Preoperative Endocrine Management of Differentiated Thyroid Cancer

Abstract

This chapter discusses the basic diagnostic procedures that should be performed before a decision is taken to operate on a cancer of the thyroid.

Commentary

• Markus Luster 

1. Department of Nuclear Medicine, University of Ulm, Ulm, Germany

   Markus Luster

The vast majority of non-palpable and even palpable small nodules are histologically benign and the potential for malignancy is low. Although a growing incidence of DTC has been reported worldwide, the detection of a malignant nodule still resembles ‘finding a needle in a haystack’ in many cases. The choice of diagnostic procedures is dependent on local circumstances and iodine supply, and the prevalence of goitre. Technetium-based thyroid scanning plays an important role, especially in areas of iodine deficiency, as autonomously functioning nodules rule out malignancy. Sodium-iodine-symporter expression in DTC is supposed to be 1000-fold lower than in benign thyroid tissue. At least in the hands of our team, only hypofunctioning nodules merit FNA on account of the high rate of false-positive results (‘follicular neoplasia’) in ‘hot nodules’. Borget et al. showed that the cost of FNA depends on cytopathologist performance and unsatisfactory specimen rate. The authors foresee that in the future, routine ultrasound guidance and on-site assessment of cytopathological adequacy would help reduce costs.

The ultimate initial test for thyroid examinations remains neck ultrasound because of its easy accessibility and effectiveness; the main drawback is investigator dependency. The use of high-resolution ultrasonography is generally considered the first choice for the evaluation of thyroid size and morphology. It is much more reliable than palpation of the gland (which has an accuracy of only ~40 %) and reduces the interobserver variation. Sonographic features as predictors of malignancy have been widely reported and debated; the presence of multiple criteria increases specificity at the cost of sensitivity.

The number of incidental findings, i.e. ‘hot spots’ in the thyroid region, has increased with the advent of PET/CT. A systematic use of FDG-PET scanning for screening reasons cannot be recommended because of the lack of specificity, especially in areas with a high prevalence of goitre.