KRAS and breast cancer: Gene-specific markers such as estrogen/progesterone receptors (ER/PR) and human epidermal growth factor receptor 2 (HER2) in breast cancer [31], carcinoembryonic antigen (CEA) in colorectal cancer [32], MYCN in neuroblastoma [33], KRAS in pancreatic ductal carcinoma [34], BRAF in melanoma [35], and EGFR in lung adenocarcimona [36] have found valuable prognostic applications.