The most frequently mutated and/or amplified genes reported in the tumor cells for early breast cancer detection are TP53 (41% of tumors), PIK3CA (Phosphatidylinositol-4,5-Bisphosphate 3-Kinase Catalytic Subunit Alpha) (30%), MYC (20%), PTEN (Phosphatase and Tensin Homolog deleted on Chromosome 10) (16%), CCND1 (Cyclin D1) (16%), ERBB2 (Erb-B2 Receptor Tyrosine Kinase 2) (13%), FGFR1 (Fibroblast growth factor receptor 1) (11%), and GATA3 (10%). The gene discussed is PIK3CA; the disease is breast cancer.