SIRT1 and metastatic malignant neoplasm in the lymph nodes: Clinically, high SIRT1 corresponds negatively with lymphovascular invasion and both central and lateral lymph node metastasis, and high SIRT3 correlates positively with locoregional recurrence; together, low SIRT1/high SIRT3 stratify patients with more aggressive phenotypes, highlighting both a prognostic dichotomy and direct correlation with metabolic phenotypes in PTC [79].