ERBB2 and gastric cancer: HER2 is a well-known therapeutic target in patients with breast and gastric cancer in which overexpression or amplification of HER2 (HER2-positive) is reported in 13-20% and 7-34% of cases, respectively [14]. In CRC, overexpression or amplification of HER2 has been described in 2% to 9.5% of patients; KAS wild-type CRC is more prevalent and occurs more frequently on the left side [10,11,14,15,17-19].