Revisiting Immune-Based Therapies for Aggressive Follicular Cell–Derived Thyroid Cancers

Background: With our growing understanding of the immune system and mechanisms employed by tumors to evade destruction, the field of cancer immunotherapy has been revitalized. Concurrent inflammation has long been associated with follicular cell–derived thyroid cancer (FDTC). In the last decade, much research has focused on characterizing the tumor-associated immune response in patients with FDTC. Summary: Mast cells, natural killer cells, macrophages, dendritic cells, B cells, and T cells have been identified within FDTC-associated immune infiltrate. Collectively, these findings suggest that the immune response to FDTC is compromised and may even promote tumor progression. A more thorough characterization of the tumor-associated immune response in FDTC may lead to the development of immune-based adjuvant therapies for patients with aggressive disease. Conclusions: Immune-based therapies could provide essential alternatives to patients that cannot be treated surgically, those with recurrent or persistent lymph node metastases, and those with anaplastic thyroid cancer.