The Thyroid Tumor Microenvironment: Potential Targets for Therapeutic Intervention and Prognostication.

Thyroid cancer is the most common endocrine malignancy and incidences are rising rapidly, in both pediatric and adult populations. Many thyroid tumors are successfully treated which results in low mortality rates, but there is often a significant morbidity associated with thyroid cancer treatments. For patients with tumors that are not successfully treated with surgical resection or radioactive iodine treatment, prognosis is dramatically reduced. Patients diagnosed with anaplastic thyroid cancer face a very grim prognosis with a median survival of 6 months post-diagnosis. There is a critical need to identify patients who are at greatest risk of developing persistent disease and progressing to poorly differentiated or anaplastic disease. Furthermore, development of treatments associated with less morbidity would represent a significant improvement for thyroid cancer survivors. It is well established the stromal cells and components of the tumor microenvironment can drive tumor progression and resistance to therapy. Here we review the current state of what is known regarding the thyroid tumor microenvironment and how these factors may contribute to thyroid tumor pathogenesis. Study of the tumor microenvironment within thyroid cancer is a relatively new field, and more studies are needed to dissect the complex and dynamic crosstalk between thyroid tumor cells and its tumor niche.