From the comparison, KRAS (CA19-9 ≥ 25 and CEA ≥ 5: 77.3%, the others: 40%; p = 0.001) and PTEN (CA19-9 ≥ 25 and CEA ≥ 5: 13.7%, the others: 0.7%; p = 0.007) showed significantly higher mutation frequencies from the 22 patients with advanced colorectal cancer. The gene discussed is KRAS; the disease is colorectal cancer.