PIK3CA and cervical squamous cell carcinoma: Consistent with their prevalence in cervical squamous cell carcinomas, PIK3CA mutations are observed in 27.8% and 28.1% of cases in HPV+ head and neck cancers and anal carcinomas from the head and neck TCGA study and the anal carcinoma subset of the MSK-IMPACT cohort (Figure 1) [8,20].