Background: Pathogenic germline mutations affecting the RET proto-oncogene underlie the development of hereditary medullary thyroid carcinoma (MTC). The aims of this study were to evaluate the prevalence of germline RET mutations in a large series of MTC, collected over the last 25 years, and to reappraise their clinical significance. Methods: We performed RET genetic screening in 2031 Italian subjects: patients who presented with sporadic (n = 1264) or hereditary (n = 117) MTC, plus 650 relatives. Results: A RET germline mutation was found in 115/117 (98.3%) hereditary and in 78/1264 (6.2%) apparently sporadic cases: in total, 42 distinct germline variants were found. The V804M mutation was the most prevalent in our cohort, especially in cases that presented as sporadic, while mutations affecting cysteine residues were the most frequent in the group of clinically hereditary cases. All M918T mutations were “de novo” and exclusively associated with MEN2B. Several variants of unknown significance (VUS) were also found. Conclusions: a) RET genetic screening is informative in both hereditary and sporadic MTC; b) the prevalence of different mutations varies with V804M being the most frequent; c) the association genotype–phenotype is confirmed; d) by RET screening, some VUS can be found but their pathogenic role must be demonstrated before screening the family.

Differentiated thyroid cancers (DTC) are commonly and successfully treated with total thyroidectomy plus/minus radioiodine therapy (RAI). Medullary thyroid cancer (MTC) is only treated with surgery but only intrathyroidal tumors are cured. The worst prognosis is for anaplastic (ATC) and poorly differentiated thyroid cancer (PDTC). Whenever a local or metastatic advanced disease is present, other treatments are required, varying from local to systemic therapies. In the last decade, the efficacy of the targeted therapies and, in particular, tyrosine kinase inhibitors (TKIs) has been demonstrated. They can prolong the disease progression-free survival and represent the most important therapeutic option for the treatment of advanced and progressive thyroid cancer. Currently, lenvatinib and sorafenib are the approved drugs for the treatment of RAI-refractory DTC and PDTC while advanced MTC can be treated with either cabozantinib or vandetanib. Dabrafenib plus trametinib is the only approved treatment by FDA for BRAF^V600E mutated ATC. A new generation of TKIs, specifically for single altered oncogenes, is under evaluation in phase 2 and 3 clinical trials. The aim of this review was to provide an overview of the current and future treatments of thyroid cancer with regards to the advanced and progressive cases that require systemic therapies that are becoming more and more targeted on the molecular identity of the tumor.

Thyroglobulin (Tg) is a glycoprotein specifically synthesized by follicular thyroid epithelium. After thyroidectomy and remnant (131)I ablation, serum Tg is a specific and sensitive marker for the presence of thyroid cancer tissue, and its measurement is fundamental in the follow-up of patients affected by differentiated thyroid carcinomas (DTCs), being even more sensitive than diagnostic whole-body scan. Unfortunately, serum Tg measurement becomes useless in approximately 15-25% of DTC cases who are positive for anti-Tg antibodies that interfere with the Tg measurement. In these cases, Tg mRNA measurement has been proposed as an alternative to serum Tg determination. The aim of this study was to verify the sensitivity and specificity of Tg mRNA measurement, performed by quantitative real-time RT-PCR, in a series of 100 subjects (80 DTC patients and 20 controls). From our data, the sensitivity and the specificity of the blood Tg mRNA measurement are 82.3 and 24.2%, respectively, with a positive predictive value and a negative predictive value of 65.6 and 43.7%, respectively. The comparison of the Tg mRNA with the serum Tg, measured by both chemiluminescent and ultrasensitive ELISA methods, confirmed the low specificity of the Tg mRNA assay. The hypothesis that Tg mRNA detectable levels could be predictive of future recurrences is not supported by the long follow-up (median, 7 yr; range, 3-29 yr) of our disease-free patients, who did not develop any recurrences in their clinical history. Moreover, nine disease-free patients, who showed positive levels of Tg mRNA (11.8-336 pg equivalents/ micro g RNA), were confirmed to be serum Tg free, both in basal conditions and after recombinant human TSH stimulation, 4 yr after the Tg mRNA detection. In conclusion, we demonstrated that the Tg mRNA assay is of poor utility in the follow-up of DTC patients. On the contrary, serum Tg measurement is a very sensitive and specific thyroid tumor marker, and we recommend that the follow-up of patients affected by DTC must be performed using serum Tg rather than blood Tg mRNA measurement.

In the last decade, multikinase inhibitors (MKIs) have changed the paradigm of treatment of advanced and progressive thyroid cancer. Compared with the traditional treatment with chemotherapy and radiotherapy, these new drugs have shown a good efficacy in controlling the neoplastic disease, and also a different toxicity profile compared to traditional chemotherapy, milder but still present and involving mainly the nutritional profile. Weight loss, nausea, anorexia, stomatitis, diarrhea may be associated with malnutrition and cancer-related cachexia. The latter is characteristic of the advanced cancer stage and may be present before starting MKIs, or may develop afterwards. Adverse events with nutritional impact may cause a significant impairment of quality of life, often requiring dose reduction and sometimes drug discontinuation, but with a lower efficacy on the neoplastic disease. The aim of this paper was to discuss the role of nutritional therapy in advanced thyroid cancer and the importance of prevention, early recognition and careful management of malnutrition and cachexia during systemic therapy with MKIs.

Background: Serum Ca19.9 positivity is a prognostic factor for mortality in patients with advanced medullary thyroid cancer (aMTC), independently from calcitonin doubling time (DT). However, it is unknown whether aMTC patients who become positive for Ca19.9 also have progressive disease (PD) according to response evaluation criteria in solid tumors (RECIST) and whether Ca19.9 DT has a role in the management of aMTC patients. The aims of this study were to evaluate whether in aMTC, when serum Ca19.9 becomes positive, PD develops, and to determine the role of Ca19.9 DT in predicting mortality and PD. Patients and Methods: Serum Ca19.9 was periodically measured in 107 aMTC patients, and the DTs were calculated. Restaging of the disease was radiologically performed in 104 of 107 patients and PD was evaluated according to RECIST. Results: At the end of follow-up, 25 of 107 patients were Ca19.9 positive and PD was identified in 30 of 104 patients. No significant association was found between Ca19.9 positivity and PD, while there was a significant association between Ca19.9 positivity and mortality ( p < 0.0001). Ca19.9 DTs <6 months and <1 year were not associated with PD but were associated with mortality ( p < 0.0001 and p < 0.0001, respectively). In particular, 3 patients who had a Ca19.9 DT <6 months with no evidence of PD according to RECIST died of their disease after 6, 5, and 3 months, respectively. Conclusions: Serum Ca19.9 positivity and DTs <6 months and <1 year are prognostic factors for mortality but not for PD. Serum Ca19.9 positivity and DTs <6 months and <1 year should be considered in the decision-making process of whether to initiate systemic therapy even if there is no evidence of PD according to RECIST.