Within the entity of metastatic colorectal cancer (mCRC), there are substantial differences in tumor biology (i.e., RAS-mutant tumors, BRAF-mutant tumors, tumors with microsatellite-instability or Her2/neu expression) that determine treatment choices and outcome (Douillard et al. 2013; Heinemann et al. 2014; Kopetz et al. 2019; Overman et al. 2018; Sartore-Bianchi et al. 2016; Van Cutsem et al. 2016). The gene discussed is BRAF; the disease is metastatic colorectal cancer.