The involvement of micro-ribonucleic acid (microRNAs) in metabolic pathways such as regulation, signal transduction, cell maintenance, and differentiation make them possible biomarkers and therapeutic targets. The purpose of this review is to summarize the information published in the last two and a half years about the involvement of microRNAs in papillary thyroid carcinoma (PTC). Another goal is to understand the perspective offered by the new findings. Main microRNA features such as origin, regulation, targeted genes, and metabolic pathways will be presented in this paper. We interrogated the PubMed database using several keywords: “microRNA” + “thyroid” + “papillary” + “carcinoma”. After applying search filters and inclusion criteria, a selection of 137 articles published between January 2018–June 2020 was made. Data regarding microRNA, metabolic pathways, gene/protein, and study utility were selected and included in the table and later discussed regarding the matter at hand. We found that most microRNAs regularly expressed in the normal thyroid gland are downregulated in PTC, indicating an important tumor-suppressor action by those microRNAs. Moreover, we showed that one gene can be targeted by several microRNAs and have nominally described these interactions. We have revealed which microRNAs can target several genes at once.

Tyrosine kinase inhibitors (TKI) are gaining more ground in oncology, they are widely used in the treatment of multiple types of cancers; still important side effects limit their efficacy. The aim of this study is to evaluate the existing medical literature on TKI induced thyroid dysfunction, to assess the adverse effects of targeted therapy on thyroid function in oncological patients and to evaluate the effects of thyroid dysfunction on disease prognosis. We included in this review 22 original studies published between 2010 and 2019. We used the PubMed database to search for articles upon the development of hypothyroidism and hyperthyroidism in TKI treated patients. After a careful review of the existing literature, we selected the relevant studies and cross-referenced the bibliography of each paper. A number of 1641 patients were included in our review. We found that thyroid dysfunction is not a rare side effect of TKI treatment, approximately 33% of the total number of patients presented clinical hypothyroidism. We also studied the necessity of thyroid hormone substitution treatment, a quarter of evaluated patients needed substitution therapy. Multiple studies showed that there is a link between a patient developing hypothyroidism and progression free survival. Hypothyroidism is a frequent side effect of TKI treatment, which affects the quality of life, sometimes even determines physicians to stop TKI treatment altogether. Our study underlines the necessity of TSH baseline testing and monitoring in patients treated with TKI agents.

Papillary thyroid cancer (PTC) is the most common type of thyroid malignancy and is characterized by slow growth and an indolent biological behavior. Papillary thyroid microcarcinoma is the PTC with the maximum size of the tumor <1cm, considered the most indolent form of thyroid cancer. PTC is usually metastasizes in cervical lymph nodes, lungs and bones and, less commonly, in brain or liver. Skeletal muscle metastases from PTC are extremely rare, a retrospective review of the literature revealed only 13 case reports. Among them, six cases are solitary skeletal muscle metastases, and seven are multiple metastases, most of them being associated with lung lesions. It seems that PTC is prone to metastasizing to the erector spinae and thigh muscles groups with unique cases located in trapezoid, biceps, deltoid, gastrocnemius and rectus abdominis muscles. Although extremely rare, one must bear in mind the fact that muscle metastasis from PTC is possible, and that is the reason we would like to discuss the existing clinical cases and to add a unique case of solitary skeletal muscle metastasis from papillary microcarcinoma.

Thyroid incidentalomas detected by 18 fluoro-2-deoxy-d-glucose (FDG)-positron emission tomography/computed tomography (PET/CT) are a real challenge for nuclear medicine physicians and clinicians. This study aimed to evaluate the risk of malignancy for patients with focal thyroid incidentalomas (TIs) diagnosed through FDG PET/CT. Data from 6900 patients, with a known primary tumor, who had an FDG PET/CT investigation performed were analyzed for the presence of incidental thyroid uptake. The focal TIs were reported, and the patients were referred for further investigation to the endocrinology department. There were 126 patients (1.82%) who presented with focal thyroid uptake, and for 87 of them, investigations were completed with ultrasonography (US), and for 29 with a fine needle aspiration biopsy (FNAB) procedure. Malignancy was detected in 7.93% (10/126) of cases. An arbitrary cutoff value of four was established for the standard uptake value lean body mass (SUVlbm Max) to differentiate the malignant nodules from the benign ones, and this value was significantly associated with malignancy (p = 0.0168). TIs are not so frequent, but they have a potential malignancy risk, and a proper evaluation is required. Even though SUVlbm Max is a predictive factor for malignancy, the FNAB remains the main diagnostic method for the therapeutic management of these patients.

Pediatric thyroid carcinoma is a current area of interest, because there are few studies in this field; the current classification and treatment guidelines are extrapolated from adults, sometimes leading to overly aggressive treatments or incomplete treatment of the disease. The purpose of this retrospective study is to analyze the presentation, diagnosis, treatment, complications, and outcome of children diagnosed with thyroid cancer in the last two decades (2000–2018) at the Oncological Institute “Prof. Dr. Ion Chiricuță” Cluj-Napoca (IOCN) Romania, a tertiary center in a region with environmental influences from both the nuclear fallout of the Chernobyl accident and from iodine deficiency. The results were compared with those obtained in a previous study carried out in the same institution between 1991–2010, and with those obtained in a similar study carried out in Netherlands between 1970–2013, a cohort of children not exposed to the post-Chernobyl fallout. We statistically analyzed 62 patients. Papillary form was present in the majority of cases, and we highlighted the occurrence of thyroid microcarcinoma in children. A total of 85.4% of patients received radioiodine, the total activity being significantly lower compared with the data from literature. In our study, the prognosis of the disease was excellent, with 100% overall survival.

Introduction. The development of thyroid carcinoma is a complex process, in which both genetic and environmental factors play an important role. The rising incidence of thyroid neoplasm determines researchers to investigate factors implicated in this phenomenon. This article aims to elucidate the effects of the Chernobyl nuclear disaster on the Romanian population, studying the existing literature on radiation induced thyroid carcinoma. We analyzed the main studies published on this matter.Methods. We used the PubMed and Google Scholar databases to search for articles upon the effects of the Chernobyl nuclear disaster on the incidence of thyroid carcinoma in the Romanian population. After a careful review of the existing literature, we selected the relevant and accessible studies, the first observation being that data on thyroid related effects of the Chernobyl nuclear disaster are scarce.Results. From the selected studies, results show that there is a possible link between the Chernobyl fallout and the incidence of thyroid carcinoma. Multiple factors have been studied that play an important role in the increasing number of thyroid carcinoma cases, such as: better diagnostic techniques, incidentalomas, microcarcinomas and radiation exposure. In consequence it is difficult to measure the influence that the Chernobyl nuclear fallout has on thyroid carcinoma incidence.Conclusion. Especially in pediatric patients, there seems to be a convincing evidence of radiation related thyroid carcinoma, while in adult patients the rising incidence due exclusively to nuclear fallout is not that clear. Further studies must be done on this matter to clearly see the influence radiation has on the incidence of thyroid cancer.