PIK3CA mutations have been reported in 18%–40% (Barbareschi et al., 2007) of BrCa cases; three ‘hotspot’ mutations (E542K, E545K, and H1047R) comprise more than 80% (Campbell et al., 2004) of all PIK3CA mutations and are localized in exons 9 and 20. The gene discussed is PIK3CA; the disease is invasive breast carcinoma.