Several arguments have called for the assessment of PIK3CA status in the metastatic setting, including arguments regarding (1) a risk of genomic evolution between the initial and metastatic tumor, (2) a risk of poor quality and/or quantity of DNA extracted from archival biopsies of formalin-fixed paraffin-embedded (FFPE) primary cancers stored for a long time. The gene discussed is PIK3CA; the disease is metastatic neoplasm.