Prednisone-aided gross thyroid remnant ablation using 5.55 GBq of radioiodine in patients with differentiated thyroid cancer.

Background: Radioiodine ( 131 I) remnant ablation (RRA) with activities ranging from 1.1-3.7 GBq showed dismal efficacy but a dose-effect relationship in patients with differentiated thyroid cancer (DTC) after less-than-total thyroidectomy.

Methods: A prospective study was conducted in patients with DTC with gross thyroid remnants. All subjects received an activity of 5.55 GBq of 131 I in combination with a 1-week course of prednisone at a dose of 60 mg/day. The primary endpoints included success rate and safety; secondary endpoints included changes in 131 I uptake value, gross thyroid remnant volume, serum thyroglobulin levels, and levothyroxine replacement dose.

Results: Forty-two patients were eligible for analyses with a median follow-up of 35 months. The ablation success rate reached 95.2%, with all grade 1 adverse events. The incidence of long-term (11.9%) adverse events was significantly lower than intermediate (28.6%) and immediate (69.0%) ones. The most frequent treatment-related immediate adverse events included neck pain (54.8%), weakness (30.1%), neck swelling (23.8%), stomachache (21.4%), palpitation (16.7%), and nausea (9.5%). After RRA, the median 24-h 131 I uptake value and the thyroid remnant volume decreased significantly ( P  < 0.05). The thyrotropin-stimulated thyroglobulin level dropped remarkably (20.54 ± 21.58 vs. 1.54 ± 3.21 mIU/L; P  < 0.05), becoming undetectable in 11 (28.9%) patients; While the dose of administered levothyroxine enhanced notably ( P  = 0.033).

Conclusion: Our data demonstrated that prednisone-aided RRA utilizing a single dose of 5.55 GBq of 131 I achieved a high success rate of 95.2% and an excellent safety profile in patients with DTC with gross thyroid remnant.