Clinical outcomes of patients with T4 or N1b well-differentiated thyroid cancer after different strategies of adjuvant radioiodine therapy.

We aimed to determine whether recombinant human thyrotropin (rhTSH) plus 3.7 GBq could replace thyroid hormone withdrawal (THW) plus 5.55 GBq for adjuvant radioactive iodine (RAI) therapy in differentiated thyroid cancer (DTC) patients with T4 or N1b disease. This study was a retrospective study comparing ablation success rate, response to initial therapy, and recurrence-free survival (RFS) of patients with rhTSH plus 3.7 GBq versus those with THW plus 5.55 GBq in 253 DTC patients with T4 or N1b disease. There were no differences in the TSH-stimulated thyroglobulin level, rate of incomplete response after initial treatment, or the RFS between the two treatment strategies. However, thyroid bed uptake on follow-up diagnostic RAI whole-body scanning (WBS) was more frequently observed in the group treated with rhTSH plus 3.7 GBq than in the group with THW plus 5.55 GBq. Adjuvant RAI therapy with rhTSH plus 3.7 GBq had comparable results in the absence of persistent tumor, compared with that with THW plus 5.55 GBq. Although thyroid bed uptake was more frequently observed, rhTSH plus 3.7 GBq may be used instead of THW plus 5.55 GBq for adjuvant RAI therapy in patients with T4 or N1b disease.