Initially, HER2 oncogene amplification and/or HER2 receptor overexpression were recognized in up to 30% of breast cancers [67] and in many other tumor types, e.g., gastric, esophageal, lung, bladder, ovarian, endometrial, uterine cervix, head and neck, and colorectal cancers. This evidence concerns the gene ERBB2 and colorectal cancer.