Immune Microenvironment of Thyroid Cancer.

Thyroid cancer (TC) is a highly heterogeneous endocrine malignancy with an increased incidence in women than in men. Previous studies regarding the pathogenesis of TC focused on the pathological changes of the tumor cells while ignoring the importance of the mesenchymal cells in tumor microenvironment. However, more recently, the stable environment provided by the interaction of thyroid cancer cells with the peri-tumoral stroma has been widely studied. Studies have shown that components of an individual's immune system are closely related to the occurrence, invasion, and metastasis of TC, which may affect response to treatment and prognosis of the patients. This article presents a comprehensive review of the immune cells, secreted soluble mediators and immune checkpoints in the immune microenvironment, mechanisms that promoting TC cells immune evasion and existing immunotherapy strategies. Besides it provides new strategies for TC prognosis prediction and immunotherapy.