CDKN2A and cholangiocarcinoma: p16 is one of the possible biomarkers for assessing cervical lymph node metastasis in oral squamous cell carcinoma, and an NGS study of 26 patients with cholangitis-associated cholangiocarcinoma (PSC-CCA) or primary biliary cholangitis (PSC) showed the aberrant expression of p16 consistent with heterogeneity in PSC-CCA [24,25].