The overexpression of EGFR has been observed in both premalignant lesions and malignant tumors of the lung, in 40–80% patients with NSCLS, in 18–25% of all breast cancer carcinoma (specifically HER2 expression), and subsets of ovarian, lung, prostate and gastric cancers [156,157]. The gene discussed is ERBB2; the disease is gastric cancer.