The Prognostic Value of Immunohistochemical Biomarkers in Medullary Thyroid Carcinoma: A Systematic Review and Meta-Analysis

Our systematic review provides a comprehensive synthesis of the literature on immunohistochemical biomarkers in MTC and highlights the need for high-quality validation studies. Our meta-analysis confirms the prognostic value of Ki-67, although with varying certainty due to large differences in study quality. Furthermore, we describe the association of PD-L1 positivity with poorer OS, increased recurrence, and more aggressive clinicopathological features, which supports the rationale for further investigating the potential of anti-PD-1/PD-L1 immunotherapy for advanced MTC.