Of note, central nervous system (CNS) metastasisoccurred in 19% of patients, a high frequency, which mirrors disease progressionoutcomes with HER2-targeted therapies in breast and gastric cancers.110 Therefore, evidence of HER2 amplification in mCRC shouldprompt vigilance in monitoring for CNS metastases, and presence of CNSmetastases in CRC patients should prompt clinicians to consider testing forHER2 amplification regardless of therapy line.111,112. This evidence concerns the gene ERBB2 and gastric cancer.