Short-term outcome of differentiated thyroid cancer patients receiving a second iodine-131 therapy on the basis of a detectable serum thyroglobulin level after initial treatment

Purpose The aim of this study was to evaluate the usefulness of high-dose 131I therapy administered only on the basis of raised serum Tg levels. Methods Among patients treated with total or near-total thyroidectomy and 131I ablation, 76 (54 women and 22 men) with differentiated thyroid cancer (41 with follicular and 35 with papillary cancer) showed a detectable (i.e. >1.5 ng/ml) serum Tg level on l-thyroxine therapy during follow-up and were included in the study. In these patients, a further 131I therapy was scheduled (range 3.7–9.25 GBq, mean 6.087±1.705). Five to seven days after this radioiodine therapy, patients underwent 131I post-therapy whole-body scan (131I t-WBS). The serum Tg value at 12 months after 131I therapy was evaluated as an indicator of short-term response to radioiodine. Results At evaluation after 12 months, 21 (27.6%) of the 76 patients had a Tg value 1.5 ng/ml, 12 (15.8%) showed a Tg decrease of at least 50%, 22 (29%) had only a minor decrease in Tg (