Low-dose and high-dose 131I therapy for low and intermediate risk differentiated thyroid cancer: a randomized controlled clinical study

Abstract

Objective To compare the ablation efficacy and therapy response with low-dose (1.1 GBq) and high-dose (3.7 GBq) 131I in postoperative patients with low and intermediate risk DTC. Methods A total of 140 patients (37 males, 103 females, age range: 18-75 years) were enrolled from October 2014 to June 2015, and randomly assigned to low-dose group (1.1 GBq 131I) and high-dose group (3.7 GBq 131I). Diagnostic whole body scan was performed (6±3) months after radioiodine(131I, 185 MBq) therapy after L-T4 withdrawal. TSH, FT3, FT4, Tg, TgAb and neck ultrasonography were also examined. χ2 test and Fisher′s exact test were used to analyze the data. Results The data of 132 patients (33 males, 99 females, age range: 18-75 years) could be evaluated, and the half of them received low-dose radioiodine and the other half received high-dose radioiodine. Thyroid ablation was complete in 55 patients (55.6%, 55/99). The successful ablation rates in low-dose group and high-dose group were 52.7%(29/55) and 59.1%(26/44) respectively, with no significant difference (χ2=0.74, P=0.548). In the low-dose group, 80.3%(53/66) had excellent response, 19.7%(13/66) had indeterminate response, and no patients had biochemical incomplete response. In the high-dose group, the proportions were 84.8%(56/66), 10.6%(7/66) and 4.5%(3/66), respectively. There were no significant differences between the two groups (χ2=4.88, P=0.087). Conclusion The ablation efficacy and therapy response between low-dose group and high-dose group have no significant differences in postoperative patients with low and intermediate risk DTC. Key words: Thyroid neoplasms; Radiotherapy; Iodine radioisotopes; Treatment outcome