CDKN2A and head and neck squamous cell carcinoma: The results of CDKN2A, as a protective factor, showed that HNSCC patients with a high CDKN2A expression contained higher infiltration levels of CD8+ T cells (p < 0.05) and Tregs (p < 0.05) while having lower infiltration levels of M2 macrophages (p < 0.05) (Figure 6E).