ERBB3 and colorectal carcinoma: HER2 amplification and protein overexpression can be identified in approximately 6% of CRC patients [13,14,15,16,17]; both HER-2 and HER-3 are overexpressed in liver metastasis in CRC patients (8% and 75%, respectively) [18] HER2 amplification most commonly occurs in the rectum and has been linked to the resistance of EGFR-targeted therapy and lower overall survival compared to HER2 wild-type CRC [19,20].