Thyroid cancer is the most common endocrine-related malignancy accounting for approximately 1% of all cancer cases. The most frequent thyroid cancer is differentiated thyroid cancer (DTC), a follicular cells-originating tumor, that encompasses up to 95% of all thyroid cancer cases, and in a great majority of cases has a favorable prognosis.1 Thyroid cancer's incidence has continuously increased in the last three decades2,3 and is almost entirely due to the increased incidence of the papillary histotype, with no significant change for the follicular, medullary, or anaplastic histotypes. This is largely attributed to the incidental diagnosis of small, indolent, papillary thyroid cancers due to the wide use of imaging procedures for thyroid-unrelated reasons.4 Accordingly, mortality rates have remained stable at lower rates (0.7 and 0.5 cases per 100,000 person-years for women and men, respectively) with higher rates in anaplastic and poorly differentiated thyroid cancers, respectively.5 (Table 1).

The standard of care for DTC includes risk-oriented surgery, postoperative application of I131, and thyroid hormone therapy. In case of radioiodine-refractory disease, re-operation may be required, external beam radiation therapy, interventional radiological procedures, and multikinase or tyrosine kinase inhibitors for the therapy of distant metastases.6 MTC is a less common thyroid cancer, a neuroendocrine malignancy derived from the parafollicular C-cells, accounting for approximately 2%-5% of all thyroid cancer cases.7 The only curative treatment available for MTC is based on surgery. Patients with advanced, metastatic, disease are currently treated with tyrosine kinase inhibitors (TKI) while conventional chemotherapy is generally ineffective. Loco-regional interventional treatments and external beam radiation therapy can be highly effective in reducing symptoms and preventing complications (ie, bone fractures, compression) in patients with critical lesions.8 It also represents 0.4%-1.3% of all thyroid nodules.9 Anaplastic thyroid carcinoma (ATC), is a rare, highly aggressive malignant tumor accounting for 2%-3% of all thyroid gland neoplasms. Unfortunately, ATC continues to be one of the more deadly diseases worldwide and carries a very poor prognosis.6 Our present review aims to critically discuss the appropriate role of and emerging opportunities for molecular imaging and theranostics in different thyroid cancer histotypes.