State of the Art on Thyroid Cancer Biology and Oncology

Thyroid cancer (TC) incidence is rising, necessitating a refined understanding of its complex biology, particularly for advanced forms. This review synthesizes the state-of-the-art knowledge, guided by the WHO 5th Classification (2022), which incorporates molecular findings and introduces categories like Differentiated High-Grade Thyroid Carcinoma (DHGTC) to better stratify prognosis. The review summarizes the molecular changes in thyroid cancer (TC) by establishing a clear link between specific oncogenic alterations and the resulting tumor phenotype, prognosis, risk stratification and therapeutic vulnerabilities. The central importance of the review lies in its comprehensive integration of these molecular changes with the resulting immunological microenvironment and the rationale for novel, personalized therapies. Moreover, high-level genomic instability within aggressive thyroid malignancies promotes an immunosuppressive tumor microenvironment via the selection and recruitment of suppressive immune components, contributing to immune evasion and poor prognosis. This characteristic immunosuppression identifies the aggressive tumors as prime candidates for targeted immunotherapies. The review implicitly argues that understanding the molecular drivers of this immunosuppression is essential for designing effective clinical trials using these novel agents. Diagnostic advancements, including molecular testing for high-risk mutations (<i>BRAF</i>, <i>TERT</i>) and the integration of Artificial Intelligence (AI) for refined risk stratification, are enabling personalized treatment. The evolving molecular and clinical understanding allows for a paradigm shift toward individualized therapies that balance optimal disease control with minimizing morbidity, especially in the context of high-risk disease.