PIK3CA and head and neck squamous cell carcinoma: Activation of the PI3K pathway, generally as a result of PIK3CA amplification, has been reported in upper aerodigestive tract cancers including 12% of lung squamous cell carcinoma (SCC) [23], 18.2% of nasopharyngeal carcinoma [24], 20% of oropharyngeal SCC [25], and 32.2% of HNSCC [16].