Table 1.

Biomarkers that are used at present and are promising for the future

Purpose	Present	Future prospective for validation
Diagnostic marker	Fecal occult blood test, colonoscopy	Serum α‐defensins or C3a‐anaphylatoxin urine diacetyl‐spermine
Prognostic marker
Stage II	–	DNA ploidy in the primary tissues
		8p, 18q impalance in the primary tissues
		Microsatellite instability in the primary tissues (for adjuvant therapy)
Stage III	–	K‐ras mutation in primary tissues
Stage IV	–	Serum preoperative CA19‐9
Patient selection for recurrent tumor	–	K‐ras mutation for cetuximab Tx
Follow‐up maker	Serum carcinoembryonic antigen	Novel diagnostic marker as above