Although anti-HER2 (human epidermal growth factor receptor 2) therapy is currently approved for breast, gastric, and gastroesophageal cancers overexpressing the HER2 protein or amplified for the HER2 gene, HER2 aberrations (gene amplification, gene mutations, and protein overexpression) are reported in other diverse malignancies. Indeed, about 1-37% of tumors of the following types harbor HER2 aberrations: bladder, cervix, colon, endometrium, germ cell, glioblastoma, head and neck, liver, lung, ovarian, pancreas, and salivary duct.