Our aims were to; (1) identify PIK3CA, AKT1, KRAS and BRAF mutations in familial male breast cancer, (2) assess the relationship between such somatic gene mutations and clinicopathological factors, including BRCA1/2 mutation carrier status, and (3) identify and characterise the PIK3CA/mTOR and MAPK pathway and correlate with any clinicopathological factors and survival. The gene discussed is PIK3CA; the disease is breast cancer.