Background A new harmful respiratory disease, called COVID-19 emerged in China in December 2019 due to the infection of a novel coronavirus, called SARS-Coronavirus 2 (SARS-CoV-2), which belongs to the betacoronavirus genus, including SARS-CoV-1 and MERS-CoV. SARS-CoV-2 shares almost 80% of the genome with SARS-CoV-1 and 50% with MERS-CoV. Moreover, SARS-CoV-2 proteins share a high degree of homology (approximately 95%) with SARS-CoV-1 proteins. Hence, the mechanisms of SARS-Cov-1 and SARS-Cov-2 infection are similar and occur via binding to ACE2 protein, which is widely distributed in the human body, with a predominant expression in endocrine tissues including testis, thyroid, adrenal and pituitary. Purpose On the basis of expression pattern of the ACE2 protein among different tissues, similarity between SARS-Cov-1 and SARS-Cov-2 and the pathophysiology of COVID-19 disease, we aimed at discussing, after almost one-year pandemic, about the relationships between COVID-19 infection and the endocrine system. First, we discussed the potential effect of hormones on the susceptibility to COVID-19 infection; second, we examined the evidences regarding the effect of COVID-19 on the endocrine system. When data were available, a comparative discussion between SARS and COVID-19 effects was also performed. Methods A comprehensive literature search within Pubmed was performed. This review has been conducted according to the PRISMA statements. Results Among 450, 100 articles were selected. Tissue and vascular damages have been shown on thyroid, adrenal, testis and pituitary glands, with multiple alterations of endocrine function. Conclusion Hormones may affect patient susceptibility to COVID-19 infection but evidences regarding therapeutic implication of these findings are still missing. SARS and COVID-19 may affect endocrine glands and their dense vascularization, impairing endocrine system function. A possible damage of endocrine system in COVID-19 patients should be investigated in both COVID-19 acute phase and recovery to identify both early and late endocrine complications that may be important for patient’s prognosis and well-being after COVID-19 infection.

Poorly differentiated thyroid cancer (PDTC) and anaplastic thyroid cancer (ATC) are rare but highly aggressive malignancies with an extremely short survival. Poor prognosis is due to their unlimited growth, invasion, migration and resistance to common anticancer therapies. Advances in understanding the molecular alterations in thyroid carcinomas led to development of new therapeutic strategies such as kinase inhibitors. Although several of these compounds have been approved by FDA and EMA for the treatment of radioactive-iodine refractory differentiated thyroid cancer (DTC) and medullary thyroid cancer (MTC), no significant clinical efficacy with targeted therapies have been observed in those patients.Herein, we review and summarize the preclinical in vitro evidences of mechanisms of resistance to kinase inhibitors currently used in PDTC and ATC patients.