This paper presents the preliminary results of a prospective randomized trial on early effectiveness of 30 mCi versus 60 mCi for ablation of thyroid remnants in patients with WDTC after total thyroidectomy. Since April 1998 to January 2000, 220 patients with papillary thyroid cancer in stage T1b-3, N0-x, M0 had entered the study. 106 patients received 60 mCi and 114 received 30 mCi as the first ablation dose. The subject for the analysis was the uptake over the neck, post-therapeutic whole body scintigraphy and Tg level 6 months after ablation. The early effectiveness of ablation was estimated using a 5-degree scale: 0--very good effect, 1--good effect, 2--dubious effect-required repetition of WBS and Tg assessment in 6-12 months, 3--insufficient ablation--required repetition of radioiodine treatment, 4--for evident dissemination or local recurrence.
Results: Grades 0 were obtained in 29 (53%) after 30 mCi (group I) and in 38 patients (86%) after 60 mCi (group II). Grades 1 were obtained in group I in 15 patients (28%) and in 4 patients (9%) of group II. Grades 2 were obtained in group I in 9 patients (17%) and in group II in 1 (2.3%). Grade 3 was obtained only in 1 (2%) patient after 30 mCi. Grade 4 was obtained in one patient after 60 mCi (2.3%). The difference in uptake over the neck in the two groups was statistically significant (p < 0.05), although the differences in early effectiveness between the both groups according to the 5-degree scale were on the borderline of significance (p = 0.075). There was a correlation between uptake before and after ablation in 30 mCi group, which was not seen present in 60 mCi group.
Conclusion: For the ablation of thyroid remnants 60 mCi should be considered as a standard dose.