The occurrence of breast cancer is often accompanied by gene mutation and/or amplification in tumor cells, such as TP53 (41% of the tumor), PIK3CA (30%), MYC (20%), PTEN (16%), CCND1 (16%), ERBB2 (13%), FGFR1 (11%), and GATA3 (10%) (Nik-Zainal et al., 2016). The gene discussed is ERBB2; the disease is breast cancer.