Prevalence of thyroid malignancy and hormonal dysfunction following radiation exposure in childhood

Introduction: Childhood radiation exposure is a known risk factor for thyroid malignancy and dysfunction. However, local data are limited and there is no consensus on the modality and frequency of screening in this high-risk group. Methods: Retrospective analysis study evaluating patients with childhood radiation exposure in 2006-2016 and minimum of 1-year follow-up. Results: Of the 132 childhood cancer survivors in the study, thyroid malignancy was detected in 2 cases (1.5%) and thyroid nodules in 13 (9.8%). The earliest thyroid malignancy was detected 5 years post-radiotherapy via ultrasound. Of the 84 patients who had screening thyroid function test, 26 (31.0%) were detected with abnormal test results post-radiation, majority being subclinical hypothyroidism. Conclusion: Regular screening via clinical examination for thyroid nodules should be performed at least annually. Where feasible and if resources permit, consideration should be given to using ultrasound for thyroid nodule(s) and malignancy screening at 5 years post-radiation therapy. Screening for thyroid dysfunction can be considered from 6-12 months post-radiotherapy.