ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Endocrine Abstracts (2008) 16 S27.2

Management of differentiated thyroid cancer

Furio Pacini

University of Siena, Siena, Italy.

The initial management of differentiated thyroid cancer is based on total thyroidectomy and radioiodine ablative therapy. Less radical treatment is advocate only in unifocal microcarcinomas. Following initial treatment, long term follow-up is initiated, aimed to the early discovery of persistent or recurrent disease. Follow-up strategies has changed in recent years, after the introduction in the clinical practice of neck ultrasound and recombinant human TSH (rhTSH). The drug has been developed as an alternative to thyroid hormone withdrawal in those circumstances when TSH stimulation is needed. In initial clinical trials the drug has been very effective in patients on l-thyroxine suppressive therapy. Two daily 0.9-mg injections stimulate thyroidal 131I uptake and thyroglobulin (Tg) secretion to a degree equal to 2–3 weeks of hormone withdrawal. Several independent works have confirmed the efficacy of rhTSH-based follow-up in clinical practice. Based on these findings it is proposed that the follow-up of DTC patients may consist of periodical serum Tg measurement (in AbTg negative patients) and 131-I uptake after stimulation with rhTSH, with the aim of selecting patients with persistent disease to be submitted to the more appropriate treatment. In addition, using rhTSH, serum Tg measurement is more sensitive than diagnostic WBS in detecting residual disease and the routine use of diagnostic WBS has been questioned. In particular, the results of rhTSH-stimulated Tg combined with the results of neck ultrasonography has the highest diagnostic accuracy, near to 100%, in detecting patients with residual disease. Altogether the available evidence is sufficient to propose a diagnostic follow-up of DTC patients based mainly on the use of rhTSH-stimulated serum Tg and neck ultrasound. Such an attitude will preserve the patients’ quality of life by avoiding hypothyroidism and will save many unnecessary diagnostic WBS, reducing the need for imaging and 131-I WBS to the minority of patients with strong suspicion of residual disease.

A second important application of rhTSH is the preparation of patients undergoing post-surgical 131-iodine thyroid ablation. Recent prospective trials, have shown that thyroid ablation with 100 mCi or 50 mCi of radioiodine have similar rates of successful ablation in patients prepared with rhTSH and in those in whom thyroid hormone was withdrawn. Dosimetric studies showed that a further advantage of using rhTSH was a one-third reduction in the radiation dose delivered to the blood. Based on these studies, rhTSH has been approved in Europe and USA for post-operative thyroid ablation.

In conclusion, the introduction of rhTSH and neck ultrasonography has greatly facilitated the current protocol for the management of differentiated thyroid cancer patients both in the diagnostic and therapeutic setting.

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