EGFR and breast cancer: Overexpression of EGFR was shown to be involved in the development of a majority of epithelial malignancies, including breast cancer, head-and-neck cancer, NSCLC, renal cancer, ovarian cancer and colon cancer [131], because of the sustained production of EGFR ligands in the TME or as a result of mutations in EGFR itself [70,72].