消化道常用的肿瘤标志物有：癌胚抗原（CEA）、CA199、CA724、CA242、CA50、铁蛋白（SF）。
Ca125, ca19, CEA, AFP, Carcinoembryonic antigen (CEA) is a tumor marker that is measured using a blood test. High levels of CEA may indicate that cancer has spread; however, other medical conditions and some treatments, including certain types of chemotherapy, may raise CEA levels.Cancer antigen 19-9 (CA 19-9) is a tumor marker that is also measured using a blood test. High levels of CA 19-9 may indicate that cancer has spread, but other medical conditions may cause high levels of CA 19-9.DNA ploidy is a test that measures the amount of DNA (genetic material) in cancer cells.The p53 gene is often missing or mutated (changed) in cancer cells.The ras gene (sometimes called KRAS) is often mutated in colorectal cancers.Thymidine synthase (TS), dihydropyrimidine dehydrogenase (DPD), and thymidine phosphorylase (TP) are enzymes (specialized proteins) that may be important for the development of colorectal cancer and may indicate how well the chemotherapy used to treat the cancer is working.Microsatellite instability (MSI) is a measure of the tumor's ability to repair mutations (changes) in the DNA. Cancer cells typically have more mutations than noncancerous cells.18q-loss of heterozygosity/ deleted in colorectal cancer (18q-LOH/DCC) are markers for the loss of or mutation of genes. 18q refers to the place on the chromosome where the genes are lost, and DCC is one of the genes located at 18q that plays a role in the development of colorectal cancer.