PDCD1 and thyroid gland carcinoma: From immunotherapy, radioimmunotherapy, and thyroid cancer started more than thirty years ago to recent keywords, the molecular imaging, anaplastic thyroid cancer, anaplastic thyroid carcinoma, checkpoint inhibitor, pd-1 (programmeddeath-1), cabozantinib, chemotherapy, immune checkpoint inhibitors, hypothyroidism, medullary-thyroid cancer, we can see the evolution of the research direction (Fig. 6B).