ERBB2 and Alzheimer disease: RAS, BRAF, ERBB2, and microsatellite instability (MSI)/mismatch repair testing for rectal AD are performed widely to guide the use of anti-epidermal growth factor receptor (EGFR) antibodies, BRAF inhibitors, anti–human epidermal growth factor receptor 2 (HER2) antibodies, and immune checkpoint inhibitors, which have shown efficacy in patients with each specific type of tumor.5-8