment is already linked to a greater risk of leukaemia 2-3 years post-exposure, the findings suggest the need for long-term surveillance of these patients, the US authors say.

Drawing on data from nine cancer registries, the team quantified the probability of second primary malignancies associated with radioactive iodine (RAI) treatment in children and young adults with differentiated thyroid cancer (DTC) across four decades.

Among 27,000 five-year survivors with a median 15 years’ follow-up, RAI was associated with a 23% increased risk of solid malignancies, namely uterine and renal cancers.