Table 5.

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

5-FU= 5-Fluorouricil