PIK3CA and head and neck squamous cell carcinoma: The PI3K/AKT/mTOR pathway is the most deregulated cancer-driving signaling pathway in HNC and is active in more than 90% of HNSCC cases.37,38 The PI3KCA gene is mutated in 16–25% of HNC cases, as previously reported.39,40 The mutation frequency of the PI3KCA gene in HPV-positive and HPV-negative HNSCC differs significantly.