PIK3CA and cancer: Finally, genomic identification of significant targets in cancer (GISTIC) analysis36 (Methods) did not detect significant enrichments of PIK3CA amplifications and PIK3R1 deletions in TA-UC (Extended Data Fig. 4a,b) compared to de novo UC (Q < 0.25; Extended Data Fig. 3c), ruling out the possibility that SCNAs account for the lack of PIK3CA and PIK3R1 single-nucleotide variants (SNVs) in TA-UC.