CEA is a marker of colon cancer, and it is also found to varying degrees in many other tumors, such as cancers of the gastrointestinal tract outside the colon, lung cancer, breast cancer, ovarian cancer and thyroid cancer, among which CEA is often higher than in other epithelial cancers. It is more relevant in monitoring treatment and prognosis, and a high CEA level after surgery indicates the possibility of recurrence. CEA levels are influenced by smoking habits, and the upper limit of the reference range for healthy smokers is 7 to 10 ng/ml. 20-50% of patients with benign disease have moderately elevated CEA. Especially in benign diseases of the intestine, pancreas, liver and lung, but CEA levels remain in the low part of the pathological range, rarely exceeding 10ng/ml. 2. AFP (alpha-fetoprotein) AFP is used to diagnose primary hepatocellular carcinoma and to monitor the effects of treatment. AFP is also used to diagnose germ cell tumors (non-seminomatous tumors of the testis). Elevated serum AFP is seen in about 9% of patients with malignant tumors and liver metastases; these patients rarely have AFP values above 100 ng/ml and rarely above 500 ng/ml, but their CEA levels are substantially elevated; therefore, simultaneous testing of AFP and CEA can be used to differentially diagnose primary hepatocellular carcinoma and liver metastases. and in the lower part of the pathological range (rarely more than 500 ng/ml). These AFP-positive patients are more likely to develop hepatocellular carcinoma. The sensitivity of CA19-9 in the diagnosis of pancreatic cancer is 82%, and there is no correlation between the concentration and tumor volume. Almost all patients with CA19-9 levels above 10,000 U/ml have distant metastases, and CA19-9 has a sensitivity of 50-75% in hepatobiliary tract cancer. CA19-9 is elevated in many adenocarcinomas, such as gastric, colorectal and lung cancers. CA19-9 is also elevated in various benign and infectious diseases of the gastrointestinal tract and hepatobiliary and pancreatic tracts (mostly at 100 U/ml), often in a “transient” manner. If the CA19-9 level continues to rise, it is particularly suggestive of malignant disease of the pancreas. CA72-4 is a useful tumor marker to monitor the progress and treatment effect of gastric cancer, CA72-4 also has special value in mucinous ovarian cancer, CA72-4 is rarely elevated in benign and infectious diseases. 5.Glycan antigen 242 (CA242) In pancreatic cancer or colorectal cancer, serum CA242 expression is elevated. It is somewhat expressed in gastric cancer. In patients with benign gastrointestinal disorders such as pancreatitis, hepatitis and cirrhosis, CA242 levels are limitedly elevated. CA15-3 is highly sensitive to breast cancer and is the best indicator of postoperative recurrence in breast cancer patients. It is also seen within many other adenocarcinomas, lung, ovarian and pancreatic. Moderate elevation is seen in pregnant women in the first trimester of pregnancy. 7.Glycan antigen 125 (CA125) CA125 is present in plasma ovarian cancer cells and tissues of plasma adenocarcinoma, but not in mucinous ovarian cancer. Serum CA125 is also elevated in many patients with adenocarcinoma of the fallopian tube, endometrium and endocervix. CA125 is also seen to be elevated in gastrointestinal tract tumors, bronchial and breast cancers. It is an important tumor marker to monitor the course of plasma ovarian cancer and the effect of treatment. There is a direct relationship between serum CA125 level and tumor volume. The elevation of CA125 is more obvious in patients with metastatic ovarian cancer. After treatment, CA125 level can be significantly decreased. If it cannot be restored to normal range, the possibility of residual tumor should be considered. Elevated CA125 can be seen in benign gynecological tumors and adnexitis, and mildly elevated in pregnant women in the first three months of pregnancy and patients with various autoimmune diseases, hepatitis, chronic pancreatitis and liver cirrhosis. 