CDKN2A gene encodes p16 and functions as an important tumor suppressor in various human malignancies. Its activation prevents carcinogenesis via induction of cell growth arrest and senescence. Majority of the CDKN2A mutations span exon 2 and result in loss or decreased binding to CDK4/6 leading to uncontrolled cell growth through inactivation of Rb and p53 pathways. Genetic alterations (deletion, mutation, and methylation) in p16 associated with loss of function have been reported in cell lines and primary thyroid tumors. However, predictive or prognostic significance of p16 in thyroid cancer is not clear and correlation with other clinical and lab findings is necessary. Multiple clinical trials are available for patients with CDKN2A deficient tumors.