Colorectal cancer biomarkers as predictors for drug selection
| Biomarker | Mutation frequency | Drug selection | Evidence | Status |
| KRAS codon 12/13 mutations | 40% | Predicts resistance to anti-EGFR therapy | Strong | Validated, in routine clinical use |
| KRAS codon 61/117/146 mutations | 1% | Probably predicts resistance to anti-EGFR therapy | Moderate | In clinical use, not fully validated |
| BRAF V600E mutations | 10% | Probably predicts resistance to anti-EGFR therapy, may predict response to BRAF inhibitors | Moderate | In clinical use, not fully validated |
| PIK3CA mutations | 20% | May predict resistance to anti-EGFR therapy | Limited | No readily available test, not in clinical use |
| PTEN loss | 30% | May predict resistance to anti-EGFR therapy | Limited | No readily available test, not in clinical use |
| Microsatellite instability (MSI) | 15% | May predict adverse outcome with 5-FU and improved outcome with Irinotecan | Moderate | Not yet in routine clinical use as a predictive biomarker |
| 18qLOH/SMAD4 loss | 50% | May predict resistance to 5-FU | Moderate | No readily available test, not in clinical use |
| Topo1 low | 50% | May predict resistance to irinotecan | Limited | No readily available test, not in clinical use |
EGFR, epidermal growth factor receptor; 5-FU, 5-fluorouracill LOH, loss of heterozygosity.