Although there are several commercially available serologic biomarkers for colorectal cancer such as carcinoembryonic antigen (CEA), alpha fetoprotein (AFP), and cancer antigen (CA) 19-9 (40–42), it has become clear that these conventional biomarkers have low sensitivity and specificity and are not suited for early diagnosis and predicting prognosis of colorectal cancer (43–45). The gene discussed is CEACAM5; the disease is colorectal cancer.