Is second I treatment necessary for differentiated thyroid cancer patients and who could not benefit from it? A real-world retrospective study in China.

Background: The efficacy of a second radioactive iodine-131 (I) treatment in patients with differentiated thyroid cancer (DTC) who did not achieve an excellent response (ER) following initial I therapy remains controversy and the population that would derive limited benefit from it is currently unclear.

Objectives: The aim of this retrospective study was to assess the efficacy of the second I treatment in DTC patients with non-ER after the initial I therapy, and to identify potential risk factors associated with non-benefit of the second I treatment.

Methods: 127 DTC patients who underwent two I treatments following thyroidectomy were included in this study, and the therapeutic response was evaluated after each I treatment.