Clinical Outcome of Low-risk Differentiated Thyroid Cancer Patients after Radioiodine Remnant Ablation and Recombinant Human Thyroid-stimulating Hormone Preparation

Aim: Recombinant human thyroid-stimulating hormone (rhTSH) has been approved in Europe as a preparation tool for radioiodine ablation of post-surgical thyroid remnants in patients with low-risk differentiated thyroid cancer (DTC). Published studies report that, both thyroid hormone withdrawal and rhTSH preparation result in similar rates of successful remnant ablation, but few studies have determined the effectiveness of rhTSH preparation on disease recurrence. We sought to determine the clinical outcome, considering both ablation success and disease recurrence, of low-risk DTC patients who underwent I-131 ablation. Materials and methods: This retrospective study describes the clinical outcome of 100 patients treated with I-131, remnant ablation after preparation with rhTSH. After ablation, patients were classified as in complete remission, as having no evidence of persistent disease, or as having clinical recurrence on the basis of a subsequent diagnostic whole body scan with I-131, stimulated thyroglobulin and cross-sectional imaging studies. Results: Overall assessment of ablation success was verified and obtained in 75% of patients (75/100). Considering only patients who underwent a diagnostic whole body scan and stimulated thyroglobulin without interfering anti-thyroglobulin antibody, complete ablation was obtained in 96% of patients (75/78). After a follow-up of about 4 years, 78 patients are in complete remission: 75 with initial ablation success and three who achieved a complete remission during subsequent follow-up. Among the remaining 22 patients, 21 have no clinical evidence of disease (NCED), indicating the inability to verify the complete remission or to detect residual disease, as in patients with positive thyroglobulin antibody, whereas one has persistent disease demonstrated only by stimulated thyroglobulin. No recurrences were observed. Of four patients initially classified as having persistent disease, one obtained a complete remission and two are now considered NCED. Conclusion: Our data confirm the favourable outcome, with low rates of recurrence and persistent disease, of patients with low-risk DTC who underwent I-131 ablation after rhTSH. Moreover, our results compare favourably with those reported in the literature in patients prepared with rhTSH, but also in patients prepared with hormone withdrawal. (C) 2011 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.