Onderzoek naar effectiviteit van rhTSH bij schildklierkanker

Patiƫnten met gedifferentieerde schildklierkanker (DTC) worden behandeld met een operatie waarbij de schildklier verwijderd wordt. Deze operatie wordt gevolgd door ablatie met radioactief jodium-131 (I131). Ablatie wil zeggen dat de dosis radioactief jodium hoog is, waardoor achtergebleven schildkliercellen vernietigd worden. Optimale opname van radioactief jodium opname wordt bereikt door het niet slikken van schildklierhormoon of door voorbehandeling met recombinant humaan Thyrotropin Stimulerend Hormoon (rhTSH, thyrogen).

Zes gerandomiseerde studies zijn gepubliceerd waarin beide behandelingen met elkaar zijn vergeleken. Een vergelijking is moeilijk omdat een uniforme definitie van ablatiesucces ontbreekt. Met behulp van een strikte definitie, voerden onderzoekers een observationele studie naar de effectiviteit van rhTSH als voorbereiding voor ablatie.

Recombinant TSH stimulated remnant ablation therapy in thyroid cancer: the success rate depends on the definition of ablation success - An observational study
Anouk N. A. van der Horst-Schrivers, Wim J. Sluiter, Anneke C. Muller Kobold, Bruce H. R. Wolffenbuttel, John T. M. Plukker, Peter H. Bisschop, John M. de Klerk, Imad Al Younis, Paul Lips, Jan W. Smit, Adrienne H. Brouwers, Thera P. Links

Introduction

Patients with differentiated thyroid cancer (DTC) are treated with (near)-total thyroidectomy followed by remnant ablation. Optimal radioiodine-131 (131I) uptake is achieved by withholding thyroid hormone (THW), pretreatment with recombinant human Thyrotropin Stimulating Hormone (rhTSH) is an alternative. Six randomized trials have been published comparing THW and rhTSH, however comparison is difficult because an uniform definition of ablation success is lacking. Using a strict definition, we performed an observational study aiming to determine the efficacy of rhTSH as preparation for remnant ablation.

Patients and methods

Adult DTC patients with, tumor stage T1b to T3, Nx, N0 and N1, M0 were included in a prospective multicenter observational study with a fully sequential design, using a stopping rule. All patients received remnant ablation with 131I using rhTSH. Ablation success was defined as no visible uptake in the original thyroid bed on a rhTSH stimulated 150 MBq 131I whole body scan (WBS) 9 months after remnant ablation, or no visible uptake in the original thyroid bed on a post therapeutic WBS when a second high dose was necessary.

Results

After interim analysis of the first 8 patients, the failure rate was estimated to be 69% (90% confidence interval (CI) 20-86%) and the inclusion of new patients had to be stopped. Final analysis resulted in an ablation success in 11 out of 17 patients (65%, 95% CI 38-86%).

Conclusion

According to this study, the efficacy of rhTSH in the preparation of 131I ablation therapy is inferior, when using a strict definition of ablation success. The current lack of agreement as to the definition of successful remnant ablation, makes comparison between different ablation strategies difficult. Our results point to the need for an international consensus on the definition of ablation success, not only in routine patient’s care but also for scientific reasons.

Trial Registration

Dutch Trial Registration NTR2395


Reacties