PIK3CA and neoplasm: By analyzing ctDNA, CTCs or other tumor-derived components in blood or saliva, this approach can reveal a variety of clinically relevant information, including viral etiologies (such as HPV or Epstein–Barr Virus (EBV), tumor-specific genetic alterations (e.g., TP53, PIK3CA, HRAS) and markers of disease burden and/or treatment response.