Why radioiodine remnant ablation is right for most patients with differentiated thyroid carcinoma

Abstract

Recently an editorial by Hay et al. was published in the Journal of Nuclear Medicine favouring abolishing the use of postoperative radioiodine ablation of thyroid remnant tissue (RRA) in what they called ‘stage I’ patients [1]. In our opinion the arguments of our distinguished colleagues throw out the baby with the bathwater. In this article we outline a compelling case for the current practice of applying RRA in most patients when regarding the available evidence from another angle. For many years the recommended therapy for differentiated thyroid carcinoma (DTC), with the exception of microcarcinoma, has consisted of (near-)total thyroidectomy followed by postoperative RRA. Even though results from randomized controlled trials are still missing, this combination has proven its worth as a safe and very effective treatment that results in an improved life expectancy and reduced recurrence rate for patients with DTC in many observational studies. For example, in a survey from North America [2] the majority of physicians are convinced that RRA decreases DTC-related mortality and recurrence, and facilitates DTC follow-up with a low risk of adverse effects. RRA has been adopted as an integral part of several recent international guidelines for the treatment of DTC, such as those of the American Thyroid Association [3], the European Thyroid Association [4], and the European Association of Nuclear Medicine [5], as well as several national guidelines in countries such as the UK, Germany [6, 7], the Netherlands and Austria. In clinical practice, RRA treatment has three goals, as summarized by Schlumberger [8]. First, I therapy may destroy occult microscopic cancer foci, thereby decreasing the long-term risk of recurrent disease [9–12]. Second, it destroys any remaining normal thyroid tissue, thereby increasing the specificity of detectable serum thyroglobulin (Tg) and positive whole-body scintigraphy as markers for persistent or recurrent tumour [8, 10, 13]. Third, the use of a large activity of I for therapy permits postablative scanning, a test for detecting persistent or metastatic carcinoma [14, 15]; upon finding a focus of such persistent or metastatic carcinoma it will also allow precise probeguided removal of such foci in selected cases [16]. Achieving these goals should, through therapy of micrometastases and more sensitive follow-up, lead to a decreased recurrence rate and, more importantly, an improved tumour-specific survival [9]. Over the years several studies have documented the beneficial effects of RRA. Mazzaferri and Jhiang [9] have shown that I is of benefit in all patients except those with stage I disease (defined as unifocal nonmetastasized carcinomas <1.5 cm). RRA leads to a clearly decreased recurrence and mortality rate. In this study no further data were given on the effects of RRA in patients with such Eur J Nucl Med Mol Imaging (2009) 36:343–346 DOI 10.1007/s00259-008-0997-5