Thyroid cancer post radioactive iodine treatment for hyperthyroidism - case series and review of the literature.

INTRODUCTION: To assess the rate of thyroid cancer and mortality rate in a cohort of patients who received RAI¹³¹ treatment for hyperthyroidism and to report the index cases' characteristics and management MATERIAL AND METHODS: A cohort of 264 patients who received RAI¹³¹ treatment for different causes of thyrotoxicosis were followed up over a period of 18 years (1996-2014) by physical exam, radiological evaluation and serial thyroid function tests.

RESULTS: During the follow up period, three cases of thyroid cancer were identified. The prevalence of thyroid cancer was 1.136% of cases who received RAI¹³¹. The relative risk was 378.79 (95% CI: 76.8 < RR < 1868.23). The P value was < 0.0000004 and the SMR is 1.99/1000.

CONCLUSIONS: The prevalence of thyroid cancer was 1.136% in the cohort of patients treated with RAI¹³¹. Despite the fact that no direct cause-effect relationship between RAI and thyroid cancer could be established, these cases highlights the importance of life-long surveillance of patients who receive RAI¹³¹.