KRAS and colorectal carcinoma: With regard to systemic chemotherapy, validated biomarkers such as v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS), v-Raf murine sarcoma viral oncogene homolog B1 (BRAF), and microsatellite instability (MSI) cover the extensive heterogeneity of CRC and are suitable for guiding personalized treatment.