8.Squamous epithelial cell carcinoma antigen (SCC) is a marker of squamous cell carcinoma, with high specificity and low sensitivity, SCC is often used to monitor the progression of lung, cervical and head and neck epithelial cell carcinoma. Other squamous cell carcinomas such as skin, esophageal, bladder, penile and anal cancers can cause elevated SCCA levels. Since there is a large amount of SCCA in saliva, sweat and respiratory secretions, blood samples should avoid exposure to skin and saliva. 9.Neuron-specific enolase (NSE) NSE has high sensitivity and specificity for small cell lung cancer. The sensitivity of NSE for neuroblastoma is up to 85%. In benign lung diseases, NSE can reach 20 ng/ml, and in malignant tumors it is mostly above 25 ng/ml. NSE is also present in red blood cells, plasma cells and platelets, and if hemolysis occurs or centrifugation time is prolonged, it can lead to an increase in NSE values. Ferritin (Ferr) is an iron-binding protein, the serum level of which is directly related to the total iron storage in the body. Ferritin is present in patients with hepatocellular carcinoma as an acidic tumor differentiated ferritin and therefore elevated in serum. It is released into the blood in pathological states and is elevated in a variety of malignant disorders, including lymphoma, leukemia, colorectal cancer, breast cancer, pancreatic cancer and lung cancer. 11, Cytokeratin 19 fragment (CYFRA21-1) CYFRA21-1 is a useful tumor marker for non-small cell lung cancer, especially lung squamous cell carcinoma. CYFRA21-1 can be used for the monitoring of muscle invasion in bladder cancer. 12. Human chorionic gonadotropin (HCG) HCG positive and AFP negative in 14% of cases of seminoma alone. HCG levels are elevated in 70%-75% of non-seminomatous tumors in testicular cancer. Choriocarcinoma is usually HCG positive with concomitant AFP negativity. Endodermal sinus tumors are usually concurrently HCG negative and AFP positive. In addition some patients with gallbladder cancer, gynecologic tumors (ovarian, cervical, endometrial and vulvar tumors) have elevated HGC levels. It can be used for diagnosis and monitoring of pregnancy. PSA can be used to monitor the progression of prostate cancer and its outcome and to monitor patients with prostate hypertrophy to detect prostate cancer as early as possible. 90% of patients’ postoperative serum PSA values can be reduced to undetectable trace levels. In patients with prostate hypertrophy, as well as in patients with prostate hypertrophy, the serum PSA level is higher. In patients with prostate hypertrophy and in cases of inflammation of the prostate, serum PSA levels are sometimes significantly elevated. PSA can be suppressed by anti-androgen therapy. 14.Tissue peptide specific antigen (TPSA) Serum TPSA levels are strongly correlated with tumor progression in 80-100% of patients with tumors (e.g., breast, bronchial, cervical, or bladder cancers, etc.). It also showed good sensitivity in bladder cancer, especially the muscle-invasive type. 15.Pepsinogen I and II (PGI and PGII) Pepsinogen (PG) is the precursor of pepsin, reflecting the number of principal cells, and is divided into two types: PGI and PGII. When the gastric mucosa is diseased, PG-secreting cells are involved and the amount of PG in the serum is changed. PGI increases when gastric acid secretion increases and decreases when gastric acid secretion decreases or gastric mucosal glands atrophy, so PGI is known as a pointer to detect the function of gastric acid-secreting cells. PGII correlates more with gastric fundic mucosal lesions, and its elevation is associated with fundic glandular duct atrophy, glandular epithelial hyperplasia or pseudopyloric glandular hyperplasia, and heterotypic hyperplasia. When intestinal epithelial hyperplasia, atypical hyperplasia and gastric cancer are present, PGI secretion will be reduced, and PGI/PGII ratio will also be decreased. Serum PGI and II levels are an effective marker for early diagnosis of gastric cancer. 16.Epididymal protein 4 (HE4) is used for early diagnosis of ovarian cancer. 76.4% sensitivity and 95% specificity of the combined test of HE4 and CA125 are higher than either marker alone. 17.Progranulin-releasing peptide precursor (ProGRP) is the latest tumor marker for the diagnosis of small cell lung cancer (SCLC).