Of note, the expression level of HER2 in mCRC was particularly high as compared with the other three groups (Fig. 2C), and the difference in the expression level of HER2 between cancer and matched adjacent tissues in mCRC was greater than the difference in primary CRC (Fig. 2D), suggesting that HER2 was a more suitable potential therapeutic target for mCRC. Here, ERBB2 is linked to cancer.