Effect of therapeutic radioiodine activity on ablation response in differentiated thyroid cancer patients with cut-off serum thyroglobulin levels after 2 weeks of thyroid hormone withdrawal: a retrospective study

This retrospective study aimed to investigate whether there was a difference in the success rate of removal residual thyroid tissue patients with same cutoff serum thyroglobulin (Tg) value―measured 2 weeks after hormone withdrawal (THW)―for different radioactive iodine (RAI) activities. We identified 132 papillary cancer who were treated total thyroidectomy and RAI therapy evaluate efficacy three radioactivities I-131: 1,110, 3,700, 5,550 MBq. Serum Tg testing performed 1 week before treatment THW (pre-Tg); pre-Tg level below 10 ng/mL. Stimulated levels measured on day I-131 administration (off-Tg). After 6 months treatment, we compared groups for complete ablation, defined as no uptake diagnostic scan, stimulated <1.0 ng/mL, antibody <100 Ninety-five (72.0%) achieved 57.1% (8/14), 78.2% (68/87), 61.3% (19/31) 1,110 MBq, 3,700 MBq groups, respectively. There significant ablation rates between groups. In multivariate analysis, off-Tg predictor ablation. low radioactivity (1,110 MBq) seemed sufficient The is promising useful initial therapy.