KRAS and colorectal carcinoma: In previous studies, HER2 amplification was highly prevalent in left-sided CRC with reports showing that HER2-positive CRCs are mutually exclusive with KRAS, NRAS, and BRAF mutations [20,29,30]. This is also present in our results, where three patients (n=3/4) with HER2-positive mCRC had the primary tumor on the left side, but with no statistical significance (p=0.49).