A related commentary discusses this research. These results provide the impetus for the thyroid cancer community to design and implement prospective, randomised clinical trials specifically designed to assess the efficacy and optimal administered activity of ¹³¹I when used as adjuvant treatment. To that end, selection of patients for adjuvant treatment trials should be based not only on initial risk stratification eligibility based on estimates of the risk of recurrence or disease-specific mortality) but also on careful evaluation of disease status following appropriate initial surgery so that we can differentiate the potential role of ¹³¹I therapy for the treatment of known persistent disease from that of true adjuvant treatment.